Assignments

Assignment 5

Article: Sugita, Y. “Face Perception in Monkeys Reared with No Exposure to Faces.” PNAS 105, no. 1 (2008): 394–98. DOI: 10.1073/pnas.0706079105

Assignment: Read the assigned article carefully and think about it, then provide short answers to the questions below. Be clear and concise—points will be taken off for unnecessary words.

Notes: This is a hard assignment. Two videos that might also be helpful are:

Figs. 3a,b © 2008 National Academy of Sciences. All rights reserved. This content is excluded from our Creative Commons license, see https://ocw.mit.edu/fairuse for details. Source: Sugita. Y. Face perception in monkeys reared with no exposure to faces. PNAS Jan 2008, 105 (1) 394-398; DOI: 10.1073/pnas.0706079105

1. The above results are from a preferential looking task in monkeys. To conduct a preferential looking task, two objects or pictures are placed side by side within the subject’s field of view. The amount of time spent looking at each object/picture is measured for a fixed period. The above plots are the results of the preferential looking test described in Sugita 2008.  Describe the results and attempt to explain their importance.

Figs. 4a,b © 2008 National Academy of Sciences. All rights reserved. This content is excluded from our Creative Commons license, see https://ocw.mit.edu/fairuse for details. Source: Sugita. Y. Face perception in monkeys reared with no exposure to faces. PNAS Jan 2008, 105 (1) 394-398; DOI: 10.1073/pnas.0706079105

2. A visual paired-comparison procedure (VPC) uses habituation to determine if subjects can discriminate between pairs of stimuli in the same class.* The above plots are from Sugita 2008 and depict the results of a VPC test in face-deprived (A) and typically developed (B) monkeys. What are the key results? Explain their implications.

3. Inspired by Sugita, you decide to test whether you can find an FFA in young monkeys using fMRI. To do so, you design two different experiments described below. For each experiment first state your hypothesis based on the Sugita paper, and then your specific predictions for the following specific findings: (i) the response you might expect to see to faces compared to objects in a region of the ventral temporal cortex (approximately where you would find the FFA in adults); and (ii) the rationale behind your predictions. Feel free to use words or make simple plots. Use only what you know from class (especially the snake homework) and the Sugita paper.

a) Experiment 1: A blocked design with black and white images of faces, bodies, objects, and scenes. Each image is presented for 500 ms and each block is 18 seconds long.

b) Experiment 2: Similar to the protocol established by Sugita et al., infant monkeys are face-deprived for 6, 12, and 24 months. Similar to Experiment 1, the paradigm is a blocked design with black and white images of faces, objects, bodies and scenes. Each image is presented for 500 ms, each block is 18 seconds long, and monkeys are passively viewing the stimuli. Monkeys are scanned twice—once at the end of the face deprivation period (t = 0) and once 6 months later (t = 6).

* If this description of VPC is unclear, a more thorough explanation can be found here: Nancy’s Brain Talks: What is the role of experience in the development of face recognition?

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