Modularity, Domain-specificity, and the Organization of Knowledge

Readings

The readings listed below are the foundation of this course. Where available, journal article abstracts from PubMed (an online database providing access to citations from biomedical literature) are included. All students are responsible for the required readings under each topic. In addition, specific students are assigned to read all of the readings under one of the subtopics and present those readings to the class. This list has been compiled by the Department of Brain and Cognitive Sciences, not the course instructor.

MODULARITY

General readings:

Fodor. The Mind Doesn’t Work That Way. MIT Press, 2000, Chap. 43.

-—–. The Modularity of Mind. MIT Press, 1983.

and one of the following sets of readings:

1. A Computational Prospective

Jacobs, R. A. “Computational Studies of the Development of Functionally Specialized Neural Modules.” Trends Cogn Sci 3 (1999): 31-38.

_PubMed abstract: _ Three hypotheses about the activity-dependent development of functionally specialized neural modules are discussed in this review. These hypotheses state that: (1) a combination of structure function correspondences plus the use of competition between neural modules leads to functional specializations; (2) parcellation is due to a combination of neural selectionism, the idea that learning results from a stabilization of some neural connections and the elimination of others, and a locality constraint, which states that connections between nearby neurons are more easily stabilized than those between distant neurons; and (3) a temporal and spatial modulation of plasticity can induce higher functional development in later-developing parts of the nervous system relative to earlier-developing parts. All three hypotheses have been implemented and evaluated in computational models. Limitations of current neuroscientific methodologies mean that computer simulation provides one of the only tools available for evaluating and refining our large-scale theories of the development of functionally specialized neural modules.

Gharamani, Z., and D. M. Wolpert. “Modular Decomposition in Visuomotor Learning.” Nature 386: 392-395.

_PubMed abstract: _ The principle of ‘divide-and-conquer’ the decomposition of a complex task into simpler subtasks each learned by a separate module, has been proposed as a computational strategy during learning. We explore the possibility that the human motor system uses such a modular decomposition strategy to learn the visuomotor map, the relationship between visual inputs and motor outputs. Using a virtual reality system, subjects were exposed to opposite prism-like visuomotor remappings-discrepancies between actual and visually perceived hand locations- for movements starting from two distinct locations. Despite this conflicting pairing between visual and motor space, subjects learned the two starting-point-dependent visuomotor mappings and the generalization of this learning to intermediate starting locations demonstrated an interpolation of the two learned maps. This interpolation was a weighted average of the two learned visuomotor mappings, with the weighting sigmoidally dependent on starting location, a prediction made by a computational model of modular learning known as the “mixture of experts”. These results provide evidence that the brain may employ a modular decomposition strategy during learning.

2. An Evolutionary Perspective

Gallistel, C. R. “The Replacement of General-purpose Learning Models with Adaptively Specialized Learning Models.” In The New Cognitive Neurosciences. Edited by M. Gazzaniga. MIT Press, 2000.

Duchaine B., L. Cosmides, and J. Tooby. “Evolutionary Psychology and the Brain.” Curr Opin Neurobiol 11, 2 (2001): 225-30. Review.

_PubMed abstract: _ The human brain is a set of computational machines, each of which was designed by natural selection to solve adaptive problems faced by our hunter-gatherer ancestors. These machines are adaptive specializations: systems equipped with design features that are organized such that they solve an ancestral problem reliably, economically and efficiently. The search for functionally specialized computational adaptations has now begun in earnest. A host of specialized systems have recently been found, including ones designed for sexual motivation, social inference, judgment under uncertainty and conditioning, as well as content-rich systems for visual recognition and knowledge acquisition.

3. Challenges from Psycholinguistics

MacDonald, M. C., N. H. Pearlmutter, and M. S. Seidenberg. “The Lexical Nature of Syntactic Ambiguity Resolution.” Psychological Review 101 (1994): 676-703.

_PubMed abstract: _ Ambiguity resolution is a central problem in language comprehension. Lexical and syntactic ambiguities are standardly assumed to involve different types of knowledge representations and be resolved by different mechanisms. An alternative account is provided in which both types of ambiguity derive from aspects of lexical representation and are resolved by the same processing mechanisms. Reinterpreting syntactic ambiguity resolution as a form of lexical ambiguity resolution obviates the need for special parsing principles to account for syntactic interpretation preferences, reconciles a number of apparently conflicting results concerning the roles of lexical and contextual information in sentence processing, explains differences among ambiguities in terms of ease of resolution, and provides a more unified account of language comprehension than was previously available.

Tanenhaus, M. K., M. J. Spivey-Knowlton, K. M. Eberhard, and J. C. Sedivy. “Integration of Visual and Linguistic Information in Spoken Language Comprehension.” Science 268 (1995): 1632-1634.

_PubMed abstract: _ Psycholinguists have commonly assumed that as a spoken linguistic message unfolds over time, it is initially structured by a syntactic processing module that is encapsulated from information provided by other perceptual and cognitive systems. To test the effects of relevant visual context on the rapid mental processes that accompany spoken language comprehension, eye movements were recorded with a head-mounted eye-tracking system while subjects followed instructions to manipulate real objects. Visual context influenced spoken word recognition and mediated syntactic processing, even during the earliest moments of language processing.

Trueswell, J. C., I. Sekerina, N. M. Hill, and M. L. Logrip. “The Kindergarten-path Effect: Studying On-line Sentence Processing in Young Children.” Cognition 73 (1999): 89-134.

_PubMed abstract: _ A great deal of psycholinguistic research has focused on the question of how adults interpret language in real time. This work has revealed a complex and interactive language processing system capable of rapidly coordinating linguistic properties of the message with information from the context or situation (e.g. Altmann & Steedman, 1988; Britt, 1994; Tanenhaus, Spivey-Knowlton, Eberhard & Sedivy, 1995; Trueswell & Tanenhaus, 1991). In the study of language acquisition, however, surprisingly little is known about how children process language in real time and whether they coordinate multiple sources of information during interpretation. The lack of child research is due in part to the fact that most existing techniques for studying language processing have relied upon the skill of reading, an ability that young children do not have or are only beginning to acquire. We present here results from a new method for studying children’s moment-by-moment language processing abilities, in which a head-mounted eye-tracking system was used to monitor eye movements as participants responded to spoken instructions. The results revealed systematic differences in how children and adults process spoken language: Five Year Olds did not take into account relevant discourse/pragmatic principles when resolving temporary syntactic ambiguities, and showed little or no ability to revise initial parsing commitments. Adults showed sensitivity to these discourse constraints at the earliest possible stages of processing, and were capable of revising incorrect parsing commitments. Implications for current models of sentence processing are discussed.

4. Challenges from the Associationists

McClelland, J. L. “Integration of Information: Reflections on the Theme of Attention and Performance XVI.” In Attention and Performance XVI. Edited by T. Inui and J. L. McClelland. Cambridge, MA: MIT Press, 1996.

Plaut, D. “Double Dissociations Without Modularity: Evidence from Connectionist Psychology.” J. Clinical & Exper. Neuropsychology 17 (1995): 291-321.

_PubMed abstract: _ Many theorists assume that the cognitive system is composed of a collection of encapsulated processing components or modules, each dedicated to performing a particular cognitive function. On this view, selective impairments of cognitive tasks following brain damage, as evidenced by double dissociations, are naturally interpreted in terms of the loss of particular processing components. By contrast, the current investigation examines in detail a double dissociation between concrete and abstract work reading after damage to a connectionist network that pronounces words via meaning and yet has no separable components (Plaut & Shallice, 1993). The functional specialization in the network that gives rise to the double dissociation is not transparently related to the network’s structure, as modular theories assume. Furthermore, a consideration of the distribution of effects across quantitatively equivalent individual lesions in the network raises specific concerns about the interpretation of single-case studies. The findings underscore the necessity of relating neuropsychological data to cognitive theories in the context of specific computational assumptions about how the cognitive system operates normally and after damage.

5. Additive Factors Approaches to Functional Dissociations

Pinel, P., D. Riviere, D. Le Bihan, and S. Dehaene. “Modulation of Parietal Activation by Semantic Distance in a Number Comparison Task.” Neuroimage. 2001 Nov; 14 (5): 1013-26.

_PubMed abstract: _ The time to compare two numbers shows additive effects of number notation and of semantic distance, suggesting that the comparison task can be decomposed into distinct stages of identification and semantic processing. Using event-related fMRI and high-density ERPs, we isolated cerebral areas where activation was influenced by input notation (verbal or Arabic notation). The bilateral extrastriate cortices and a left precentral region were more activated during verbal than during Arabic stimulation, while the right fusiform gyrus and a set of bilateral inferoparietal and frontal regions were more activated during Arabic than during verbal stimulation. We also identified areas that were influenced solely by the semantic content of the stimuli (numerical distance between numbers to be compared) independent of the input notation. Activation tightly correlated with numerical distance was observed mainly in a group of parietal areas distributed bilaterally along the intraparietal sulci and in the precuneus, as well as in the left middle temporal gyrus and posterior cingulate. Our results support the assumption of a central semantic representation of numerical quantity that relies on a common parietal network shared among notations.

Sternberg, S. “Separate Modifiability, Mental Modules, and the Use of Pure and Composite Measures to Reveal Them.” Acta Psychol 106 (2001): 147-246.

_PubMed abstract: _ How can we divide a complex mental process into meaningful parts? In this paper, I explore an approach in which processes are divided into parts that are modular in the sense of being separately modifiable. Evidence for separate modifiability is provided by an instance of selective influence: two factors F and G (usually experimental manipulations) such that part A is influenced by F but invariant with respect to G, while part B is influenced by G but invariant with respect to F. Such evidence also indicates that the modules are functionally distinct. If we have pure measures MA and MB, each of which reflects only one of the parts, we need to show that MA is influenced by F but not G, while MB is influenced by G but not F. If we have only a composite measure MAB of the entire process, we usually also need to confirm a combination rule for how the parts contribute to MAB. I present a taxonomy of separate-modifiability methods, discuss their inferential logic, and describe several examples in each category. The three categories involve measures that are derived pure (based on different transformations of the same data; example: separation of sensory and decision processes by signal detection theory), direct pure (based on different data; example: selective effects of adaptation on spatial-frequency thresholds), and composite (examples: the multiplicative-factor method for the analysis of response rate; the additive-factor method for the analysis of reaction time). Six of the examples concern behavioral measures and functional processes, while four concern brain measures and neural processes. They have been chosen for their interest and importance; their diversity of measures, species, and combination rules; their illustration of different ways of thinking about data; the questions they suggest about possibilities and limitations of the separate-modifiability approach; and the case they make for the fruitfulness of searching for mental modules

INNATENESS AND PLASTICITY IN VISION

General readings:

Crair, M. “Neuronal Activity During Development: Permissive or Instructive?” Current Opinion in Neurobiology 9, 1 (1999): 88-93.

_PubMed abstract: _ Experimental studies over the past year have shown that neural activity has a range of effects on the development of neural pathways. Although activity appears unimportant for establishing many aspects of the gross morphology and topology of the brain, there are many cases where the presence of neural activity is essential for the formation of a mature system of neural connections; in some instances, the pattern of neural activity actually orchestrates the final arrangement of neural connections.

Sur, M., and C. A. Leamey. “Development and Plasticity of Cortical Areas and Networks.” Nat. Rev. Neuroscience 4 (2001): 251-262.

_PubMed abstract: _ The development of cortical layers, areas and networks is mediated by a combination of factors that are present in the cortex and are influenced by thalamic input. Electrical activity of thalamocortical afferents has a progressive role in shaping cortex. For early thalamic innervation and patterning, the presence of activity might be sufficient; for features that develop later, such as intracortical networks that mediate emergent responses of cortex, the spatiotemporal pattern of activity often has an instructive role. Experiments that route projections from the retina to the auditory pathway alter the pattern of activity in auditory thalamocortical afferents at a very early stage and reveal the progressive influence of activity on cortical development. Thus, cortical features such as layers and thalamocortical innervation are unaffected, whereas features that develop later, such as intracortical connections, are affected significantly. Surprisingly, the behavioural role of ‘rewired’ cortex is also influenced profoundly, indicating the importance of patterned activity for this key aspect of cortical function.

Maurer, D., and T. Lewis. Visual Acuity: The Role of Visual Input in Inducing Postnatal Change. (In press).

and one of the following sets of readings:

1. Arealization and its Development

Felleman, D. J., and D. C. Van Essen. “Distributed Hierarchical Processing in the Primate Cerebral Cortex.” Cereb Cortex 1 (1991): 1-47. Review.

_PubMed abstract: _ In recent years, many new cortical areas have been identified in the macaque monkey. The number of identified connections between areas has increased even more dramatically. We report here on (1) a summary of the layout of cortical areas associated with vision and with other modalities, (2) a computerized database for storing and representing large amounts of information on connectivity patterns, and (3) the application of these data to the analysis of hierarchical organization of the cerebral cortex. Our analysis concentrates on the visual system, which includes 25 neocortical areas that are predominantly or exclusively visual in function, plus an additional 7 areas that we regard as visual-association areas on the basis of their extensive visual inputs. A total of 305 connections among these 32 visual and visual-association areas have been reported. This represents 31% of the possible number of pathways if each area were connected with all others. The actual degree of connectivity is likely to be closer to 40%. The great majority of pathways involve reciprocal connections between areas. There are also extensive connections with cortical areas outside the visual system proper, including the somatosensory cortex, as well as neocortical, transitional, and archicortical regions in the temporal and frontal lobes. In the somatosensory/motor system, there are 62 identified pathways linking 13 cortical areas, suggesting an overall connectivity of about 40%. Based on the laminar patterns of connections between areas, we propose a hierarchy of visual areas and of somatosensory/motor areas that is more comprehensive than those suggested in other recent studies. The current version of the visual hierarchy includes 10 levels of cortical processing. Altogether, it contains 14 levels if one includes the retina and lateral geniculate nucleus at the bottom as well as the entorhinal cortex and hippocampus at the top. Within this hierarchy, there are multiple, intertwined processing streams, which, at a low level, are related to the compartmental organization of areas V1 and V2 and, at a high level, are related to the distinction between processing centers in the temporal and parietal lobes. However, there are some pathways and relationships (about 10% of the total) whose descriptions do not fit cleanly into this hierarchical scheme for one reason or another. In most instances, though, it is unclear whether these represent genuine exceptions to a strict hierarchy rather than inaccuracies or uncertainities in the reported assignment.

Schiller, Peter. “On the Specificity of Neurons and Visual Areas.” Behav Brain Res 76 (1996): 21-35.

_PubMed abstract: _ The dominant view during the past 40 years has been that the visual system analyzes the visual scene by breaking it down into basic attributes such as color, form, motion, depth and texture. Individual dedicated neurons and specific visual areas were believed to be devoted to the analysis of each of these attributes. Current research has challenged these views by emphasizing that neurons, especially in the cortex, have multifunctional properties and therefore serve as general-purpose analyzers rather than feature detectors. Consequently, it appears that most extrastriate visual areas, rather than each being devoted to the analysis of a specific basic visual attribute, perform several different tasks and thereby engage in more advanced and complex analyses than had been realized.

2. Development of Ocular Dominance

Crair, M. C., D. C. Gillespie, and M. P. Stryker. “The Role of Visual Experience in the Development of Columns in Cat Visual Cortex.” Science 179 (1998): 566-570.

_PubMed abstract: _ The role of experience in the development of the cerebral cortex has long been controversial. Patterned visual experience in the cat begins when the eyes open about a week after birth. Cortical maps for orientation and ocular dominance in the primary visual cortex of cats were found to be present by 2 weeks. Early pattern vision appeared unimportant because these cortical maps developed identically until nearly 3 weeks of age, whether or not the eyes were open. The naive maps were powerfully dominated by the contralateral eye, and experience was needed for responses to the other eye to become strong, a process unlikely to be strictly Hebbian. With continued visual deprivation, responses to both eyes deteriorated, with a time course parallel to the well-known critical period of cortical plasticity. The basic structure of cortical maps is therefore innate, but experience is essential for specific features of these maps, as well as for maintaining the responsiveness and selectivity of cortical neurons.

Crowley, and Katz. “Early Development of Ocular Dominance Columns.” Science 190 (2000): 1271-1273.

_PubMed abstract: _ The segregation of lateral geniculate nucleus (LGN) axons into ocular dominance columns is believed to involve a prolonged, activity-dependent sorting process. However, visualization of early postnatal ferret LGN axons by direct LGN tracer injections revealed segregated ocular dominance columns <7 days after innervation of layer 4. These early columns were unaffected by experimentally induced imbalances in retinal activity, implying that different mechanisms govern initial column formation and their modification during the subsequent critical period. Instead of activity-dependent plasticity, we propose that ocular dominance column formation relies on the targeting of distinct axonal populations to defined locales in cortical layer 4.

3. Rewiring Sensory Cortex

Krubitzer, L., and K. J. Huffman. “Arealization of the Neocortex in Mammals: Genetic and Epigenetic Contributions to the Phenotype.” Brain Behav Evol 55, 6 (Jun. 2000): 322-35.

_PubMed abstract: _ The neocortex is composed of areas that are functionally, anatomically and histochemically distinct. In comparison to most other mammals, humans have an expanded neocortex, with a pronounced increase in the number of cortical areas. This expansion underlies many complex behaviors associated with human capabilities including perception, cognition, language and volitional motor responses. In the following review we consider data from comparative studies as well as from developmental studies to gain insight into the mechanisms involved in arealization, and discuss how these mechanisms may have been modified in different lineages over time to produce the remarkable degree of organizational variability observed in the neocortex of mammals. Because any phenotype is a result of the complex interactions between genotypic influences and environmental factors, we also consider environmental, or epigenetic, contributions to the organization of the neocortex.

Sur, M., A. Angelucci, and J. Sharma. “Rewiring Cortex: The Role of Patterned Activity in Development and Plasticity of Neocortical Circuits.” J. Neurobiology 41 (1999): 33-43.

_PubMed abstract: _ Visually driven activity is not required for the establishment of ocular dominance columns, orientation columns, and long-range horizontal connections in visual cortex, although spontaneous activity appears to be necessary. The role of activity may be instructive or simply permissive; evidence for an instructive role requires inquiry into the role of the pattern of activity in shaping cortical circuits. The few experiments that have probed the role of patterned activity include the effects of artificial strabismus, artificial stimulation of the optic nerve, and rewiring visual projections from the retina to the auditory thalamus and cortex. These experiments demonstrate that patterned activity is vital for the maintenance of thalamocortical, local intracortical, and long-range horizontal connections in cortex.

4. Rewiring in Humans

Cohen, L. G., P. Celnik, A. Pascual-Leone, B. Corwell, L. Falz, J. Dambrosia, M. Honda, N. Sadato, C. Gerloff, M. D. Catala, and M. Hallett. “Functional Relevance of Cross-modal Plasticity in Blind Humans.” Nature 389 (1997): 180-183.

_PubMed abstract: _ Functional imaging studies of people who were blind from an early age have revealed that their primary visual cortex can be activated by Braille reading and other tactile discrimination tasks. Other studies have also shown that visual cortical areas can be activated by somatosensory input in blind subjects but not those with sight. The significance of this cross-modal plasticity is unclear, however, as it is not known whether the visual cortex can process somatosensory information in a functionally relevant way. To address this issue, we used transcranial magnetic stimulation to disrupt the function of different cortical areas in people who were blind from an early age as they identified Braille or embossed Roman letters. Transient stimulation of the occipital (visual) cortex induced errors in both tasks and distorted the tactile perceptions of blind subjects. In contrast, occipital stimulation had no effect on tactile performance in normal-sighted subjects, whereas similar stimulation is known to disrupt their visual performance. We conclude that blindness from an early age can cause the visual cortex to be recruited to a role in somatosensory processing. We propose that this cross-modal plasticity may account in part for the superior tactile perceptual abilities of blind subjects.

Roeder, B. A., W. Teder-Salejarvi, A. Sterr, R. Roesler, S. A. Hillyard, and H. J. Neville. “Improved Auditory Spatial Tuning in Blind Humans.” Nature 400 (1999): 162-166.

_PubMed abstract: _ Despite reports of improved auditory discrimination capabilities in blind humans and visually deprived animals, there is no general agreement as to the nature or pervasiveness of such compensatory sensory enhancements. Neuroimaging studies have pointed out differences in cerebral organization between blind and sighted humans, but the relationship between these altered cortical activation patterns and auditory sensory acuity remains unclear. Here we compare behavioural and electrophysiological indices of spatial tuning within central and peripheral auditory space in congenitally blind and normally sighted but blindfolded adults to test the hypothesis (raised by earlier studies of the effects of auditory deprivation on visual processing) that the effects of visual deprivation might be more pronounced for processing peripheral sounds. We find that blind participants displayed localization abilities that were superior to those of sighted controls, but only when attending to sounds in peripheral auditory space. Electrophysiological recordings obtained at the same time revealed sharper tuning of early spatial attention mechanisms in the blind subjects. Differences in the scalp distribution of brain electrical activity between the two groups suggest a compensatory reorganization of brain areas in the blind that may contribute to the improved spatial resolution for peripheral sound sources.

Sadato, N., A. Pascual-Leone, J. Grafman, V. Ibaniez, M. P. Deiber, G. Dold, and M. Hallett. “Activation of the Primary Visual Cortex by Braille Reading in Blind Subjects.” Nature 380 (1996): 526-528.

_PubMed abstract: _ Primary visual cortex receives visual input from the eyes through the lateral geniculate nuclei, but is not known to receive input from other sensory modalities. Its level of activity, both at rest and during auditory or tactile tasks, is higher in blind subjects than in normal controls, suggesting that it can subserve nonvisual functions; however, a direct effect of non-visual tasks on activation has not been demonstrated. To determine whether the visual cortex receives input from the somatosensory system we used positron emission tomography (PET) to measure activation during tactile discrimination tasks in normal subjects and in Braille readers blinded in early life. Blind subjects showed activation of primary and secondary visual cortical areas during tactile tasks, whereas normal controls showed deactivation. A simple tactile stimulus that did not require discrimination produced no activation of visual areas in either group. Thus in blind subjects, cortical areas normally reserved for vision may be activated by other sensory modalities.

Sterr, A., M. M. Muller, T. Elbert, B. Rockstroh, C. Pantev, and E. Taub. “Changed Perceptions in Braille Readers.” Nature 391 (1998): 134-135.

OBJECTS

General readings:

Kahneman, D., A. Treisman, and B. J. Gibbs. “The Reviewing of Object Files: Object-specific Integration of Information.” Cognitive Psychology 24 (1992): 175-219.

_PubMed abstract: _ A series of experiments explored a form of object-specific priming. In all experiments a preview field containing two or more letters is followed by a target letter that is to be named. The displays are designed to produce a perceptual interpretation of the target as a new state of an object that previously contained one of the primes. The link is produced in different experiments by a shared location, by a shared relative position in a moving pattern, or by successive appearance in the same moving frame. An object-specific advantage is consistently observed: naming is facilitated by a preview of the target, if (and in some cases only if) the two appearances are linked to the same object. The amount and the object specificity of the preview benefit are not affected by extending the preview duration to 1 s, or by extending the temporal gap between fields to 590 ms. The results are interpreted in terms of a reviewing process, which is triggered by the appearance of the target and retrieves just one of the previewed items. In the absence of an object link, the reviewing item is selected at random. We develop the concept of an object file as a temporary episodic representation, within which successive states of an object are linked and integrated.

Scholl, B. J. “Objects and Attention: The State of the Art.” Cognition 80 (2001): 1-46.

_PubMed abstract: _ What are the units of attention? In addition to standard models holding that attention can select spatial regions and visual features, recent work suggests that in some cases attention can directly select discrete objects. This paper reviews the state of the art with regard to such ‘object-based’ attention, and explores how objects of attention relate to locations, reference frames, perceptual groups, surfaces, parts, and features. Also discussed are the dynamic aspects of objecthood, including the question of how attended objects are individuated in time, and the possibility of attending to simple dynamic motions and events. The final sections of this review generalize these issues beyond vision science, to other modalities and fields such as auditory objects of attention and the infant’s ‘object concept’.

Spelke, E. S., P. Vishton, and C. Von Hofsten. “Object Perception, Object-directed Action, and Physical Knowledge in Infancy.” In The Cognitive Neurosciences. Edited by M. Gazzaniga. Cambridge, MA: MIT Press, 1995, pp. 165-179.

and one of the following sets of readings:

1. Attentive Tracking in Adults

Culham, J., P. Cavanagh, and N. Kanwisher. “Attention Response Functions: Characterizing Brain Areas Using fMRI Activation During Parametric Variations of Attentional Load.” Neuron. 2001 Nov 20; 32 (4): 737-45.

_PubMed abstract: _ We derived attention response functions for different cortical areas by plotting neural activity (measured by fMRI) as a function of attentional load in a visual tracking task. In many parietal and frontal cortical areas, activation increased with load over the entire range of loads tested, suggesting that these areas are directly involved in attentional processes. However, in other areas (FEF and parietal area 7), strong activation was observed even at the lowest attentional load (compared to a passive baseline using identical stimuli), but little or no additional activation was seen with increasing load. These latter areas appear to play a different role, perhaps supporting task-relevant functions that do not vary with load, such as the suppression of eye movements.

Scholl, B. J., and Z. W. Pylyshyn. “Tracking Multiple Objects Through Occlusion: Clues to Visual Objecthood.” Cognitive Psychology 38 (1999): 259-290.

_PubMed abstract: _ In three experiments, subjects attempted to track multiple items as they moved independently and unpredictably about a display. Performance was not impaired when the items were briefly (but completely) occluded at various times during their motion, suggesting that occlusion is taken into account when computing enduring perceptual objecthood. Unimpaired performance required the presence of accretion and deletion cues along fixed contours at the occluding boundaries. Performance was impaired when items were present on the visual field at the same times and to the same degrees as in the occlusion conditions, but disappeared and reappeared in ways which did not implicate the presence of occluding surfaces (e.g., by imploding and exploding into and out of existence instead of accreting and deleting along a fixed contour). Unimpaired performance did not require visible occluders (i.e., Michotte’s tunnel effect) or globally consistent occluder positions. We discuss implications of these results for theories of objecthood in visual attention. Copyright 1999 Academic Press.

Yantis, S. “Multi-element Visual Tracking: Attention and Perceptual Organization.” Cognitive Psychology 24 (1992): 295-340.

_PubMed abstract: _ Two types of theories have been advanced to account for how attention is allocated in performing goal-directed visual tasks. According to location-based theories, visual attention is allocated to spatial locations in the image; according to object-based theories, attention is allocated to perceptual objects. Evidence for the latter view comes from experiments demonstrating the importance of perceptual grouping in selective-attention tasks. This article provides further evidence concerning the importance of perceptual organization in attending to objects. In seven experiments, observers tracked multiple randomly moving visual elements under a variety of conditions. Ten elements moved continuously about the display for several seconds; one to five of them were designated as targets before movement initiation. At the end of movement, one element was highlighted, and subjects indicated whether or not it was a target. The ease with which the elements in the target set could be perceptually grouped was systematically manipulated. In Experiments 1-3, factors that influenced the initial formation of a perceptual group were manipulated; this affected performance, but only early in practice. In Experiments 4-7, factors that influenced the maintenance of a perceptual group during motion were manipulated; this affected performance throughout practice. The results suggest that observers spontaneously grouped the target elements and directed attention toward this coherent but nonrigid virtual object. This supports object-based theories of attention and demonstrates that perceptual grouping, which is usually conceived of as a purely stimulus-driven process, can also be governed by goal-directed mechanisms.

2.Object Perception in Infants: an Encapsulated Mechanism?

Johnson, S. P., and R. N. Aslin. “Perception of Object Unity in Young Infants: The Roles of Motion, Depth and Orientation.” Cognitive Development 11 (1996): 161-180.

Johnson, S. P., J. G. Bremner, A. Slater, and U. Mason. “The Role of Good Form in Young Infants’ Perception of Partly Occluded Objects.” Journal of Experimental Child Psychology 76 (2000): 1-25.

_PubMed abstract: _ Young infants have been reported to perceive the unity of a center-occluded object when the visible ends of the object undergo common motion, but not on the basis of stationary information (e.g., P. J. Kellman & E. S. Spelke, 1983). We investigated the possibility that 4-month-old infants will attend to and utilize the global configuration (i.e., the “good form”) of a partly occluded, moving object to perceive its unity and coherence behind the occluder. In the first experiment, infants viewed a partly occluded circle or cross that translated laterally. Infants who habituated in the minimum number of trials (“fast habituators”) showed a reliable posthabituation preference for a broken object over a complete object, indicating perception of unity in the habituation display. Slow habituators exhibited no posthabituation preference. In the second experiment, infants were presented with small ring and cross displays, and the infants looked longer at the broken object. There were no reliable differences in performance between fast and slow habituators. A control group demonstrated no reliable posthabituation preference. In three additional conditions, infants viewed either a partly occluded half ring or a display in which two rod parts were either relatable and nonaligned or nonrelatable. The results indicated that curvature per se provided information in support of completion, in addition to global configuration and motion. Implications for theories of infants’ visual development are discussed. Copyright 2000 Academic Press.

Jusczyk, P. W., S. P. Johnson, E. S. Spelke, and L. J. Kennedy. “Synchronous Change and Perception of Object Unity: Evidence from Adults and Infants.” Cognition 71 (1999): 257-288.

_PubMed abstract: _ Adults and infants display a robust ability to perceive the unity of a center-occluded object when the visible ends of the object undergo common motion (e.g. Kellman, P.J., Spelke, E.S., 1983. Perception of partly occluded objects in infancy. Cognitive Psychology 15, 483-524). Ecologically oriented accounts of this ability focus on the primary of motion in the perception of segregated objects, but Gestalt theory suggests a broader possibility: observers may perceive object unity by detecting patterns of synchronous change, of which common motion is a special case. We investigated this possibility with observations of adults and 4-month-old infants. Participants viewed a center-occluded object whose visible surfaces were either misaligned or aligned, stationary or moving, and unchanging or synchronously changing in color or brightness in various temporal patterns (e.g. flashing). Both alignment and common motion contributed to adults’ perception of object unity, but synchronous color changes did not. For infants, motion was an important determinant of object unity, but other synchronous changes and edge alignment were not. When a stationary object with aligned edges underwent synchronous changes in color or brightness, infants showed high levels of attention to the object, but their perception of its unity appeared to be indeterminate. An inherent preference for fast over slow flash rates, and a novelty preference elicited by a change in rate, both indicated that infants detected the synchronous changes, although they failed to use them as information for object unity. These findings favor ecologically oriented accounts of object perception in which surface motion plays a privileged role.

3. Object Tracking in Infants and Adults: A Domain-specific Mechanism?

Chiang, W. C., and K. Wynn. “Infants’ Tracking of Objects and Collections.” Cognition 77 (2000): 169-195.

_PubMed abstract: _ Recent research suggests that infants’ understanding of the physical world is more complex and adult-like than previously believed. One of the most impressive discoveries has been infants’ ability to reason about medium-sized, material objects. They are able to individuate objects in a scene, and to enumerate and reason about them. This article reports a series of experiments investigating 8-month-old infants’ ability to reason about collections of objects. Experiment 1 shows a sharp contrast between infants’ understanding of single objects versus collections. While infants detected the discontinuous (‘Magical’) disappearance of a single object, they did not detect the Magical Disappearance of a non-cohesive pile of objects. Experiments 2-4 found that infants’ difficulty remained even when the distinct identity of each object in the collection was emphasized, but could be overcome if infants (a) first saw the individual objects clearly separated from each other prior to their being placed together in a pile, or (b) had prior experience with the objects making up the collection. Our findings suggest that infants’ expectations about object behavior are highly specific regarding the entities they are applied to. They do not automatically apply to any and all portions of matter within the visual field. Both the behavior of an entity, and infants’ prior experience play roles in determining whether infants will treat that entity as an object.

Scholl, B. J., Z. W. Pylyshyn, and J. Feldman. “What is a Visual Object? Evidence from Target Merging in Multiple Object Tracking.” Cognition 80 (2001): 159-77.

_PubMed abstract: _ The notion that visual attention can operate over visual objects in addition to spatial locations has recently received much empirical support, but there has been relatively little empirical consideration of what can count as an ‘object’ in the first place. We have investigated this question in the context of the multiple object tracking paradigm, in which subjects must track a number of independently and unpredictably moving identical items in a field of identical distractors. What types of feature clusters can be tracked in this manner? In other words, what counts as an ‘object’ in this task? We investigated this question with a technique we call target merging: we alter tracking displays so that distinct target and distractor locations appear perceptually to be parts of the same object by merging pairs of items (one target with one distractor) in various ways - for example, by connecting item locations with a simple line segment, by drawing the convex hull of the two items, and so forth. The data show that target merging makes the tracking task far more difficult to varying degrees depending on exactly how the items are merged. The effect is perceptually salient, involving in some conditions a total destruction of subjects’ capacity to track multiple items. These studies provide strong evidence for the object-based nature of tracking, confirming that in some contexts attention must be allocated to objects rather than arbitrary collections of features. In addition, the results begin to reveal the types of spatially organized scene components that can be independently attended as a function of properties such as connectedness, part structure, and other types of perceptual grouping.

Van de Walle, G., J. Rubenstein, and E. S. Spelke. “Infant Sensitivity to Shadow Motions.” Cognitive Development 13 (1998): 387-419.

4. Infants’ Use or Non-use of Kind Information to Parse Objects

Carey, S., and F. Xu. “Infants’ Knowledge of Objects: Beyond Object Files and Object Tracking.” Cognition 80 (2001): 179-213.

_PubMed abstract: _ Two independent research communities have produced large bodies of data concerning object representations: the community concerned with the infant’s object concept and the community concerned with adult object-based attention. We marshal evidence in support of the hypothesis that both communities have been studying the same natural kind. The discovery that the object representations of young infants are the same as the object files of mid-level visual cognition has implications for both fields.

Needham, A., and R. Baillargeon. “Infants’ Use of Featural and Experiential Information in Segregating and Individuating Objects: a Reply to Xu, Carey & Welch (1999).” Cognition 74 (2000): 255-284.

Xu, F., S. Carey, and J. Welch. “Infants’ Ability to Use Object Kind Information for Object Individuation.” Cognition 70 (1999): 137-166.

_PubMed abstract: _ The present studies investigate infants reliance on object kind information in solving the problem of object individuation. Two experiments explored whether adults, 10- and 12-month-old infants could use their knowledge of ducks and cars to individuate an ambiguous array consisting of a toy duck perched on a toy car into two objects. A third experiment investigated whether 10-month-old infants could use their knowledge of cups and shoes to individuate an array consisting of a cup perched on a shoe into two objects. Ten-month-old infants failed to use object kind information alone to resolve the ambiguity with both pairs of objects. In contrast, infants this age succeeded in using spatiotemporal information to segment the array into two objects, i.e. they succeeded if shown that the duck moved independently relative to the car, or the cup relative to the shoe. Twelve-month-old infants, as well as adults, succeeded at object individuation on the basis of object kind information alone. These findings shed light on the developmental course of object individuation and provide converging evidence for the Object-first Hypothesis [Xu, F., Carey, S., 1996; Xu, F., 1997b]. Early on, infants may represent only one concept that provides criteria for individuation, namely physical object; kind concepts such as duck, car, cup, and shoe may be acquired later in the first year of life.

5. Adults’ Use or Non-use of Kind Information to Parse Objects

Marr, D. Vision. Freeman, 1982, pp. 270-271.

Peterson, M. A., B. de Gelder, S. Z. Rapcsak, P. C. Gerhardstein, and A. Bachoud-Levi. “Object Memory Effects on Figure Assignment: Conscious Object Recognition is Not Necessary or Sufficient.” Vision Research 40 (2000): 1549-1567.

_PubMed abstract: _ In three experiments we investigated whether conscious object recognition is necessary or sufficient for effects of object memories on figure assignment. In experiment 1, we examined a brain-damaged participant, AD, whose conscious object recognition is severely impaired. AD’s responses about figure assignment do reveal effects from memories of object structure, indicating that conscious object recognition is not necessary for these effects, and identifying the figure-ground test employed here as a new implicit test of access to memories of object structure. In experiments 2 and 3, we tested a second brain-damaged participant, WG, for whom conscious object recognition was relatively spared. Nevertheless, effects from memories of object structure on figure assignment were not evident in WG’s responses about figure assignment in experiment 2, indicating that conscious object recognition is not sufficient for effects of object memories on figure assignment. WG’s performance sheds light on AD’s performance, and has implications for the theoretical understanding of object memory effects on figure assignmentRiddoch, J., and G. W. Humphreys. “Visual Object Processing in Optic Aphasia: A Case of Semantic Access Agnosia.” Cognitive Neuropsychology 4 (1987): 131-185.

PEOPLE I: FACES

General readings:

Moscovitch, M., G. Winocur, and M. Behrmann. “What is Special About Face Recognition? Nineteen Experiments on a Person with Visual Object Agnosia and Dyslexia but Normal Face Recognition.” Journal of Cognitive Neuroscience 9 (1997): 555-604.

Tanaka, J. W., and M. J. Farah. “Parts and Wholes in Face Recognition.” Q J Exp Psychol A 46 (1993): 225-45.

_PubMed abstract: _ Are faces recognized using more holistic representations than other types of stimuli? Taking holistic representation to mean representation without an internal part structure, we interpret the available evidence on this issue and then design new empirical tests. Based on previous research, we reasoned that if a portion of an object corresponds to an explicitly represented part in a hierarchical visual representation, then when that portion is presented in isolation it will be identified relatively more easily than if it did not have the status of an explicitly represented part. The hypothesis that face recognition is holistic therefore predicts that a part of a face will be disproportionately more easily recognized in the whole face than as an isolated part, relative to recognition of the parts and wholes of other kinds of stimuli. This prediction was borne out in three experiments: subjects were more accurate at identifying the parts of faces, presented in the whole object, than they were at identifying the same part presented in isolation, even though both parts and wholes were tested in a forced-choice format and the whole faces differed only by one part. In contrast, three other types of stimuli–scrambled faces, inverted faces, and houses–did not show this advantage for part identification in whole object recognition.

and one of the following sets of readings:

1. On the Nature of Face Representations

Rhodes, G., S. Carey, G. Byatt, and F. Proffitt. “Coding Spatial Variations in Faces and Simple Shapes: a Test of Two Models.” Vision Res 38 (1998): 2307-2321.

Young, A. W., D. Hellawell, and D. C. Hay. “Configurational Information in Face Perception.” Perception 16, 6 (1987): 747-59.

_PubMed abstract: _ A new facial composites technique is demonstrated, in which photographs of the top and bottom halves of different familiar faces fuse to form unfamiliar faces when aligned with each other. The perception of a novel configuration in such composite stimuli is sufficiently convincing to interfere with identification of the constituent parts (experiment 1), but this effect disappears when stimuli are inverted (experiment 2). Difficulty in identifying the parts of upright composites is found even for stimuli made from parts of unfamiliar faces that have only ever been encountered as face fragments (experiment 3). An equivalent effect is found for composites made from internal and external facial features of well-known people (experiment 4). These findings demonstrate the importance of configurational information in face perception, and that configurations are only properly perceived in upright faces.

2. Evidence for Special Neural Hardware for Faces

Allison, T., A. Puce, D. D. Spencer, and G. McCarthy. “Electrophysiological Studies of Human Face Perception. I: Potentials Generated in Occipitotemporal Cortex by Face and Non-face Stimuli.” Cereb Cortex 9 (1999): 415-30.

_PubMed abstract: _ This and the following two papers describe event-related potentials (ERPs) evoked by visual stimuli in 98 patients in whom electrodes were placed directly upon the cortical surface to monitor medically intractable seizures. Patients viewed pictures of faces, scrambled faces, letter-strings, number-strings, and animate and inanimate objects. This paper describes ERPs generated in striate and peristriate cortex, evoked by faces, and evoked by sinusoidal gratings, objects and letter-strings. Short-latency ERPs generated in striate and peristriate cortex were sensitive to elementary stimulus features such as luminance. Three types of face-specific ERPs were found: (i) a surface-negative potential with a peak latency of approximately 200 ms (N200) recorded from ventral occipitotemporal cortex, (ii) a lateral surface N200 recorded primarily from the middle temporal gyrus, and (iii) a late positive potential (P350) recorded from posterior ventral occipitotemporal, posterior lateral temporal and anterior ventral temporal cortex. Face-specific N200s were preceded by P150 and followed by P290 and N700 ERPs. N200 reflects initial face-specific processing, while P290, N700 and P350 reflect later face processing at or near N200 sites and in anterior ventral temporal cortex. Face-specific N200 amplitude was not significantly different in males and females, in the normal and abnormal hemisphere, or in the right and left hemisphere. However, cortical patches generating ventral face-specific N200s were larger in the right hemisphere. Other cortical patches in the same region of extrastriate cortex generated grating-sensitive N180s and object-specific or letter-string-specific N200s, suggesting that the human ventral object recognition system is segregated into functionally discrete regions.

Kanwisher, N., P. Downing, R. Epstein, and Z. Kourtzi. “Functional Neuroimaging of Visual Recognition.” In Handbook of Functional Neuroimaging. Edited by Cabeza and Kingstone. MIT Press, pp. 117-125.

Sergent, J., and J. Signoret. “Varieties of Functional Deficits in Prosopagnosia.” Cerebral Cortex 2 (1992): 375-388.

_PubMed abstract: _ Prosopagnosia is a neurologically based deficit characterized by the inability to recognize faces of known individuals in the absence of severe intellectual, perceptual, and memory impairments. The nature of the underlying disturbance was investigated in three patients in an attempt to identify the structural and functional levels at which the processing of faces breaks down, the relation between prosopagnosia and associated deficits, and the specificity of the prosopagnosic disturbance. The breakdown of face processing resulted from unilateral damage in different cerebral structures of the right hemisphere in the three patients, and it involved different functional levels of face processing, but all three patients displayed perceptual impairments of unequal severity. In one patient (R.M.), the deficit encompassed all perceptual operations on faces, including matching identical views of the same faces, but it did not extend to all categories of objects characterized by a close similarity among their instances; the second patient (P.M.) exhibited a less severe perceptual impairment but was unable to derive the configurational properties from a facial representation and to extract its physiognomic invariants; the third patient (P.C.) had not lost the capacity to differentiate faces on the basis of their configurations but could not associate a facial representation with its pertinent memories. Associated deficits were present in each patient but differed depending on the anatomofunctional locus of the breakdown, although all patients were impaired at recognizing noncanonical views of objects that they readily recognized when shown from a conventional viewpoint. However, performance dissociation within patients and double dissociation between patients suggest that these associated deficits are not necessary concomitants of prosopagnosia.

3. The Role of Experience

Diamond, R., and S. Carey. “Why Faces Are and Are Not Special: An Effect of Expertise.” Journal of Experimental Psychology: General 115 (1986): 107-117.

_PubMed abstract: _ Recognition memory for faces is hampered much more by inverted presentation than is memory for any other material so far examined. The present study demonstrates that faces are not unique with regard to this vulnerability to inversion. The experiments also attempt to isolate the source of the inversion effect. In one experiment, use of stimuli (landscapes) in which spatial relations among elements are potentially important distinguishing features is shown not to guarantee a large inversion effect. Two additional experiments show that for dog experts sufficiently knowledgeable to individuate dogs of the same breed, memory for photographs of dogs of that breed is as disrupted by inversion as is face recognition. A final experiment indicates that the effect of orientation on memory for faces does not depend on inability to identify single features of these stimuli upside down. These experiments are consistent with the view that experts represent items in memory in terms of distinguishing features of a different kind than do novices. Speculations as to the type of feature used and neuropsychological and developmental implications of this accomplishment are offered.

Kanwisher, N. “Domain Specificity in Face Perception.” Nat Neurosci 3 (2000): 759-63.

Tarr, M. J., and I. Gauthier. “FFA: a Flexible Fusiform Area for Subordinate-level Visual Processing Automatized by Expertise.” Nat Neurosci 3 (2000): 764-9.

4. Category-General Object Representation

Grill-Spector, et al. “The Lateral Occipital Complex and its Role in Object Recognition.” Vision Research 41 (2001): 1409-1422.

_PubMed abstract: _ Here we review recent findings that reveal the functional properties of extra-striate regions in the human visual cortex that are involved in the representation and perception of objects. We characterize both the invariant and non-invariant properties of these regions and we discuss the correlation between activation of these regions and recognition. Overall, these results indicate that the lateral occipital complex plays an important role in human object recognition.

Haxby, J. V., E. A. Hoffman, and M. I. Gobbini. “The Distributed Human Neural System for Face Perception.” Trends Cogn Sci 4 (2000): 223-233.

Haxby, J. V., M. I. Gobbini, M. L. Furey, A. Ishai, J. L. Schouten, and P. Pietrini. “Distributed and Overlapping Representations of Faces and Objects in Ventral Temporal Cortex.” Science 293 (2001): 2425-2430.

_PubMed abstract: _ Face perception, perhaps the most highly developed visual skill in humans, is mediated by a distributed neural system in humans that is comprised of multiple, bilateral regions. We propose a model for the organization of this system that emphasizes a distinction between the representation of invariant and changeable aspects of faces. The representation of invariant aspects of faces underlies the recognition of individuals, whereas the representation of changeable aspects of faces, such as eye gaze, expression, and lip movement, underlies the perception of information that facilitates social communication. The model is also hierarchical insofar as it is divided into a core system and an extended system. The core system is comprised of occipitotemporal regions in extrastriate visual cortex that mediate the visual analysis of faces. In the core system, the representation of invariant aspects is mediated more by the face-responsive region in the fusiform gyrus, whereas the representation of changeable aspects is mediated more by the face-responsive region in the superior temporal sulcus. The extended system is comprised of regions from neural systems for other cognitive functions that can be recruited to act in concert with the regions in the core system to extract meaning from faces.

5. Developmental Origins of Face Recognition Abilities

Duchaine, B. “Developmental Prosopagnosia with Normal Configural Processing.” Neuroreport 11 (2000): 79-83.

_PubMed abstract: _ The configural processing hypothesis proposes that prosopagnosia results from a domain-general impairment in configural processing, and so predicted that all prosopagnosics would have impaired configural processing. In order to test this prediction, tests of face recognition and configural processing were presented to a developmental prosopagnosic. He was severely impaired in face recognition, but his normal performance on three tests of configural processing disconfirmed the configural processing hypothesis. Additional tests of low-level vision and object recognition found no evidence of impairments with material other than faces. The pattern of spared and impaired face recognition indicates that this case of developmental prosopagnosia is caused by a domain-specific inability to match novel views of faces with previously derived representations.

Farah, M., C. Rabinowitz, G. E. Quinn, and G. Liu. “Early Commitment of Neural Substrates for Face Recognition.” Cognitive Neuropsychology 17 (2000): 117-123.

Le Grand, R., C. J. Mondloch, D. Maurer, and H. P. Brent. “Neuroperception. Early Visual Experience and Face Processing.” Nature 410, 6831 (2001): 890.

Rodman, H. R. “Development of Inferior Temporal Cortex in the Monkey.” Cereb Cortex 4 (1994): 484-98. Review.

_PubMed abstract: _ Inferior temporal (IT) cortex is critical for visual pattern recognition in adult primates. However, the functional development of IT cortex appears to be incomplete until late in the first year of life in monkeys and probably beyond. Responses of neurons in IT are substantially weaker, of longer latency, and more susceptible to anesthesia within at least the first half year of life. In addition, refinement of connections of IT, particularly those with regions in the opposite hemisphere and with regions related to memory and attention, continues for at least several months after birth. Moreover, many of the pattern recognition functions that IT supports in adulthood themselves show a very protracted period of development, and damage to IT cortex in infancy appears to have relatively little effect on pattern recognition abilities, despite the pronounced effects of comparable damage in adulthood. These findings all suggest that IT undergoes an extended period of postnatal development, during which both visual experience and the maturation of other brain structures may contribute to the emergence of mechanisms of pattern recognition within IT. In other respects, fundamental characteristics of IT emerge quite early. For example, despite their weaker responses, IT neurons have adult-like patterns of responsiveness–including pronounced form selectivity and large bilateral receptive fields–as early as we were able to test (approximately 6 weeks). Thus, IT cortex appears to be prewired with (or predisposed to develop rapidly) neural circuitry sufficient to produce basic properties remarkably similar to those found in the adult animal. Future studies of IT cortex will need to address the development of signals related to perceptual constancies and to formation and retrieval of visual object memories, the development of interactions with other regions involved in visual recognition (particularly frontal cortex), and the specific mechanisms underlying various types of plasticity present in IT cortex in both developing and mature primates.

PEOPLE II: BODY PARTS, BIOLOGICAL MOTION, AND ACTION

General readings:

Adolphs, R. “Social cognition and the human brain.” Trends Cogn Sci 3 (1999): 469-479.

_PubMed abstract: _ Humans are exceedingly social animals, but the neural underpinnings of social cognition and behavior are not well understood. Studies in humans and other primates have pointed to several structures that play a key role in guiding social behaviors: the amygdala, ventromedial frontal cortices, and right somatosensory-related cortex, among others. These structures appear to mediate between perceptual representations of socially relevant stimuli, such as the sight of conspecifics, and retrieval of knowledge (or elicitation of behaviors) that such stimuli can trigger. Current debates concern the extent to which social cognition draws upon processing specialized for social information, and the relative contributions made to social cognition by innate and acquired knowledge.

Downing, P. E., Y. Jiang, M. Shuman, and N. Kanwisher. “A Cortical Area Selective for Visual Processing of the Human Body.” Science 293 (2001): 2470-2473.

_PubMed abstract: _ Despite extensive evidence for regions of human visual cortex that respond selectively to faces, few studies have considered the cortical representation of the appearance of the rest of the human body. We present a series of functional magnetic resonance imaging (fMRI) studies revealing substantial evidence for a distinct cortical region in humans that responds selectively to images of the human body, as compared with a wide range of control stimuli. This region was found in the lateral occipitotemporal cortex in all subjects tested and apparently reflects a specialized neural system for the visual perception of the human body.

and one of the following sets of readings:

1. Body Parts

Buxbaum, L. J., and H. B. Coslett. “Specialized Structural Descriptions for Human Body Parts: Evidence from Autopagnosia.” Cognitive Neuropsychology 18 (2001): 289-306.

Levinson, S. C. “Vision, Shape, and Linguistic Description: Tzeltal Body-part Terminology and Object Description.” Linguistics 32 (1994): 791-855.

2. Biological Motion

Bertenthal, B. I. “Infants’ Perception of Biomechanical Motions: Intrinsic Image and Knowledge Based Constraints.” In Visual Perception and Cognition in Infancy. Edited by C. Granrud. Erlbaum, 1993, pp.175-214.

Grossman, E., M. Donnelly, R. Price, D. Pickens, V. Morgan, G. Neighbor, and R. Blake. “Brain Areas Involved in Perception of Biological Motion.” J Cogn Neurosci 12 (2000): 711-20.

_PubMed abstract: _ These experiments use functional magnetic resonance imaging (fMRI) to reveal neural activity uniquely associated with perception of biological motion. We isolated brain areas activated during the viewing of point-light figures, then compared those areas to regions known to be involved in coherent-motion perception and kinetic-boundary perception. Coherent motion activated a region matching previous reports of human MT/MST complex located on the temporo-parieto-occipital junction. Kinetic boundaries activated a region posterior and adjacent to human MT previously identified as the kinetic-occipital (KO) region or the lateral-occipital (LO) complex. The pattern of activation during viewing of biological motion was located within a small region on the ventral bank of the occipital extent of the superior-temporal sulcus (STS). This region is located lateral and anterior to human MT/MST, and anterior to KO. Among our observers, we localized this region more frequently in the right hemisphere than in the left. This was true regardless of whether the point-light figures were presented in the right or left hemifield. A small region in the medial cerebellum was also active when observers viewed biological-motion sequences. Consistent with earlier neuroimaging and single-unit studies, this pattern of results points to the existence of neural mechanisms specialized for analysis of the kinematics defining biological motion.

3. Gaze Following

Allison, T., A. Puce, and G. McCarthy. “Social Perception from Visual Cues: Role of the STS Region.” TICS 4, 7 (2000): 267-278.

_PubMed abstract: _ Social perception refers to initial stages in the processing of information that culminates in the accurate analysis of the dispositions and intentions of other individuals. Single-cell recordings in monkeys, and neurophysiological and neuroimaging studies in humans, reveal that cerebral cortex in and near the superior temporal sulcus (STS) region is an important component of this perceptual system. In monkeys and humans, the STS region is activated by movements of the eyes, mouth, hands and body, suggesting that it is involved in analysis of biological motion. However, it is also activated by static images of the face and body, suggesting that it is sensitive to implied motion and more generally to stimuli that signal the actions of another individual. Subsequent analysis of socially relevant stimuli is carried out in the amygdala and orbitofrontal cortex, which supports a three-structure model proposed by Brothers. The homology of human and monkey areas involved in social perception, and the functional interrelationships between the STS region and the ventral face area, are unresolved issues.

Hood, B. M., J. D. Willen, and J. Driver. “Adult’s Eyes Trigger Shifts of Visual Attention in Human Infants.” Psychological Science 9 (1998): 131-134.

Vecera, S., and M. Johnson. “Gaze Detection and the Cortical Processing of Faces: Evidence from Infants and Adults.” Visual Cognition 2 (1995): 59-97.

4. Mirror Neurons and Imitation

Rizzolatti, G., L. Logassi, and V. Gallese. “Cortical Mechanisms Subserving Object Grasping and Action Recognition: A New View on the Cortical Motor Functions.” In The New Cognitive Neurosciences. Edited by M. S. Gazzaniga. 2nd ed. MIT Press, 2000, pp. 539-552.

Tomasello, M., and J. Call. Primate Cognition. Oxford Press, 1997, chap. 9.

5. Perceiving Action as Goal-directed

Emery, and Perrett. “How Can Studies of the Monkey Brain Help Us Understand Theory of Mind and Autism in Humans?” In Understanding Other Minds: Perspectives From Developmental Neuroscience. Edited by S. Baron-Cohen, H. Tager-Flusberg and D. Cohen. Oxford University Press, 2000, pp. 274-305.

Johnson, S. “The Recognition of Mentalistic Agents in Infancy.” TICS 4 (2000): 22-28.

_PubMed abstract: _ The ability to construe ourselves and others as agents with minds having mental states such as perceptions, attention, desires and beliefs, is critical to humans’ social, linguistic, and cognitive competence. When and how this ability becomes available to us during development is therefore of particular theoretical importance. Historically, most work in this area has concentrated on the ability of three- and four-year-olds to predict and explain behaviors based on false beliefs. With recent advances in the methods available for studying cognition in pre-verbal infants however, more research is now focused on earlier age groups. In this review, arguments are presented for and against the presence of a rudimentary ’theory of mind’ in infancy, with evidence discussed from three sources: (1) infants’ active interactions with people; (2) infants’ passive observations of people; and (3) infants’ interactions with, and observations, of non-human agents.

Woodward, A. “Infants Selectively Encode the Goal Object of an Actor’s Reach.” Cognition 69 (1998): 1-34.

PEOPLE III: MIND

General readings:

Fodor, J. A. “A Theory of the Child’s Theory of mind.” Cognition 44 (1992): 283-296.

Leslie, A. “ToMM, ToBY, and Agency: Core Knowledge and Domain Specificity.” In Mapping The Mind: Domain Specificity In Cognition And Culture. Edited by L. A. Hirschfeld and S. A. Gelman. Cambridge, UK: Cambridge University Press, 1994, pp. 119-148.

and one of the following sets of readings:

1. Theory of Mind and Language

deVilliers, J. “Language and Theory of Mind: What are the Developmental Relationships?” In Understanding Other Minds: Perspectives From Developmental Cognitive Neuroscience. Edited by S. Baron-Cohen, H. Tager-Flusberg and D. J. Cohen. 2nd ed. Oxford Press, 2000.

Siegal, M., R. Varley, and S. C. Want. “Mind Over Grammar: Reasoning in Aphasia and Development.” Trends Cogn Sci 5, 7 (2001): 296-301.

_PubMed abstract: _ Research on propositional reasoning (involving ’theory of mind’ understanding) in adult patients with aphasia reveals that reasoning can proceed in the absence of explicit grammatical knowledge. Conversely, evidence from studies with deaf children shows that the presence of such knowledge is not sufficient to account for reasoning. These findings are in keeping with recent research on the development of naming, categorization and imitation, indicating that children’s reasoning about objects and actions is guided by inferences about others’ communicative intentions. We discuss the extent to which reasoning is supported by, and tied to, language in the form of conversational awareness and experience rather than grammar.

2. Theory of Mind and Autism: A Specific Deficit?

Baron-Cohen, S. “Theory of Mind and Autism: a fifteen-year Review.” In Understanding Other Minds: Perspectives From Developmental Cognitive Neuroscience. Edited by S. Baron-Cohen, H. Tager-Flusberg and D. J. Cohen. 2nd ed. Oxford Press, 2000.

Leslie, A. M., and L. Thaiss. “Domain Specificity in Conceptual Development: Neuropsychological Evidence from Autism.” Cognition 43 (1992): 225-251.

_PubMed abstract: _ To understand some aspects of conceptual development it is necessary to take cognitive architecture into account. For this purpose, the study of normal development is often not sufficient. Fortunately, one can also study neurodevelopmental disorders. For example, autistic children have severe difficulties developing certain kinds of concepts but not others. We find that whereas autistic children perform very poorly on tests of the concept, believes, they are at or near ceiling on comparable tasks that test understanding of pictorial representation. A similar pattern was found in a second study which looked at understanding of a false map or diagram: normal 4-year-olds showed a marked advantage in understanding a false belief over a false map, while the autistic subjects performed better on the map. These findings suggest that the concept, believes, develops as a domain-specific notion that is not equatable with “having a picture (map or diagram) in the head.” This result supports the existence of a specialized cognitive mechanism, which subserves the development of folk psychological notions, and which is dissociably damaged in autism. We extend these ideas to outline a new model of the development of false belief performance.

Tager-Flusberg, H., J. Boshart, and S. Baron-Cohen. “Reading the Windows to the Soul: Evidence of Domain Specific Sparing in William’s Syndrome.” JCN 10, 5 (1998): 631-639.

_PubMed abstract: _ This study tested the hypothesis that Williams syndrome, a rare genetic neurodevelopmental disorder with an unusual cognitive phenotype, involves spared abilities in the domain of understanding other minds. A group of retarded adults with Williams syndrome was compared to an age-, IQ-, and language-matched group of adults with Prader-Willi syndrome, another genetic disorder without the cognitive characteristics of Williams syndrome, and a group of age-matched normal adults, on a task that taps mentalizing ability. The task involved selecting the correct labels to match photographs of complex mental state expressions in the eye region of the face. The adults with Williams syndrome performed significantly better than the adults with Prader-Willi on this task, and about half the group performed in the same range as the normal adults. These findings are consistent with anecdotal evidence about Williams syndrome and provide evidence that mentalizing is a distinct cognitive domain. This spared cognitive capacity may be linked to the relative sparing of limbic-cerebellar neural substrate in Williams syndrome, which is also connected to cortico-frontal regions that are known to be involved in understanding complex mental states.

3. Is Theory of Mind Specific to Humans?

Hare, B., J. Call, and M. Tomasello. “Do Chimpanzees Know What Conspecifics Know?” Animal Behaviour 61, 1 (2001): 139-151.

_PubMed abstract: _ We conducted three experiments on social problem solving by chimpanzees, Pan troglodytes. In each experiment a subordinate and a dominant individual competed for food, which was placed in various ways on the subordinate’s side of two opaque barriers. In some conditions dominants had not seen the food hidden, or food they had seen hidden was moved elsewhere when they were not watching (whereas in control conditions they saw the food being hidden or moved). At the same time, subordinates always saw the entire baiting procedure and could monitor the visual access of their dominant competitor as well. If subordinates were sensitive to what dominants did or did not see during baiting, they should have preferentially approached and retrieved the food that dominants had not seen hidden or moved. This is what they did in experiment 1 when dominants were either uninformed or misinformed about the food’s location. In experiment 2 subordinates recognized, and adjusted their behaviour accordingly, when the dominant individual who witnessed the hiding was replaced with another dominant individual who had not witnessed it, thus demonstrating their ability to keep track of precisely who has witnessed what. In experiment 3 subordinates did not choose consistently between two pieces of hidden food, one of which dominants had seen hidden and one of which they had not seen hidden. However, their failure in this experiment was likely to be due to the changed nature of the competition under these circumstances and not to a failure of social-cognitive skills. These findings suggest that at least in some situations (i.e. competition with conspecifics) chimpanzees know what conspecifics have and have not seen (do and do not know), and that they use this information to devise effective social-cognitive strategies.

Hare, B., J. Call, B. Agnetta, and M. Tomasello. “What Chimpanzees Do and Do Not See.” Animal Behaviour 59, 4 (2000): 771-785.

Povinelli, D. J. “Theory of Mind: Evolutionary History of a Cognitive Specialization.” Trends in Neurosciences 18 (1995): 418-424.

_PubMed abstract: _ Traditional analyses of the evolution of intelligence have emphasized commonality and continuity among species. However, recent research suggests that humans might have specialized in a particular kind of intelligence that is related to understanding mental states such as desires, intentions and beliefs. Data indicate that the ability to reflect on one’s own mental states, as well as those of others, might be the result of evolutionary changes in the prefrontal cortex. Behavioral studies in children and chimpanzees reveal both similarities and striking differences in the developmental pathways that lead to theory-of-mind capacities. Humans and great apes share many ancient patterns of social behavior, but it is too early to be certain if they interpret them in the same manner. Humans might have evolved a cognitive specialization in theory of mind, forever altering their view of the social universe.

4. Neuroimaging of Theory of Mind

Castelli, F., F. Happe, U. Frith, and C. Frith. “Movement and Mind: A Functional Imaging Study of Perception and Interpretation of Complex Intentional Movement Patterns.” Neuroimage 12, 3 (Sep. 2000): 314-25.

_PubMed abstract: _ We report a functional neuroimaging study with positron emission tomography (PET) in which six healthy adult volunteers were scanned while watching silent computer-presented animations. The characters in the animations were simple geometrical shapes whose movement patterns selectively evoked mental state attribution or simple action description. Results showed increased activation in association with mental state attribution in four main regions: medial prefrontal cortex, temporoparietal junction (superior temporal sulcus), basal temporal regions (fusiform gyrus and temporal poles adjacent to the amygdala), and extrastriate cortex (occipital gyrus). Previous imaging studies have implicated these regions in self-monitoring, in the perception of biological motion, and in the attribution of mental states using verbal stimuli or visual depictions of the human form. We suggest that these regions form a network for processing information about intentions, and speculate that the ability to make inferences about other people’s mental states evolved from the ability to make inferences about other creatures’ actions.

Gallagher, H. L., F. Happe, N. Brunswick, P. C. Fletcher, U. Frith, and C. D. Frith. “Reading the Mind in Cartoons and Stories: an fMRI Study of ‘Theory of Mind’ in Verbal and Nonverbal Tasks.” Neuropsychologia 38, 1 (2000): 11-21.

_PubMed abstract: _ Previous functional imaging studies have explored the brain regions activated by tasks requiring ’theory of mind’–the attribution of mental states. Tasks used have been primarily verbal, and it has been unclear to what extent different results have reflected different tasks, scanning techniques, or genuinely distinct regions of activation. Here we report results from a functional magnetic resonance imaging study (fMRI) involving two rather different tasks both designed to tap theory of mind. Brain activation during the theory of mind condition of a story task and a cartoon task showed considerable overlap, specifically in the medial prefrontal cortex (paracingulate cortex). These results are discussed in relation to the cognitive mechanisms underpinning our everyday ability to ‘mind-read’.

NUMBER I: NUMBER SENSE

General readings:

Dehaene, S. The Number Sense. 1997, Chap. 5.

Dehaene, S., and L. Cohen. “Cerebral Pathways for Calculation: Double Dissociation Between Rote Verbal and Quantitative Knowledge of Arithmetic.” Cortex 33 (1997): 219-250.

_PubMed abstract: _ We describe two acalculic patients, one with a left subcortical lesion and the other with a right inferior parietal lesion and Gerstmann’s syndrome. Both suffered from “pure anarithmetia”: they could read arabic numerals and write them to dictation, but experienced a pronounced calculation deficit. On closer analysis, however, distinct deficits were found. The subcortical case suffered from a selective deficit of rote verbal knowledge, including but not limited to arithmetic tables, while her semantic knowledge of numerical quantities was intact. Conversely the inferior parietal case suffered from a category-specific impairment of quantitative numerical knowledge, particularly salient in subtraction and number bissection tasks, with preserved knowledge of rote arithmetic facts. This double dissociation suggests that numerical knowledge is processed in different formats within distinct cerebral pathways. We suggest that a left subcortical network contributes to the storage and retrieval of rote verbal arithmetic facts, while a bilateral inferior parietal network is dedicated to the mental manipulation of numerical quantities.

Gallistel, C. R., and R. Gelman. “Non-verbal Numerical Cognition: From Reals to Integers.” Trends Cogn Sci 4 (2000): 59-65.

_PubMed abstract: _ Data on numerical processing by verbal (human) and non-verbal (animal and human) subjects are integrated by the hypothesis that a non-verbal counting process represents discrete (countable) quantities by means of magnitudes with scalar variability. These appear to be identical to the magnitudes that represent continuous (uncountable) quantities such as duration. The magnitudes representing countable quantity are generated by a discrete incrementing process, which defines next magnitudes and yields a discrete ordering. In the case of continuous quantities, the continuous accumulation process does not define next magnitudes, so the ordering is also continuous (‘dense’). The magnitudes representing both countable and uncountable quantity are arithmetically combined in, for example, the computation of the income to be expected from a foraging patch. Thus, on the hypothesis presented here, the primitive machinery for arithmetic processing works with real numbers (magnitudes).

and one of the following sets of readings:

1. Is there a Dedicated Cortical Region for Processing Approximate Numerosity?

Cohen, L., S. Dehaene, F. Chochon, S. Lehericy, and L. Naccache. “Language and Calculation within the Parietal Lobe: A Combined Cognitive, Anatomical and fMRI Study.” Neuropsychologia 38 (2000): 1426-1440.

_PubMed abstract: _ We report the case of a patient (ATH) who suffered from aphasia, deep dyslexia, and acalculia, following a lesion in her left perisylvian area. She showed a severe impairment in all tasks involving numbers in a verbal format, such as reading aloud, writing to dictation, or responding verbally to questions of numerical knowledge. In contrast, her ability to manipulate non-verbal representations of numbers, i.e., Arabic numerals and quantities, was comparatively well preserved, as evidenced for instance in number comparison or number bisection tasks. This dissociated impairment of verbal and non-verbal numerical abilities entailed a differential impairment of the four arithmetic operations. ATH performed much better with subtraction and addition, that can be solved on the basis of quantity manipulation, than with multiplication and division problems, that are commonly solved by retrieving stored verbal sequences. The brain lesion affected the classical language areas, but spared a subset of the left inferior parietal lobule that was active during calculation tasks, as demonstrated with functional MRI. Finally, the relative preservation of subtraction versus multiplication may be related to the fact that subtraction activated the intact right parietal lobe, while multiplication activated predominantly left-sided areas.

Pinel, P., D. Riviere, D. Le Bihan, and S. Dehaene. “Modulation of Parietal Activation by Semantic Distance in a Number Comparison Task.” Neuroimage. 2001 Nov; 14 (5): 1013-26.

_PubMed abstract: _ The time to compare two numbers shows additive effects of number notation and of semantic distance, suggesting that the comparison task can be decomposed into distinct stages of identification and semantic processing. Using event-related fMRI and high-density ERPs, we isolated cerebral areas where activation was influenced by input notation (verbal or Arabic notation). The bilateral extrastriate cortices and a left precentral region were more activated during verbal than during Arabic stimulation, while the right fusiform gyrus and a set of bilateral inferoparietal and frontal regions were more activated during Arabic than during verbal stimulation. We also identified areas that were influenced solely by the semantic content of the stimuli (numerical distance between numbers to be compared) independent of the input notation. Activation tightly correlated with numerical distance was observed mainly in a group of parietal areas distributed bilaterally along the intraparietal sulci and in the precuneus, as well as in the left middle temporal gyrus and posterior cingulate. Our results support the assumption of a central semantic representation of numerical quantity that relies on a common parietal network shared among notations. Copyright 2001 Academic Press.

2. Number Sense in Animals

Church, R. M., and H. A. Broadbent. “Alternative Representations of Time, Number, and Rate.” Cognition 37 (1990): 55-81. (Section on number at the end of article only).

_PubMed abstract: _ Three facts of time perception are described based upon a temporal generalization task for rats (the peak procedure) in which food reinforcement is delivered on half the trials following the first lever-press response after some fixed interval after signal onset. (1) The mean response rate as a function of time is a smooth, slightly asymmetric, function with a maximum near the time of reinforcement; (2) the response rate on individual trials is characterized by an abrupt change from a state of low responding to a state of high responding and finally another state of low responding (break-run-break pattern); and (3) the mean response rate in 12-s and 20-s peak procedures is similar when plotted against time relative to the time of reinforcement (superposition). An information-processing version of scalar timing theory is described and compared to an alternative connectionist version of scalar timing theory that involves multiple oscillators and an autoassociation network. Psychological, mathematical and biological descriptions of the two versions are described and some possible extensions of the connectionist version are proposed to deal with perception of number, rate, and spatial orientation.

Davis, H., and R. Perusse. “Numerical Competence in animals: Definitional Issues, Current Evidence and a New Research Agenda.” Behavioral and Brain Sciences 11 (1988): 561-615.

Meck, W. H., and R. M. Church. “A Mode Control Model of Counting and Timing Processes.” Journal of Experimental Psychology: Animal Behavior Processes 9, 3 (1983): 320-334.

_PubMed abstract: _ The similarity of animal counting and timing processes was demonstrated in four experiments that used a psychophysical choice procedure. In Experiment 1, rats initially learned a discrimination between a two-cycle auditory signal of 2-sec duration and an eight-cycle auditory signal of 8-sec duration. For the number discrimination test, the number of cycles was varied, and the signal duration was held constant at an intermediate value. For the duration discrimination test, the signal duration was varied, and the number of cycles was held constant at an intermediate value. Rats were equally sensitive to a 4:1 ratio of counts (with duration controlled) and a 4:1 ratio of times (with number controlled). The point of subjective equality for the psychophysical functions that related response classification to signal value was near the geometric mean of the extreme values for both number and duration discriminations. Experiment 2 demonstrated that 1.5 mg/kg of methamphetamine administered intraperitoneally shifted the psychophysical functions for both number and duration leftward by approximately 10%. Experiment 3 demonstrated that the magnitude of cross-modal transfer from auditory signals to cutaneous signals was similar for number and duration. In Experiment 4 the mapping of number onto duration demonstrated that a count was approximately equal to 200 msec. The psychophysical functions for number and duration were fit with a scalar expectancy model with the same parameter values for each attribute. The conclusion was that the same internal mechanism is used for counting and timing. This mechanism can be used in several modes: the “event” mode for counting or the “run” and the “stop” modes for timing.

3. Number Sense in Infants

Brannon, E. “The Development of Ordinal Numerical Knowledge in Infancy.” Cognition. 2002 Apr; 83 (3): 223-40.

_PubMed abstract: _ A critical question in cognitive science concerns how numerical knowledge develops. One essential component of an adult concept of number is ordinality: the greater than and less than relationships between numbers. Here it is shown in two experiments that 11-month-old infants successfully discriminated, whereas 9-month-old infants failed to discriminate, sequences of numerosities that descended in numerical value from sequences that increased in numerical value. These results suggest that by 11 months of age infants possess the ability to appreciate the greater than and less than relations between numerical values but that this ability develops between 9 and 11 months of age. In an additional experiment 9-month-old infants succeeded at discriminating the ordinal direction of sequences that varied in the size of a single square rather than in number, suggesting that a capacity for non-numerical ordinal judgments may develop before a capacity for ordinal numerical judgments. These data raise many questions about how infants represent number and what happens between 9 and 11 months to support ordinal numerical judgments

Xu, F., and E. S. Spelke. “Large Number Discrimination in 6-Month-Old Infants.” Cognition 74 (2000): B1-B11.

_PubMed abstract: _ Six-month-old infants discriminate between large sets of objects on the basis of numerosity when other extraneous variables are controlled, provided that the sets to be discriminated differ by a large ratio (8 vs. 16 but not 8 vs. 12). The capacities to represent approximate numerosity found in adult animals and humans evidently develop in human infants prior to language and symbolic counting.

4. Number Sense in Adults: Estimating and Operating on Approximate Numerosities

Cordes, S., R. Gelman, C. R. Gallistel, and J. Whalen. Counting While Talking: New Evidence for Nonverbal Counting in Human Adults. (In press).

Van Oeffelen, M. P., and P. G. Vos. “A Probabilistic Model for the Discrimination of Visual Number.” Perception & Psychophysics 32 (1982): 163-170.

Whalen, J., C. R. Gallistel, and R. Gelman. “Nonverbal Counting in Humans: The Psychophysics of Number Representation.” Psychological Science 10, 2 (1999): 130-137.

5. Using Number Sense in Mental Arithmetic

Barth, H., N. Kanwisher, and E. Spelke. Non-symbolic Arithmetic with Large Approximate Numerosities. (In prep).

Dehaene, S., E. Spelke, P. Pinel, R. Stanescu, and S. Tsivkin. “Sources of Mathematical Thinking: Behavioral and Brain-imaging Evidence.” Science 284 (1999): 970-974.

_PubMed abstract: _ Does the human capacity for mathematical intuition depend on linguistic competence or on visuo-spatial representations? A series of behavioral and brain-imaging experiments provides evidence for both sources. Exact arithmetic is acquired in a language-specific format, transfers poorly to a different language or to novel facts, and recruits networks involved in word-association processes. In contrast, approximate arithmetic shows language independence, relies on a sense of numerical magnitudes, and recruits bilateral areas of the parietal lobes involved in visuo-spatial processing. Mathematical intuition may emerge from the interplay of these brain systems

Temple, E., and M. I. Posner. “Brain Mechanisms of Quantity are Similar in 5-Year-Olds and Adults.” Proceedings of the National Academy of Sciences USA 95 (1998): 7836-7841.

_PubMed abstract: _ Both 5-year-old children and adults determine the quantity of a number by the use of a similar parietal lobe mechanism. Event related potentials indicate that input from Arabic digits and from dot patterns reach areas involved in determining quantity about 200 ms after input. However, voluntary key presses indicating the relation of the input to the quantity five take almost three times as long in children. The ability to trace the networks of brain areas involved in the learning of school subjects should aid in the design and testing of educational methods.

6. Impairments of Number Sense

Butterworth, B. What Counts: How Every Brain Is Hardwired for Math. New York: Free Press, 1999, Chap. 6.

Dehaene, S., G. Dehaene-Lambertz, and L. Cohen. “Abstract Representations of Numbers in the Animal and Human Brain.” Trends in Neurosciences 21, 8 (1998): 355-361.

_PubMed abstract: _ There is evidence to suggest that animals, young infants and adult humans possess a biologically determined, domain-specific representation of number and of elementary arithmetic operations. Behavioral studies in infants and animals reveal number perception, discrimination and elementary calculation abilities in non-verbal organisms. Lesion and brain-imaging studies in humans indicate that a specific neural substrate, located in the left and right intraparietal area, is associated with knowledge of numbers and their relations (’number sense’). The number domain is a prime example where strong evidence points to an evolutionary endowment of abstract domain-specific knowledge in the brain because there are parallels between number processing in animals and humans.The numerical distance effect, which refers to the finding that the ability to discriminate between two numbers improves as the numerical distance between them increases, has been demonstrated in humans and animals, as has the number size effect,which refers to the finding that for equal numerical distance,discrimination of two numbers worsens as their numerical size increases.

Warrington, E. K. “The Fractionation of Arithmetical Skills: A Single Case Study.” Quarterly Journal of Experimental Psychology 34A (1982): 31-51.

NUMBER II: SMALL NUMBERS, LARGE NUMBERS, AND VERBAL COUNTING

General readings:

Butterworth, B. What Counts: How Every Brain Is Hardwired for Math. New York: Free Press 1999, Chap. 4.

Spelke, E. S. “Core Knowledge.” American Psychologist 55 (2000): 1233-1243.

_PubMed abstract: _ Compex cognitive skills such as reading and calculation and complex cognitive achievements such as formal science and mathematics may depend on a set of building block systems that emerge early in human ontogeny and phylogeny. These core knowledge systems show characteristic limits of domain and task specificity: Each serves to represent a particular class of entities for a particular set of purposes. By combining representations from these systems, however, human cognition may achieve extraordinary flexibility. Studies of cognition in human infants and in nonhuman primates therefore may contribute to understanding unique features of human knowledge.

Wynn, K. “Psychological Foundations of Number: Numerical Competence in Human Infants.” Trends Cogn Sci 2 (1998): 296-303.

and one of the following sets of readings:

1. Small Number Representations in Animals and Infants

Feigenson, L., M. Hauser, and S. Carey. “The Representations Underlying Infants’ Choice of More: Object-files vs. Analog Magnitudes.” Psychological Science. (In press-b).

_PubMed abstract: _ A new choice task was used to explore infants’ spontaneous representations of more and less. Ten- and 12-month-old infants saw crackers placed sequentially into two containers, then were allowed to crawl and obtain the crackers from the container they chose. Infants chose the larger quantity with comparisons of 1 versus 2 and 2 versus 3, but failed with comparisons of 3 versus 4, 2 versus 4, and 3 versus 6. Success with visible arrays ruled out a motivational explanation for failure in the occluded 3-versus-6 condition. Control tasks ruled out the possibility that presentation duration guided choice, and showed that presentation complexity was not responsible for the failure with larger numbers. When crackers were different sizes, total surface area or volume determined choice. The infants ‘pattern of success and failure supports the hypothesis that they relied on object-file representations, comparing mental models via total volume or surface area rather than via one-to-one correspondence between objectfiles.

Hauser, M., S. Carey, and L. Hauser. “Spontaneous Number Representation in Semi-Free-Ranging Rhesus Monkeys.” Proceedings of the Royal Society, London 267 (2000): 829-833.

_PubMed abstract: _ Previous research has shown that animals possess considerable numerical abilities. However, this work was based on experiments involving extensive training, a small number of captive subjects and relatively artificial testing procedures. We present the results of experiments on over 200 semi-free-ranging rhesus monkeys using a task which involves no training and mimics a natural foraging problem. The subjects observed two experimenters place pieces of apple, one at a time, into each of two opaque containers. The experimenters then walked away so that the subjects could approach. The monkeys chose the container with the greater number of apple slices when the comparisons were one versus two, two versus three, three versus four and three versus five slices. They failed at four versus five, four versus six, four versus eight and three versus eight slices. Controls established that it was the representation of number which underlay their successful choices rather than the amount of time spent placing apple pieces into the box or the volume of apple placed in the box. The failures at values greater than three slices stand in striking contrast to other animal studies where training was involved and in which far superior numerical abilities were demonstrated. The range of success achieved by rhesus monkeys in this spontaneous-number task matches the range achieved by human infants and corresponds to the range encoded in the syntax of natural languages.

Sulkowski, G. M., and M. D. Hauser. “Can Rhesus Monkeys Spontaneously Subtract?” Cognition 79 (2001): 239-262.

_PubMed abstract: _ Animals, including pigeons, parrots, raccoons, ferrets, rats, New and Old World monkeys, and apes are capable of numerical computations. Much of the evidence for such capacities is based on the use of techniques that require training. Recently, however, several studies conducted under both laboratory and field conditions have employed methods that tap spontaneous numerical representations in animals, including human infants. In this paper, we present the results of 11 experiments exploring the capacity of semi-free-ranging adult rhesus monkeys to spontaneously compute (i.e. single trial, no training) the outcome of subtraction events. In the basic design, we present one quantity of objects on one stage, a second quantity on a second stage, occlude both stages, and then remove one or no objects from each stage. Having watched these events, a subject is then allowed to approach one stage and eat the food objects behind the occluder. Results show that rhesus monkeys correctly compute the outcome of subtraction events involving three or less objects on each stage, even when the identity of the objects is different. Specifically, when presented with two food quantities, rhesus monkeys select the larger quantity following subtractions of one piece of food from two or three; this preference is maintained when subjects must distinguish food from non-food subtractions, and when food is subtracted from either one or both initial quantities. Furthermore, rhesus monkeys are capable of representing zero as well as equality when two identical quantities are contrasted. Results are discussed in light of recent attempts to determine how number is represented in the brains of animals lacking language.

2. Small Number Representations in Adults and Infants (subitizing)

Dehaene-Lambertz, G., A. Patalano, M. Pena, and S. Dehaene. “Cerebral Correlates of Number Discrimination in Infants.” (Unpublished).

Mandler, G., and B. J. Shebo. “Subitizing: An Analysis of its Component Processes.” Journal of Experimental Psychology: General 111 (1982): 1-22.

Trick, L. M., and Z. W. Pylyshyn. “Why are Small and Large Numbers Enumerated Differently? A Limited-capacity Preattentive Stage in Vision.” Psychological Review 101, 1 (1994): 80-102.

_PubMed abstract: _ “Subitizing,” the process of enumeration when there are fewer than 4 items, is rapid (40-100 ms/item), effortless, and accurate. “Counting,” the process of enumeration when there are more than 4 items, is slow (250-350 ms/item), effortful, and error-prone. Why is there a difference in the way the small and large numbers of items are enumerated? A theory of enumeration is proposed that emerges from a general theory of vision, yet explains the numeric abilities of preverbal infants, children, and adults. We argue that subitizing exploits a limited-capacity parallel mechanism for item individuation, the FINST mechanism, associated with the multiple target tracking task (Pylyshyn, 1989; Pylyshyn & Storm, 1988). Two kinds of evidence support the claim that subitizing relies on preattentive information, whereas counting requires spatial attention. First, whenever spatial attention is needed to compute a spatial relation (cf. Ullman, 1984) or to perform feature integration (cf. Treisman & Gelade, 1980), subitizing does not occur (Trick & Pylyshyn, 1993a). Second, the position of the attentional focus, as manipulated by cue validity, has a greater effect on counting than subitizing latencies (Trick & Pylyshyn, 1993b).

3. Small Number Representations in Infants: Is it Really Number?

Feigenson, L., S. Carey, and E. S. Spelke. “Infants’ Discrimination of Number vs. Continuous Extent.” Cognitive Psychology. (In press-a).

_PubMed abstract: _ Seven studies explored the empirical basis for claims that infants represent cardinal values of small sets of objects. Many studies investigating numerical ability did not properly control for continuous stimulus properties such as surface area, volume, contour length, or dimensions that correlate with these properties. Experiment 1 extended the standard habituation/dishabituation paradigm to a 1 vs 2 comparison with three-dimensional objects and confirmed that when number and total front surface area are confounded, infants discriminate the arrays. Experiment 2 revealed that infants dishabituated to a change in front surface area but not to a change in number when the two variables were pitted against each other. Experiments 3 through 5 revealed no sensitivity to number when front surface area was controlled, and Experiments 6 and 7 extended this pattern of findings to the Wynn (1992) transformation task. Infants’ lack of a response to number, combined with their demonstrated sensitivity to one or more dimensions of continuous extent, supports the hypothesis that the representations subserving object-based attention, rather than those subserving enumeration, underlie performance in the above tasks.

Simon, T. J. “Reconceptualizing the Origins of Number Knowledge: A ‘Non-numerical Account.’ " Cognitive Development 12 (1997): 349-372.

4. Patient Studies of Small Number Representations?

Dehaene, S., and L. Cohen. “Dissociable Mechanisms of Subitizing and Counting: Neuropsychological Evidence from Simultanagnosic Patients.” JEP: Human Perception and Performance 20 (1994): 958-975.

_PubMed abstract: _ Do people have to count to determine visual numerosity, or is there a fast “subitizing” procedure dedicated to small sets of 1-3 items? Numerosity naming time and errors were measured in 5 simultanagnosic patients who suffered from severe difficulties in serial counting. Although these patients made close to 100% errors in quantifying sets comprising more than 3 items, they were excellent at quantifying sets of 1, 2, and sometimes 3 items. Their performances in visual search tasks suggested that they suffered from a deficit of serial visual exploration, due to a fundamental inability to use spatial tags to keep track of previously explored locations. The present data suggest that the patients’ preserved subitizing abilities were based not on serial processing but rather on a parallel algorithm dedicated to small numerosities. Several ways in which this parallel subitizing algorithm might function are discussed.

5. Number and Language

Lemer, C., J. Leybaert, and A. Content. The Effect of Phonological Length of Multi-digit Mental Addition. (Unpublished).

Spelke, E. S., and S. Tsivkin. “Language and Number: A Bilingual Training Study.” Cognition 78 (2001): 45-88.

_PubMed abstract: _ Three experiments investigated the role of a specific language in human representations of number. Russian-English bilingual college students were taught new numerical operations (Experiment 1), new arithmetic equations (Experiments 1 and 2), or new geographical or historical facts involving numerical or non-numerical information (Experiment 3). After learning a set of items in each of their two languages, subjects were tested for knowledge of those items, and new items, in both languages. In all the studies, subjects retrieved information about exact numbers more effectively in the language of training, and they solved trained problems more effectively than untrained problems. In contrast, subjects retrieved information about approximate numbers and non-numerical facts with equal efficiency in their two languages, and their training on approximate number facts generalized to new facts of the same type. These findings suggest that a specific, natural language contributes to the representation of large, exact numbers but not to the approximate number representations that humans share with other mammals. Language appears to play a role in learning about exact numbers in a variety of contexts, a finding with implications for practice in bilingual education. The findings prompt more general speculations about the role of language in the development of specifically human cognitive abilities.

6. Are Large, Exact Number Representations Unique to Humans with Language?

Brannon, E. M., and H. S. Terrace. “Representation of the Numerosities 1-9 by Rhesus Macaques (Macaca mulatta).” Journal of Experimental Psychology: Animal Behavior Processes 26 (2000): 31-49.

_PubMed abstract: _ Three rhesus monkeys (Macaca mulatta) were trained to respond to exemplars of 1, 2, 3, and 4 in an ascending, descending, or a nonmonotonic numerical order (1–>2–>3–>4, 4–>3–>2–1, 3–>1–>4–>2). The monkeys were then tested on their ability to order pairs of the novel numerosities 5-9. In Experiment 1, all 3 monkeys ordered novel exemplars of the numerosities 1-4 in ascending or descending order. The attempt to train a nonmonotonic order (3–>1–>4–>2) failed. In Experiment 2A, the 2 monkeys who learned the ascending numerical rule ordered pairs of the novel numerosities 5-9 on unreinforced trials. The monkey who learned the descending numerical rule failed to extrapolate the descending rule to new numerosities. In Experiment 2B all 3 monkeys ordered novel exemplars of pairs of the numerosities 5-9. Accuracy and latency of responding revealed distance and magnitude effects analogous to previous findings with human participants (R. S. Moyer & T. K. Landaeur, 1967). Collectively these studies show that monkeys represent the numerosities 1-9 on at least an ordinal scale

Matzusawa, T. “Use of Numbers by a Chimpanzee.” Nature 315 (1985): 57-59.

PLACES I: PATH INTEGRATION AND COGNITIVE MAPS

General readings:

Burgess, N., K. J. Jeffery, and J. O’Keefe. “Integrating Hippocampal and Parietal Functions: A Spatial Point of View.” In The Hippocampal and Parietal Foundations of Spatial Cognition. Edited by N. Burgess, K. J. Jeffery and J. O’Keefe. London, UK: The Royal Society, 1999.

Gallistel, C. R. “Animal cognition: The Representation of Space, Time, and Number.” Annual Review of Psychology 40 (1989): 155-189. Esp. sections 1-3.

Wehner, R., and R. Menzel. “Do Insects Have Cognitive Maps?” Annual Review of Neuroscience 13 (1990): 403-413.

and one of the following sets of readings:

1. Patient Studies

Aguirre, G. K., and M. D’Esposito. “Environmental Knowledge is Subserved by Separable Dorsal/Ventral Neural Areas.” J Neurosci 17 (1997): 2512-8.

_PubMed abstract: _ Environmental psychology models propose that knowledge of large-scale space is stored as distinct landmark (place appearance) and survey (place position) information. Studies of brain-damaged patients suffering from “topographical disorientation” tentatively support this proposal. In order to determine if the components of psychologically derived models of environmental representation are realized as distinct functional, neuroanatomical regions, a functional magnetic resonance imaging (fMRI) study of environmental knowledge was performed. During scanning, subjects made judgments regarding the appearance and position of familiar locations within a virtual reality environment. The fMRI data were analyzed in a manner that has been empirically demonstrated to rigorously control type I error and provide optimum sensitivity, allowing meaningful results in the single subject. A direct comparison of the survey position and landmark appearance conditions revealed a dorsal/ventral dissociation in three of four subjects. These results are discussed in the context of the observed forms of topographical disorientation and are found to be in good agreement with the human lesion studies. This experiment confirms that environmental knowledge is not represented by a unitary system but is instead functionally distributed across the neocortex.

Worsley, C. L., M. Recce, H. J. Spiers, J. Marley, C. E. Polkey, and R. G. Morris. “Path Integration Following Temporal Lobectomy in Humans.” Neuropsychologia 39 (2001): 452-64.

_PubMed abstract: _ Path integration, a component of spatial navigation, is the process used to determine position information on the basis of information about distance and direction travelled derived from self-motion cues. Following on from studies in the animal literature that seem to support the role of the hippocampal formation in path integration, this facility was investigated in humans with focal brain lesions. Thirty-three neurosurgical patients (17 left temporal lobectomy, LTL; 16 right temporal lobectomy, RTL) and 16 controls were tested on a number of blindfolded tasks designed to investigate path integration and on a number of additional control tasks (assessing mental rotation and left-right orientation). In a test of the ability to compute a homing vector, the subjects had to return to the start after being led along a route consisting of two distances and one turn. Patients with RTL only were impaired at estimating the turn required to return to the start. On a second task, route reproduction was tested by requiring the subjects to reproduce a route consisting of two distances and one turn; the RTL group only were also impaired at reproducing the turn, but this impairment did not correlate with the homing vector deficit. There were no group differences on tasks where subjects were required to reproduce a single distance or a single turn. The results indicate that path integration is impaired in RTL patients only and suggest that the right temporal lobe plays a role in idiothetic spatial memory.

2. Path Integration in Animals

Collett, T. S. “Insect maps.” Trends in Neurosciences 10 (1987): 139-141.

Wehner, R., and S. Wehner. “Insect Navigation: Use of Maps or Ariadne’s Thread?” Ethology, Ecology & Evolution 2 (1990): 27-48.

3. Path Integration in Human Adults

Berthoz, A., I. Israel, P. G. Francois, R. Grasso, and T. Tsuzuku. “Spatial Memory of Body Linear Displacement: What is Being Stored?” Science 269 (1995): 95-98.

_PubMed abstract: _ The ability to evaluate traveled distance is common to most animal species. Head trajectory in space is measured on the basis of the converging signals of the visual, vestibular, and somatosensory systems, together with efferent copies of motor commands. Recent evidence from human studies has shown that head trajectory in space can be stored in spatial memory. A fundamental question, however, remains unanswered: How is movement stored? In this study, humans who were asked to reproduce passive linear whole-body displacement distances while blindfolded were also able to reproduce velocity profiles. This finding suggests that a spatiotemporal dynamic pattern of motion is stored and can be retrieved with the use of vestibular and somesthetic cues.

Fukusima, S. S., J. M. Loomis, and J. A. Da Silva. “Visual Perception of Egocentric Distance as Assessed by Triangulation.” Journal of Experimental Psychology: Human Perception and Performance 23 (1997): 86-100.

_PubMed abstract: _ Two triangulation methods for measuring perceived egocentric distance were examined. In the triangulation-by-pointing procedure, the observer views a target at some distance and, with eyes closed, attempts to point continuously at the target while traversing a path that passes by it. In the triangulation-by-walking procedure, the observer views a target and, with eyes closed, traverses a path that is oblique to the target; on command from the experimenter, the observer turns and walks toward the target. Two experiments using pointing and 3 using walking showed that perceived distance, averaged over observers, was accurate out to 15 m under full-cue conditions. For target distances between 15 and 25 m, the evidence indicates slight perceptual underestimation. Results also show that observers, on average, were accurate in imaginally updating the locations of previously viewed targets.

4. Updating vs. Using Allocentric Cognitive Maps

Farrell, M. J., and I. H. Robertson. “Mental Rotation and the Automatic Updating of Body-centered Spatial Relationships.” Journal of Experimental Psychology: Learning, Memory, and Cognition 24 (1998): 227-233.

Wang, R. F., and E. S. Spelke. “Updating Egocentric Representations in Human Navigation.” Cognition 77 (2000): 215-50.

_PubMed abstract: _ Seven experiments tested whether human navigation depends on enduring representations, or on momentary egocentric representations that are updated as one moves. Human subjects pointed to unseen targets, either while remaining oriented or after they had been disoriented by self-rotation. Disorientation reduced not only the absolute accuracy of pointing to all objects (‘heading error’) but also the relative accuracy of pointing to different objects (‘configuration error’). A single light providing a directional cue reduced both heading and configuration errors if it was present throughout the experiment. If the light was present during learning and test but absent during the disorientation procedure, however, subjects showed low heading errors (indicating that they reoriented by the light) but high configuration errors (indicating that they failed to retrieve an accurate cognitive map of their surroundings). These findings provide evidence that object locations are represented egocentrically. Nevertheless, disorientation had little effect on the coherence of pointing to different room corners, suggesting both (a) that the disorientation effect on representations of object locations is not due to the experimental paradigm and (b) that room geometry is captured by an enduring representation. These findings cast doubt on the view that accurate navigation depends primarily on an enduring, observer-free cognitive map, for humans construct such a representation of extended surfaces but not of objects. Like insects, humans represent the egocentric distances and directions of objects and continuously update these representations as they move. The principal evolutionary advance in animal navigation may concern the number of unseen targets whose egocentric directions and distances can be represented and updated simultaneously, rather than a qualitative shift in navigation toward reliance on an allocentric map.

5. fMRI Studies of Navigation in Virtual Environments

Maguire, E. A., N. Burgess, J. G. Donnett, R. S. Frackowiak, C. D. Frith, and J. O’Keefe. “Knowing Where and Getting There: A Human Navigation Network.” Science 280 (1998): 921-4.

_PubMed abstract: _ The neural basis of navigation by humans was investigated with functional neuroimaging of brain activity during navigation in a familiar, yet complex virtual reality town. Activation of the right hippocampus was strongly associated with knowing accurately where places were located and navigating accurately between them. Getting to those places quickly was strongly associated with activation of the right caudate nucleus. These two right-side brain structures function in the context of associated activity in right inferior parietal and bilateral medial parietal regions that support egocentric movement through the virtual town, and activity in other left-side regions (hippocampus, frontal cortex) probably involved in nonspatial aspects of navigation. These findings outline a network of brain areas that support navigation in humans and link the functions of these regions to physiological observations in other mammals.

Aguirre, G.K. “Topographical Disorientation: A Synthesis and Taxonomy.” Brain 122 (1999): 1613-28.

_PubMed abstract: _ Over the last century, several dozen case reports have presented ’topographically disoriented’ patients who, in some cases, appear to have selectively lost their ability to find their way within large-scale, locomotor environments. A review is offered here that has as its aim the creation of a taxonomy that accurately reflects the behavioural impairments and neuroanatomical findings of this literature. This effort is guided by an appreciation of the models of normative way-finding offered by environmental psychology and recent neuroscience research. It is proposed that several varieties of topographical disorientation exist, resulting from damage to distinct neuroanatomical areas. The particular pattern of impairments that patients evidence is argued to be consonant with the known functions of these cortical regions and with recent neuroimaging results. The conflicting claims of previous reviews of this area are also considered and addressed.

PLACES II: REORIENTATION

General readings:

Epstein, R., and N. Kanwisher. “A Cortical Representation of the Local Visual Environment.” Nature 392 (1998): 598-601.

_PubMed abstract: _ Medial temporal brain regions such as the hippocampal formation and parahippocampal cortex have been generally implicated in navigation and visual memory. However, the specific function of each of these regions is not yet clear. Here we present evidence that a particular area within human parahippocampal cortex is involved in a critical component of navigation: perceiving the local visual environment. This region, which we name the ‘parahippocampal place area’ (PPA), responds selectively and automatically in functional magnetic resonance imaging (fMRI) to passively viewed scenes, but only weakly to single objects and not at all to faces. The critical factor for this activation appears to be the presence in the stimulus of information about the layout of local space. The response in the PPA to scenes with spatial layout but no discrete objects (empty rooms) is as strong as the response to complex meaningful scenes containing multiple objects (the same rooms furnished) and over twice as strong as the response to arrays of multiple objects without three-dimensional spatial context (the furniture from these rooms on a blank background). This response is reduced if the surfaces in the scene are rearranged so that they no longer define a coherent space. We propose that the PPA represents places by encoding the geometry of the local environment.

O’Keefe, J., and N. Burgess. “Geometric Determinants of the Place Fields of Hippocampal Neurons.” Nature 381 (1996): 425-8.

_PubMed abstract: _ The human hippocampus has been implicated in memory, in particular episodic or declarative memory. In rats, hippocampal lesions cause selective spatial deficits, and hippocampal complex spike cells (place cells) exhibit spatially localized firing, suggesting a role in spatial memory, although broader functions have also been suggested. Here we report the identification of the environmental features controlling the location and shape of the receptive fields (place fields) of the place cells. This was done by recording from the same cell in four rectangular boxes that differed solely in the length of one or both sides. Most of our results are explained by a model in which the place field is formed by the summation of gaussian tuning curves, each oriented perpendicular to a box wall and peaked at a fixed distance from it.

Spelke, E. S. “Developing Knowledge of Space: Core Systems and New Combinations.” In Languages of the Brain. Edited by A. Galaburda and S. Kosslyn. Harvard University Press. (In press).

and one of the following sets of readings:

1. Is there a Purely Geometric Module in Animals?

Cheng, K. “A Purely Geometric Module in the Rat’s Spatial Representation.” Cognition 23 (1984): 149-178.

Dudchenko, P. A., J. P. Goodridge, D. A. Seiterle, and J. S. Taube. “Effects of Repeated Disorientation on the Acquisition of Spatial Tasks in Rats: Dissociation Between the Appetitive Radial Arm Maze and Aversive Water Maze.” Journal of Experimental Psychology: Animal Behavior Processes 23 (1997): 194-210.

_PubMed abstract: _ This study examined the effects of disorientation on the acquisition of different spatial reference memory tasks. In an appetitively motivated radial arm maze task in which 1 arm was consistently baited, rats that were disoriented before each trial were impaired in their ability to acquire the task relative to rats placed in a clear container and not disoriented. However, disoriented rats were able to learn a Morris water maze and a water version of the radial arm maze under similar training conditions, suggesting that the effects of disorientation may interact with the quality or quantity of motivation involved in a given task. These results suggest that appetitive and aversive spatial tasks are dissociable, and that any impairment that is due to disorientation is specific to the appetitive radial arm maze task.

2. Is there a Purely Geometric Module in Human Infants?

Learmonth, A., N. Newcombe, and J. Huttenlocher. “Reorientation, Landmark Use, and Size: The Fate of the Geometric Module.” Psychological Science. (In press).

Wang, R. F., L. Hermer, and E. S. Spelke. “Mechanisms of Reorientation and Object Localization by Children: A Comparison with Rats.” Behav Neurosci 113 (1999): 475-85.

_PubMed abstract: _ Neurophysiological studies show that the firing of place and head-direction (HD) cells in rats can become anchored to features of the perceptible environment, suggesting that those features partially specify the rat’s position and heading. In contrast, behavioral studies suggest that disoriented rats and human children rely exclusively on the shape of their surroundings, ignoring much of the information to which place and HD cells respond. This difference is explored in the current study by investigating young children’s ability to locate objects in a square chamber after disorientation. Children 18-24 months old used a distinctive geometric cue but not a distinctively colored wall to locate the object, even after they were familiarized with the colored wall. Results suggest that the spatial representations underlying reorientation and object localization are common to humans and other mammals. Together with the neurophysiological findings, these experiments raise questions for the hypothesis that hippocampal place and HD cells serve as a general orientation device for target localization.

3. Space and Language

Hermer-Vazquez, L., A. Moffet, and P. Munkholm. “Language, Space, and the Development of Cognitive Flexibility in Humans: The Case of Two Spatial Memory Tasks.” Cognition 79 (2001): 263-299.

_PubMed abstract: _ Prior experiments have shown that young children, like adult rats, rely mainly on information about the macroscopic shape of the environment to reorient themselves, whereas human adults rely more flexibly on combinations of spatial and non-spatial landmark information. Adult rats have also been shown to exhibit a striking limitation in another spatial memory task, movable object search, again a limitation not shown by human adults. The present experiments explored the developmental change in humans leading to more flexible, human adult-like performance on these two tasks. Experiment 1 identified the age range of 5-7 years as the time the developmental change for reorientation occurs. Experiment 2 employed a multiple regression approach to determine that among several candidate measures, only a specific language production measure, the production of phrases specifying exactly the information needed to solve the task like adults, correlated with the reorientation performance of children in this age range. Experiment 3 revealed that similar language production abilities were associated with more flexible moving object search task performance. These results, in combination with findings with human adults, suggest that language production skills play a causal role in allowing older humans to construct novel representations rapidly, which can then be used to transcend the limits of phylogenetically older cognitive processes

Hermer-Vazquez, L., E. S. Spelke, and A. S. Katsnelson. “Sources of Flexibility in Human Cognition: Dual Task Studies of Space and Language.” Cognitive Psychology 39 (1999): 3-36.

_PubMed abstract: _ Under many circumstances, children and adult rats reorient themselves through a process which operates only on information about the shape of the environment (e.g., Cheng, 1986; Hermer & Spelke, 1996). In contrast, human adults relocate themselves more flexibly, by conjoining geometric and nongeometric information to specify their position (Hermer & Spelke, 1994). The present experiments used a dual-task method to investigate the processes that underlie the flexible conjunction of information. In Experiment 1, subjects reoriented themselves flexibly when they performed no secondary task, but they reoriented themselves like children and adult rats when they engaged in verbal shadowing of continuous speech. In Experiment 2, subjects who engaged in nonverbal shadowing of a continuous rhythm reoriented like nonshadowing subjects, suggesting that the interference effect in Experiment 1 did not stem from general limits on working memory or attention but from processes more specific to language. In further experiments, verbally shadowing subjects detected and remembered both nongeometric information (Experiment 3) and geometric information (Experiments 1, 2, and 4), but they failed to conjoin the two types of information to specify the positions of objects (Experiment 4). Together, the experiments suggest that humans’ flexible spatial memory depends on the ability to combine diverse information sources rapidly into unitary representations and that this ability, in turn, depends on natural language.

4. Geometry and the Brain

Burgess, N., and J. O’Keefe. “Neuronal Computations Un derlying the Firing of Place Cells and Their Role in Navigation.” Hippocampus 6 (1996): 749-762.

_PubMed abstract: _ Our model of the spatial and temporal aspects of place cell firing and their role in rat navigation is reviewed. The model provides a candidate mechanism, at the level of individual cells, by which place cell information concerning self-localization could be used to guide navigation to previously visited reward sites. The model embodies specific predictions regarding the formation of place fields, the phase coding of place cell firing with respect to the hippocampal theta rhythm, and the formation of neuronal population vectors downstream from the place cells that code for the directions of goals during navigation. Recent experiments regarding the spatial distribution of place cell firing have confirmed our initial modeling hypothesis, that place fields are formed from Gaussian tuning curve inputs coding for the distances from environmental features, and enabled us to further specify the functional form of these inputs. Other recent experiments regarding the temporal distribution of place cell firing in two-dimensional environments have confirmed our predictions based on the temporal aspects of place cell firing on linear tracks. Directions for further experiments and refinements to the model are outlined for the future.

Wilson, M. A. “The Neural Correlates of Place and Direction.” In The New Cognitive Neurosciences. Edited by M. S. Gazzaniga. 2nd ed. MIT Press, 2000.

OTHER POSSIBLE DOMAINS

1. Animals

Bonatti, L., E. Frot, R. Zangl, and J. Mehler. “The Human First Hypothesis: Identification of Conspecifics and Individuation of Objects in the Young Infant.” Cognit Psychol. 2002 Jun; 44 (4): 388-426.

_PubMed abstract: _ How do infants individuate and track objects, and among them objects belonging to their species, when they can only rely on information about the properties of those objects? We propose the Human First Hypothesis (HFH), which posits that infants possess information about their conspecifics and use it to identify and count objects. F. Xu and S. Carey [Cognitive Psychology, 30(2), 111-153, 1996] argued that before the age of 1 year, infants fail to use property information. To explain their results, Xu and Carey proposed the Object First Hypothesis (OFH), according to which infants under 1 year of age have only the general concept of physical object to identify and count objects. We show that infants have a more extensive knowledge of sortals than that claimed by the OFH. When 10-month-olds see one humanlike and one non-humanlike object, they successfully identify and count them by using the contrast in their properties, as predicted by the HFH. We also show that infants succeed even when they make a decision based on differences between two close basic-level categories such as humanlike objects and doglike objects, but fail when they have to use differences within the human category. Thus, infants treat “human” as a basic sortal, as predicted by the HFH. We argue that our results cannot be accounted for by general purpose mechanisms. Neither the strong version of the OFH and its explanation in terms of object indexing mechanisms [A. M. Leslie, F. Xu, P. Tremoulet, & B. J. Scholl, Trends in Cognitive Sciences, 2(1), 10-18, 1998] nor explanations in terms of task demands [T. Wilcox & R. Baillargeon, Cognitive Psychology, 37(2), 97-155, 1998] are sufficient to explain our results.

Caramazza, A., and J. R. Shelton. “Domain-specific Knowledge Systems in the Brain: The Animate Inanimate Distinction.” J Cogn Neurosci 10 (1998): 1-34.

_PubMed abstract: _ We claim that the animate and inanimate conceptual categories represent evolutionarily adapted domain-specific knowledge systems that are subserved by distinct neural mechanisms, thereby allowing for their selective impairment in conditions of brain damage. On this view, (some of) the category-specific deficits that have recently been reported in the cognitive neuropsychological literature - for example, the selective damage or sparing of knowledge about animals - are truly categorical effects. Here, we articulate and defend this thesis against the dominant, reductionist theory of category-specific deficits, which holds that the categorical nature of the deficits is the result of selective damage to noncategorically organized visual or functional semantic subsystems. On the latter view, the sensory/functional dimension provides the fundamental organizing principle of the semantic system. Since, according to the latter theory, sensory and functional properties are differentially important in determining the meaning of the members of different semantic categories, selective damage to the visual or the functional semantic subsystem will result in a category-like deficit. A review of the literature and the results of a new case of category-specific deficit will show that the domain-specific knowledge framework provides a better account of category-specific deficits than the sensory/functional dichotomy theory.

2. Fruits and Vegetables

Hart, J., Jr., and R. S. Berndt, A. Caramazza. “Category-specific Naming Deficit Following Cerebral Infarction.” Nature 316 (1985): 439-40.

_PubMed abstract: _ Studies aimed at characterizing the operation of cognitive functions in normal individuals have examined data from patients with focal cerebral insult. These studies assume that brain damage impairs functions of the cognitive processes along lines that honour the ’normal’ pre-morbid organization of the cognitive system. For example, detailed study of individual brain-damaged patients has revealed apparently selective disruption of cognitive functions such as auditory/verbal working memory, phonological processing ability, grapheme-to-phoneme translation procedures and semantic processing. Warrington et al. have studied patients with even more fine-grained selective disturbances of the semantic system. The most selective deficits have been reported for four patients who were significantly better at identifying inanimate objects than they were at identifying living things and foods. These patterns of selective deficit after localized brain damage provide important information about the normal organization of the lexicon, and ultimately about how components of the lexical system are related to particular neural substrates. Here, we report a case study of a patient demonstrating a very selective disturbance of the ability to name items from two related semantic categories. Despite normal performance on a large battery of lexical/semantic tasks, the patient shows a consistent and striking disability in naming members of the semantic categories of ‘fruits’ and ‘vegetables’. The selectivity of this deficit supports a category-specific organization of the mental lexicon, and suggests independence of the processing routes involving naming and name recognition.

Santos, L., M. D. Hauser, and E. S. Spelke. “Representation of Food Kinds in the Rhesus Macaques (macaca mulatta): An Unexplored Domain of Knowledge.” Cognition. (In press).

3. Tools

Brown, A. “Domain-specific Principles Affect Learning and Transfer in Children.” Cognitive Science 14 (1990): 107-133.

Chao, L. L., J. V. Haxby, and A. Martin. “Attribute-based Neural Substrates in Temporal Cortex for Perceiving and Knowing About Objects.” Nat Neurosci 2 (1999): 913-9.

_PubMed abstract: _ The cognitive and neural mechanisms underlying category-specific knowledge remain controversial. Here we report that, across multiple tasks (viewing, delayed match to sample, naming), pictures of animals and tools were associated with highly consistent, category-related patterns of activation in ventral (fusiform gyrus) and lateral (superior and middle temporal gyri) regions of the posterior temporal lobes. In addition, similar patterns of category-related activity occurred when subjects read the names of, and answered questions about, animals and tools. These findings suggest that semantic object information is represented in distributed networks that include sites for storing information about specific object attributes such as form (ventral temporal cortex) and motion (lateral temporal cortex).

Hauser, M. D. “Artifactual Kinds and Functional Design Features: What a Primate Understands Without Language.” Cognition 64 (1997): 285-308.

_PubMed abstract: _ Of several domains of knowledge, humans appear to be born with an innately structured representational system for making sense of objects, what properties individuate them, how they move in space, and what causes them to move from one location to another. They also appear to make simple conceptual cuts between artifactual kinds and living kinds. The basis for this distinction seems to be a combination of crucial functional properties, together with a teleological (i.e., historical/intentional) stance, one that asks ‘What was this object designed for?’. Although non-human primates also appear to have considerable understanding of objects, and often use objects as tools, it is not clear whether they draw a distinction between artifactual and living kinds, and if so, what factors guide this distinction. As a step in addressing this problem, I present experiments on a small New World monkey, the cotton-top tamarin (Saguinus oedipus oedipus), designed to reveal their understanding of the functional properties of tools using a procedure associated with minimal training. Specifically, the experiments explored whether tamarins distinguish between relevant and irrelevant properties of a tool, and further, understand that some features can be transformed with little cost to functionality. The first experiment was a means-end task and involved using a cane-like object (a tool) to access a piece of food. In this experiment, there were always two choices: either the food was immediately accessible because it was located on the inside of the cane’s hook or less readily accessible because it was located on the outside of the hook. Most of the tamarins reached criterion on this task within a few sessions, consistently picking the cane with the most accessible food. Subsequent experiments (2-4) involved property changes (i.e., its color, texture, size and shape) that had either significant or relatively insignificant effects on the tool’s function. In general, the tamarins appeared tolerant of all property transformations as evidenced by the fact that they selected each object at least once. However, clear preferences also emerged suggesting that some properties had a more significant impact on the tool’s functionality. Thus, in head-to-head competitions, tools with color or texture changes were selectively preferred over tools with shape or size changes. This makes sense color and texture do not effect the tool’s function, whereas shape and size do. The final experiments involved both novel and familiar objects that, based on their current configuration, could readily be used as tools, in contrast with objects that required considerable manipulation to convert into a tool. Consistently, the tamarins preferred possible over convertible tools, and when two convertible tools were presented at the same time, they preferred the tool that required the fewest changes to the required motor response. Results suggest that the tamarins distinguish between relevant and irrelevant properties of a tool and this distinction is based on functionality, on having good design. This ability is especially surprising given the fact that tamarins do not naturally use tools, and infrequently come into contact with artifacts. Results are discussed in light of current theories concerning the representational foundations of natural kinds, and in particular, artifactual kinds.

Santos, L. R., M. D. Hauser, and E. S. Spelke. “Domain-specific Knowledge in Human Children and Non-human Primates: Artifact and Food Kinds.” In The Cognitive Animal. Edited by M. Bekoff, C. Allen and G. Burghardt. Cambridge, MA: MIT Press. (In press).

4. Predators

Mineka, S., and M. Cook. " Mechanisms Involved in the Observational Conditioning of Fear .” J. Exp. Psychology: General 122 (1993): 23-38.

_PubMed abstract: _ Three experiments support the hypothesis that mechanisms involved in observational conditioning (OC) of fear are similar to those of direct classical conditioning and involve the organism attempting to detect the causal structure of its environment. Experiment 1, a correlational analysis, shows that model monkeys’ fear behaviors on snake trials (unconditioned stimulus [US]) were highly correlated with observer monkeys’ fear (unconditioned response) while watching the models’ fear. In Experiment 2, all observers showed distress while watching the model’s fear during Session 1 of OC, but only observers who could see the snake to which the model was reacting continued to show fear during subsequent OC sessions, suggesting that the model’s fear is an easily habituable US. In Experiment 3, observers acquired significant fear of snakes after 1 OC session, indicating that the continued fear of those Experiment 2 observers that could see the snake may reflect their own acquired fear of snakes.

5. Cheaters

6. Probability

7. Moral Sense

Greene, J. D., R. B. Sommerville, L. E. Nystrom, J. M. Darley, and J. D. Cohen. “An fMRI Investigation of Emotional Engagement in Moral Judgment.” Science 293 (2001): 2105-2108.

_PubMed abstract: _ The long-standing rationalist tradition in moral psychology emphasizes the role of reason in moral judgment. A more recent trend places increased emphasis on emotion. Although both reason and emotion are likely to play important roles in moral judgment, relatively little is known about their neural correlates, the nature of their interaction, and the factors that modulate their respective behavioral influences in the context of moral judgment. In two functional magnetic resonance imaging (fMRI) studies using moral dilemmas as probes, we apply the methods of cognitive neuroscience to the study of moral judgment. We argue that moral dilemmas vary systematically in the extent to which they engage emotional processing and that these variations in emotional engagement influence moral judgment. These results may shed light on some puzzling patterns in moral judgment observed by contemporary philosophers.

8. Chairs

9. A “visual word form area”