WEBVTT 00:00:00.000 --> 00:00:03.992 [DIGITAL EFFECTS] 00:00:10.978 --> 00:00:13.250 NANCY KANWISHER: So let's start with one 00:00:13.250 --> 00:00:16.880 of the deepest questions humans have ever asked themselves. 00:00:16.880 --> 00:00:19.700 We're not messing around in this class; we're going for it. 00:00:19.700 --> 00:00:21.530 And one of the deepest questions is, 00:00:21.530 --> 00:00:23.870 where does knowledge come from? 00:00:23.870 --> 00:00:27.230 And as you'll know, if you've taken even a teeny bit 00:00:27.230 --> 00:00:29.600 of philosophy or read even a teeny bit, 00:00:29.600 --> 00:00:32.119 you know that some of the classic views in Western 00:00:32.119 --> 00:00:35.630 philosophy-- especially the empiricists, Locke and Hume-- 00:00:35.630 --> 00:00:41.420 argue that all knowledge comes from experience, right? 00:00:41.420 --> 00:00:43.430 On the other hand, there are a number 00:00:43.430 --> 00:00:46.820 of other schools of thought in Western philosophy, of which 00:00:46.820 --> 00:00:49.070 a dominant figure is Immanuel Kant, who 00:00:49.070 --> 00:00:51.990 argued that experience alone is not enough. 00:00:51.990 --> 00:00:55.670 You can't just have experience and figure out all the stuff 00:00:55.670 --> 00:00:57.140 we have figured out. 00:00:57.140 --> 00:00:59.960 And so he argued that there has to be what he called 00:00:59.960 --> 00:01:03.260 "a priori conditions" of cognition, which 00:01:03.260 --> 00:01:05.420 can't be derived from experience themselves, 00:01:05.420 --> 00:01:08.930 but have to be given prior to it, OK? 00:01:08.930 --> 00:01:11.330 So you have to have to build some structure into a mind 00:01:11.330 --> 00:01:13.100 or brain to get it off the ground. 00:01:13.100 --> 00:01:15.020 You can't just start with absolutely nothing 00:01:15.020 --> 00:01:16.990 and get anywhere. 00:01:16.990 --> 00:01:20.890 OK, and he also argued that one of the key elements of this 00:01:20.890 --> 00:01:23.830 a priori structure that you have to build in 00:01:23.830 --> 00:01:27.240 was space and time-- 00:01:27.240 --> 00:01:32.090 organizing principles of cognition and thinking. 00:01:32.090 --> 00:01:33.640 And so in his version of it, space 00:01:33.640 --> 00:01:37.240 is nothing but the form of all appearances of outer sense, 00:01:37.240 --> 00:01:41.380 and it can be given prior to all actual perceptions and so 00:01:41.380 --> 00:01:44.800 exist in the mind a priori, and can contain, 00:01:44.800 --> 00:01:47.860 prior to all experience, principles which determine 00:01:47.860 --> 00:01:50.840 the relations of these objects. 00:01:50.840 --> 00:01:57.230 OK, well, is that just empty philosophical hot air? 00:01:57.230 --> 00:01:59.480 It's kind of hard to understand exactly what he means. 00:01:59.480 --> 00:02:02.420 You're actually have to go spend a good deal of time 00:02:02.420 --> 00:02:05.390 with reading him to make any sense of it-- 00:02:05.390 --> 00:02:08.690 or cheat and get your friends to tell you, as I do. 00:02:08.690 --> 00:02:12.800 But no, I'll argue it's not just empty philosophical hot air-- 00:02:12.800 --> 00:02:14.840 that these are, in some important sense, 00:02:14.840 --> 00:02:16.375 empirical questions. 00:02:16.375 --> 00:02:17.750 And there are empirical questions 00:02:17.750 --> 00:02:21.770 that our field addresses very directly. 00:02:21.770 --> 00:02:23.450 And so on Wednesday, we'll talk about 00:02:23.450 --> 00:02:27.500 whether your representations of space in your head are innate 00:02:27.500 --> 00:02:28.100 or not. 00:02:28.100 --> 00:02:31.340 It's pretty much directly what Kant is talking about-- 00:02:31.340 --> 00:02:33.590 or the modern version of what he was talking about. 00:02:33.590 --> 00:02:35.840 And today, we'll talk about which aspects of the brain 00:02:35.840 --> 00:02:38.360 are innate and which our learned, OK? 00:02:38.360 --> 00:02:39.950 That's the agenda. 00:02:39.950 --> 00:02:44.728 OK, so this little kind of Easter egg brain here very 00:02:44.728 --> 00:02:46.520 schematically shows you some of the regions 00:02:46.520 --> 00:02:48.312 that we've been talking about in this class 00:02:48.312 --> 00:02:51.020 so far, with regions that are, to varying degrees, 00:02:51.020 --> 00:02:54.290 specialized for processing things like shape, and color, 00:02:54.290 --> 00:02:57.590 and motion, and faces, and places, and bodies-- 00:02:57.590 --> 00:03:00.440 visually processing all of these things in approximately 00:03:00.440 --> 00:03:02.420 those locations. 00:03:02.420 --> 00:03:05.030 And as I've mentioned, these regions 00:03:05.030 --> 00:03:07.610 are present in approximately the same location-- 00:03:07.610 --> 00:03:09.830 with some individual variability-- in pretty 00:03:09.830 --> 00:03:11.958 much every normal person. 00:03:11.958 --> 00:03:14.000 One of my lab members says, you keep saying that, 00:03:14.000 --> 00:03:14.860 and it's just not true. 00:03:14.860 --> 00:03:16.140 There's some percent of subjects who 00:03:16.140 --> 00:03:17.290 just don't show these things. 00:03:17.290 --> 00:03:18.248 He's kind of right, OK. 00:03:18.248 --> 00:03:21.307 So maybe, I don't know, 5%, 10% of subjects, 00:03:21.307 --> 00:03:22.890 you wouldn't see some of these things. 00:03:22.890 --> 00:03:24.807 And we've never actually done the serious work 00:03:24.807 --> 00:03:27.600 of bringing those subjects back, scanning the hell out of them, 00:03:27.600 --> 00:03:30.100 and finding out whether they were just asleep in the scanner 00:03:30.100 --> 00:03:32.910 or it was a bad scanner day, or whatever it was. 00:03:32.910 --> 00:03:35.370 I bet they all have them, and it's just sometimes 00:03:35.370 --> 00:03:38.430 you don't see it, but I'm trying to be a little more honest. 00:03:38.430 --> 00:03:40.920 OK, but you just look at this. 00:03:40.920 --> 00:03:42.890 Given this very schematic version of it, 00:03:42.890 --> 00:03:45.450 you say, how would you build this system? 00:03:45.450 --> 00:03:49.920 How would you start with an embryo and build into a genome, 00:03:49.920 --> 00:03:51.810 or build into whatever experience 00:03:51.810 --> 00:03:54.780 is going to happen to this developing organism? 00:03:54.780 --> 00:03:57.930 How would it end up with this very particular structure, 00:03:57.930 --> 00:04:00.570 with those things in approximately the same place-- 00:04:00.570 --> 00:04:03.960 or at least the same relative positions-- in all subjects? 00:04:03.960 --> 00:04:06.840 The face bits are always lateral to the color bits. 00:04:06.840 --> 00:04:09.630 The place bits are medial to the color bits. 00:04:09.630 --> 00:04:12.780 The shape bits are out on the lateral surface. 00:04:12.780 --> 00:04:14.520 It's like always like that. 00:04:14.520 --> 00:04:17.459 How do you build a system like that? 00:04:17.459 --> 00:04:19.769 I find it hard not to immediately think, well, 00:04:19.769 --> 00:04:21.899 some aspect of this must be innate, 00:04:21.899 --> 00:04:25.420 or how would it be so damn similar in each individual, 00:04:25.420 --> 00:04:25.920 right? 00:04:29.780 --> 00:04:32.930 But it's not the only hypothesis. 00:04:32.930 --> 00:04:37.040 Some big part of it-- even if some aspect of this is innate, 00:04:37.040 --> 00:04:39.440 some big part of it may also be learned or derived 00:04:39.440 --> 00:04:42.030 from experience, OK? 00:04:42.030 --> 00:04:43.498 So what do you guys think? 00:04:43.498 --> 00:04:45.290 Do you think the fact that these structures 00:04:45.290 --> 00:04:48.080 are in systematically the same place across subjects 00:04:48.080 --> 00:04:50.960 mean you have to build in all that stuff, 00:04:50.960 --> 00:04:53.510 somehow figure out how to get a bunch of As 00:04:53.510 --> 00:04:57.650 and Ts and Gs and Cs in your DNA to give you a blueprint for how 00:04:57.650 --> 00:04:59.620 to build that structure? 00:05:02.440 --> 00:05:03.420 What do you think? 00:05:08.170 --> 00:05:09.548 Yeah? 00:05:09.548 --> 00:05:11.090 AUDIENCE: I mean, it's a combination, 00:05:11.090 --> 00:05:14.210 but it's hard to, then, think about how that's 00:05:14.210 --> 00:05:15.980 involved in [INAUDIBLE] generation 00:05:15.980 --> 00:05:18.710 and then kind of become more innate? 00:05:18.710 --> 00:05:22.000 NANCY KANWISHER: Yeah, so to some extent, experience-- 00:05:22.000 --> 00:05:23.800 what I mean here is learn from experience 00:05:23.800 --> 00:05:25.360 within each individual. 00:05:25.360 --> 00:05:26.890 You could argue that "innate" really 00:05:26.890 --> 00:05:30.340 means "learned through the experience of our ancestors, 00:05:30.340 --> 00:05:33.850 and hence wired into the DNA," yeah. 00:05:33.850 --> 00:05:35.830 Anyway, I find this not an obvious question, 00:05:35.830 --> 00:05:39.527 and so we'll talk about what the data say here. 00:05:39.527 --> 00:05:41.860 So first of all, we're going to do some very basic facts 00:05:41.860 --> 00:05:44.193 about brain development, just to get the picture of what 00:05:44.193 --> 00:05:47.290 we're talking about physically with the development of brains. 00:05:47.290 --> 00:05:50.980 So we can ask, what is present at birth? 00:05:50.980 --> 00:05:55.030 And so it turns out that most of the neurons in the adult brain 00:05:55.030 --> 00:05:57.880 are generated before birth, OK? 00:05:57.880 --> 00:06:00.760 So most of the actual neurons are generated early. 00:06:00.760 --> 00:06:03.400 You're not making a whole lot more after birth-- 00:06:03.400 --> 00:06:05.650 a few, but not a lot. 00:06:05.650 --> 00:06:08.500 Further, the current view is that most of the long-range 00:06:08.500 --> 00:06:11.000 connections-- that means like a connection between this part 00:06:11.000 --> 00:06:12.250 and that part of the brain-- 00:06:12.250 --> 00:06:14.770 are also present at birth, OK? 00:06:17.630 --> 00:06:20.240 Nonetheless, even though a lot of stuff is present at birth, 00:06:20.240 --> 00:06:23.210 a lot of stuff changes in the first couple of years of life. 00:06:23.210 --> 00:06:25.880 Most obviously, the brain doubles in volume 00:06:25.880 --> 00:06:29.165 in the first year, from a two-week-old, 00:06:29.165 --> 00:06:31.450 to a one-year-old, to a two-year-old. 00:06:34.940 --> 00:06:38.600 The cortical thickness-- you can see here the dark stuff, 00:06:38.600 --> 00:06:41.300 which is the gray matter out there-- 00:06:41.300 --> 00:06:46.910 increases sharply between years one and two. 00:06:46.910 --> 00:06:49.610 But also, the complexity of each individual neuron 00:06:49.610 --> 00:06:52.790 increases dramatically in the first few years of life. 00:06:52.790 --> 00:06:56.060 So here's a schematic picture of a piece of gray matter here. 00:06:56.060 --> 00:06:57.650 We have some number of neurons here 00:06:57.650 --> 00:07:01.640 with a few little processes and a few connections. 00:07:01.640 --> 00:07:04.580 And over the first couple of years of life, 00:07:04.580 --> 00:07:07.610 those connections get much more dense, 00:07:07.610 --> 00:07:09.230 and the neurons get much more complex. 00:07:11.940 --> 00:07:13.400 OK, and the final thing that really 00:07:13.400 --> 00:07:18.440 matters early on in development is that myelination happens 00:07:18.440 --> 00:07:19.980 rapidly in the first few years. 00:07:19.980 --> 00:07:22.400 And remember, myelin-- this is a little reminder-- 00:07:22.400 --> 00:07:25.160 neuron with that yellow stuff, which is a bunch of cells 00:07:25.160 --> 00:07:28.970 that wrap around the axons, the long processes of a neuron. 00:07:28.970 --> 00:07:31.938 And that myelin sheath builds up a lot 00:07:31.938 --> 00:07:33.230 over the first couple of years. 00:07:33.230 --> 00:07:35.630 And that's important, because the myelin sheath enables 00:07:35.630 --> 00:07:37.940 those neurons to send their signals faster 00:07:37.940 --> 00:07:41.070 down their axons, OK? 00:07:41.070 --> 00:07:44.610 OK, and this is just a picture of different-- 00:07:44.610 --> 00:07:47.250 of a vertical slice like this through the anatomy 00:07:47.250 --> 00:07:52.530 of infants of different ages, from 107 days up to about a 00:07:52.530 --> 00:07:53.190 year. 00:07:53.190 --> 00:07:54.990 And the colored stuff in the middle 00:07:54.990 --> 00:07:57.240 is degree of myelination, which you 00:07:57.240 --> 00:07:59.760 can see with various kinds of anatomical scans. 00:07:59.760 --> 00:08:03.540 You can see it starts at 107 days with a tiny little bit 00:08:03.540 --> 00:08:06.690 in the middle, and it gets more and more myelinated 00:08:06.690 --> 00:08:09.300 and moves from center to periphery 00:08:09.300 --> 00:08:11.460 over the first year of life. 00:08:11.460 --> 00:08:14.370 So all those fiber pathways are getting 00:08:14.370 --> 00:08:19.920 accelerated as they get wrapped with myelin and hence sped up. 00:08:19.920 --> 00:08:25.020 OK, all right, so bottom line is most neurons 00:08:25.020 --> 00:08:27.210 and long-range connections are in place at birth, 00:08:27.210 --> 00:08:30.640 but development continues rapidly in the first two years, 00:08:30.640 --> 00:08:33.960 especially increasing complexity of neurons and synapses 00:08:33.960 --> 00:08:36.870 and myelination of long-range connections and white matter, 00:08:36.870 --> 00:08:37.409 OK? 00:08:37.409 --> 00:08:40.919 So it's just basic anatomy, nothing functional yet. 00:08:40.919 --> 00:08:43.350 OK, now we're going to consider in some detail 00:08:43.350 --> 00:08:46.560 the case of face perception, not really because that's 00:08:46.560 --> 00:08:48.300 what I work on-- 00:08:48.300 --> 00:08:50.130 or used to work on, mostly-- 00:08:50.130 --> 00:08:52.140 but just because there's a very rich set 00:08:52.140 --> 00:08:54.480 of data where people have grappled with this question 00:08:54.480 --> 00:08:56.190 in the case of face perception. 00:08:56.190 --> 00:08:58.590 Next time, we'll talk about the navigation network 00:08:58.590 --> 00:09:01.950 and reorientation-- what parts of that system might be innate 00:09:01.950 --> 00:09:04.058 and learned. 00:09:04.058 --> 00:09:05.850 So I'll just say right out of the beginning 00:09:05.850 --> 00:09:08.880 that this is an extremely active area, where every time I 00:09:08.880 --> 00:09:11.970 turn around, another paper comes out that contradicts 00:09:11.970 --> 00:09:13.740 a previously-published finding. 00:09:13.740 --> 00:09:16.320 And so that makes it fun, but it means 00:09:16.320 --> 00:09:18.653 there isn't going to be some really tight, perfect story 00:09:18.653 --> 00:09:19.153 here. 00:09:19.153 --> 00:09:21.720 And I'd rather take you guys straight to the cutting edge, 00:09:21.720 --> 00:09:26.310 even though it's kind of a mess, than give you a nicely packaged 00:09:26.310 --> 00:09:28.740 but surely wrong picture, OK? 00:09:28.740 --> 00:09:31.228 Because again, I think what matters most in this area 00:09:31.228 --> 00:09:33.270 is how do you go about answering these questions, 00:09:33.270 --> 00:09:36.900 rather than what is the current state of the thoughts 00:09:36.900 --> 00:09:37.680 about the answers. 00:09:37.680 --> 00:09:39.472 OK, so how are we going to think about, how 00:09:39.472 --> 00:09:41.472 does face perception develop? 00:09:41.472 --> 00:09:42.930 Well just to get started, I'm going 00:09:42.930 --> 00:09:50.658 to show you a very brief movie of a 72-hour-old monkey, 00:09:50.658 --> 00:09:51.910 and see what you think. 00:10:09.360 --> 00:10:09.860 He's sleepy. 00:10:20.180 --> 00:10:22.070 He's pretty interested in that face. 00:10:22.070 --> 00:10:22.760 And watch now. 00:10:29.547 --> 00:10:30.047 Hmm. 00:10:41.478 --> 00:10:45.450 [LAUGHS] Pretty cute, huh? 00:10:45.450 --> 00:10:46.325 So what do you think? 00:10:49.250 --> 00:10:51.590 What does this tell us about face perception? 00:10:51.590 --> 00:10:52.090 Yeah? 00:10:52.090 --> 00:10:53.882 AUDIENCE: Did they try just moving anything 00:10:53.882 --> 00:10:54.610 in front of him? 00:10:54.610 --> 00:10:56.020 NANCY KANWISHER: Good question. 00:10:56.020 --> 00:10:57.080 Good for you. 00:10:57.080 --> 00:10:58.090 Quily, is that right? 00:10:58.090 --> 00:10:58.882 AUDIENCE: "Quile-y" 00:10:58.882 --> 00:11:02.320 NANCY KANWISHER: "Quile-y", all right. 00:11:02.320 --> 00:11:05.703 Yes, so Quiley asked, did they try moving just anything 00:11:05.703 --> 00:11:06.370 in front of him? 00:11:06.370 --> 00:11:07.930 Absolutely the right question. 00:11:07.930 --> 00:11:10.150 So that monkey seems pretty interested in that face, 00:11:10.150 --> 00:11:11.920 but a face is a moving thing. 00:11:11.920 --> 00:11:15.340 Motion is very salient to young primates-- humans, and monkeys, 00:11:15.340 --> 00:11:17.800 and many others, absolutely. 00:11:17.800 --> 00:11:19.180 What else did you see in here? 00:11:21.820 --> 00:11:22.543 Yeah. 00:11:22.543 --> 00:11:25.740 AUDIENCE: It started imitating [INAUDIBLE].. 00:11:25.740 --> 00:11:27.120 NANCY KANWISHER: Yeah, kind of. 00:11:27.120 --> 00:11:29.400 I mean, the person-- 00:11:29.400 --> 00:11:32.340 the adult human there-- was moving their mouth open 00:11:32.340 --> 00:11:35.382 like this, and the monkey was doing something 00:11:35.382 --> 00:11:36.090 with their mouth. 00:11:36.090 --> 00:11:37.995 So what would that require? 00:11:41.030 --> 00:11:41.530 Sorry? 00:11:41.530 --> 00:11:43.340 AUDIENCE: I like, I have another. 00:11:43.340 --> 00:11:48.958 Also, was the monkey allowed to touch its face before this? 00:11:48.958 --> 00:11:50.500 NANCY KANWISHER: Yeah, good question. 00:11:50.500 --> 00:11:51.340 Good question. 00:11:51.340 --> 00:11:55.450 72 hours is damned early, but it's not zero experience, 00:11:55.450 --> 00:11:56.320 right? 00:11:56.320 --> 00:11:59.350 So who knows what they've managed to pick up that early. 00:11:59.350 --> 00:12:01.250 There are actually studies in humans, 00:12:01.250 --> 00:12:03.340 which I'm hoping Heather knows better than me. 00:12:03.340 --> 00:12:04.720 Those Andy Melzoff things. 00:12:04.720 --> 00:12:05.890 How young are those humans? 00:12:05.890 --> 00:12:08.532 Those are like first hour. 00:12:08.532 --> 00:12:10.135 AUDIENCE: Yeah, [INAUDIBLE]. 00:12:10.135 --> 00:12:11.510 NANCY KANWISHER: I think it's a-- 00:12:11.510 --> 00:12:12.718 AUDIENCE: [INAUDIBLE] 00:12:12.718 --> 00:12:14.260 NANCY KANWISHER: So there are studies 00:12:14.260 --> 00:12:16.300 in humans where you can show versions of that, 00:12:16.300 --> 00:12:19.132 with newborn infants copying-- 00:12:19.132 --> 00:12:21.340 the experimenter comes up and sticks their tongue out 00:12:21.340 --> 00:12:25.210 at the infant, and the infant does that back, kinda sorta. 00:12:25.210 --> 00:12:29.210 Certainly within the first two days, maybe even earlier, OK? 00:12:29.210 --> 00:12:31.090 OK, so it's very suggestive. 00:12:31.090 --> 00:12:33.700 It's tantalizing, but we need controlled conditions. 00:12:33.700 --> 00:12:37.210 It doesn't tell us everything we need to know. 00:12:37.210 --> 00:12:39.055 OK, so if we think about it, there 00:12:39.055 --> 00:12:44.020 are ends of the hypothesis space about how all of this could go. 00:12:44.020 --> 00:12:47.228 As Alana mentioned, everything is both genes and experience. 00:12:47.228 --> 00:12:49.270 That's true, but there are very, very importantly 00:12:49.270 --> 00:12:51.790 different ways in which genes and experience can 00:12:51.790 --> 00:12:57.730 act together-- some in which a big part of the heft of what 00:12:57.730 --> 00:12:59.425 the adult form has might be built in, 00:12:59.425 --> 00:13:01.300 and other stories where most of the structure 00:13:01.300 --> 00:13:02.360 comes from experience. 00:13:02.360 --> 00:13:04.318 So just because everything is both doesn't mean 00:13:04.318 --> 00:13:07.120 we shouldn't flesh out exactly what comes from what. 00:13:07.120 --> 00:13:11.020 So on one end of the spectrum, you 00:13:11.020 --> 00:13:14.440 might imagine that there's some very, very rudimentary 00:13:14.440 --> 00:13:19.330 precursor that has to be built in, plus a learning mechanism, 00:13:19.330 --> 00:13:20.350 OK? 00:13:20.350 --> 00:13:23.080 Or a bunch of rudimentary precursors, 00:13:23.080 --> 00:13:24.820 which are just there to get the system 00:13:24.820 --> 00:13:27.280 to learn in the right way, OK? 00:13:27.280 --> 00:13:29.590 And so we'll talk shortly about the idea 00:13:29.590 --> 00:13:33.340 that there might be some kind of innate template for faces 00:13:33.340 --> 00:13:36.490 that gets monkeys and humans to look at faces. 00:13:36.490 --> 00:13:38.920 And then, the idea is once you get them to look at a face, 00:13:38.920 --> 00:13:42.250 then experience can take over from there and do the rest. 00:13:42.250 --> 00:13:46.600 But you've got to get them to collect the right input. 00:13:46.600 --> 00:13:49.450 And there's lots of interesting computational work going on now 00:13:49.450 --> 00:13:53.680 where people are using various computational models to say, 00:13:53.680 --> 00:13:55.930 what do we have to build into, say, 00:13:55.930 --> 00:13:58.570 a convolutional neural network or some other kind 00:13:58.570 --> 00:14:02.650 of computational model to get it to do some complicated thing? 00:14:02.650 --> 00:14:06.160 I just came from a job talk the last hour-- really amazing 00:14:06.160 --> 00:14:08.440 talk-- where the guy is showing that if you build 00:14:08.440 --> 00:14:12.460 in, basically, curiosity early on in a network, 00:14:12.460 --> 00:14:15.610 you get much more general learners than if you 00:14:15.610 --> 00:14:20.890 build in a bunch of goals for a developing network to seek. 00:14:20.890 --> 00:14:23.530 anyway it's a very active area, and the paper 00:14:23.530 --> 00:14:25.570 that I just decided to assign to you guys, 00:14:25.570 --> 00:14:27.760 just kind of skim it and get the gist. 00:14:27.760 --> 00:14:30.290 The basic idea-- this is from Shimon Ullman, 00:14:30.290 --> 00:14:32.140 who is a very deep thinker in this field. 00:14:32.140 --> 00:14:36.130 And he argues that hands are very important in infants. 00:14:36.130 --> 00:14:40.065 Faces are important, but so are hands, because hands do stuff. 00:14:40.065 --> 00:14:41.440 And we're social primates, and we 00:14:41.440 --> 00:14:44.050 want to learn from other social primates like our parents. 00:14:44.050 --> 00:14:46.145 And watching their hands is extremely informative. 00:14:46.145 --> 00:14:47.770 Whatever they're doing with their hands 00:14:47.770 --> 00:14:49.840 is probably stuff we need to learn about. 00:14:49.840 --> 00:14:52.840 And further, we need to know where they're looking, right? 00:14:52.840 --> 00:14:54.295 So gaze perception. 00:14:54.295 --> 00:14:55.605 I think I did this demo before. 00:14:55.605 --> 00:14:57.730 If I'm talking to you guys, and I start doing that, 00:14:57.730 --> 00:15:00.147 it's really hard, even though you know I'm just faking you 00:15:00.147 --> 00:15:04.150 out, not to have your attention pulled over there, 00:15:04.150 --> 00:15:06.140 and infants need to learn that as well. 00:15:06.140 --> 00:15:09.070 So Shimon Ullman's basic idea is that you 00:15:09.070 --> 00:15:11.920 can start with an extremely rudimentary system, 00:15:11.920 --> 00:15:14.470 and all you have to build in is this idea that he 00:15:14.470 --> 00:15:15.850 calls "mover," right? 00:15:15.850 --> 00:15:18.970 So the idea is that if you look in a whole set of, say, YouTube 00:15:18.970 --> 00:15:22.030 videos, and you just look for patches of the image that 00:15:22.030 --> 00:15:23.800 are moving, that's no good. 00:15:23.800 --> 00:15:24.800 It won't be a hand. 00:15:24.800 --> 00:15:27.770 It might be a whole animal, or a face, or something else. 00:15:27.770 --> 00:15:30.220 But if you look in YouTube videos, 00:15:30.220 --> 00:15:33.370 a proxy for natural experience-- it's OK; it's not perfect, 00:15:33.370 --> 00:15:36.730 but it's something- you look for a patch of the image that 00:15:36.730 --> 00:15:41.230 moves over and then causes another previously-stationary 00:15:41.230 --> 00:15:43.270 image patch to move. 00:15:43.270 --> 00:15:46.660 That's what happens when we pick stuff up, OK? 00:15:46.660 --> 00:15:49.930 And so his idea is you can build in this extremely simple 00:15:49.930 --> 00:15:50.470 thing-- 00:15:50.470 --> 00:15:53.620 Mover, which is a very simple visual algorithm, 00:15:53.620 --> 00:15:56.540 can find image patches and move over and cause another image 00:15:56.540 --> 00:15:57.625 patch-- 00:15:57.625 --> 00:15:59.770 or then the two image patches move together. 00:15:59.770 --> 00:16:02.770 And Mover will enable you to identify hands in images 00:16:02.770 --> 00:16:03.400 pretty well. 00:16:03.400 --> 00:16:04.900 He looks in YouTube videos and shows 00:16:04.900 --> 00:16:06.970 that it's really good at picking out hands. 00:16:06.970 --> 00:16:09.760 And then, further, once you've picked out hands, 00:16:09.760 --> 00:16:11.710 that's a really important teaching signal 00:16:11.710 --> 00:16:13.300 in teaching you to read gaze. 00:16:13.300 --> 00:16:15.430 Because often, people look at their hands 00:16:15.430 --> 00:16:18.760 before they do things with them, yeah? 00:16:18.760 --> 00:16:21.940 So the idea is there's a very active ferment now 00:16:21.940 --> 00:16:23.570 in computational modeling saying, 00:16:23.570 --> 00:16:26.710 how can we start with just the most rudimentary, minimalist 00:16:26.710 --> 00:16:30.415 stuff that has to be built in, and then build on experience 00:16:30.415 --> 00:16:31.540 to get the rest from there? 00:16:31.540 --> 00:16:32.757 Is that idea clear? 00:16:32.757 --> 00:16:34.340 It's worth reading that paper, though. 00:16:34.340 --> 00:16:35.382 It's beautifully written. 00:16:35.382 --> 00:16:36.430 He's brilliant. 00:16:36.430 --> 00:16:38.740 OK, so that's one end of the spectrum. 00:16:38.740 --> 00:16:42.873 Nobody thinks that you learn absolutely everything 00:16:42.873 --> 00:16:43.540 from experience. 00:16:43.540 --> 00:16:44.830 You've got to build in something. 00:16:44.830 --> 00:16:46.955 Plus, we know all those neurons are there at birth. 00:16:46.955 --> 00:16:48.800 And so the idea is some version-- 00:16:48.800 --> 00:16:52.428 the minimalist nativist view says 00:16:52.428 --> 00:16:54.220 you build in a few very rudimentary things, 00:16:54.220 --> 00:16:56.200 and they're enough to bootstrap learning. 00:16:56.200 --> 00:17:00.052 OK, on the other end of the spectrum, you might think-- 00:17:00.052 --> 00:17:01.510 and many have proposed-- that we're 00:17:01.510 --> 00:17:04.390 born with a nearly adult-like system that 00:17:04.390 --> 00:17:07.900 only needs fine-tuning from experience, right? 00:17:07.900 --> 00:17:10.990 Nobody thinks that zero experience is necessary. 00:17:10.990 --> 00:17:14.750 That would be kind of crazy, or implausible. 00:17:14.750 --> 00:17:18.260 But on the other extreme, this view is that most of the stuff 00:17:18.260 --> 00:17:19.250 is built-in. 00:17:19.250 --> 00:17:21.260 OK, everybody get the theoretical space here 00:17:21.260 --> 00:17:22.910 that we're considering? 00:17:22.910 --> 00:17:26.339 OK, so what kind of data can constrain these questions? 00:17:26.339 --> 00:17:29.180 Well, one obvious question is, what is present at birth? 00:17:29.180 --> 00:17:30.440 What is the initial state-- 00:17:30.440 --> 00:17:33.740 or as close as we can get to it? 00:17:33.740 --> 00:17:36.440 Then we can ask, how does the system change over time 00:17:36.440 --> 00:17:38.240 from birth onward? 00:17:38.240 --> 00:17:41.090 And then we can ask, what are the causal roles of experience 00:17:41.090 --> 00:17:44.900 and biological maturation in that change after birth? 00:17:44.900 --> 00:17:46.848 So that's the whole set of questions 00:17:46.848 --> 00:17:48.890 we'd need to answer to understand how development 00:17:48.890 --> 00:17:49.910 works. 00:17:49.910 --> 00:17:52.520 And a very central-- if not the central-- challenge 00:17:52.520 --> 00:17:57.080 of development is that experience and maturation are 00:17:57.080 --> 00:18:01.040 deeply confounded as you look from birth onward, right? 00:18:01.040 --> 00:18:03.830 So five-year-olds are both more mature-- 00:18:03.830 --> 00:18:06.080 they've had more time for their biological systems 00:18:06.080 --> 00:18:08.750 to wire themselves up, including their bodies, and their brains, 00:18:08.750 --> 00:18:09.960 and the whole bit-- 00:18:09.960 --> 00:18:12.920 and maybe some of that is just on a maturation 00:18:12.920 --> 00:18:14.090 kind of autopilot. 00:18:14.090 --> 00:18:16.560 But they've also had a lot more experience. 00:18:16.560 --> 00:18:18.620 So one of the central challenges of development 00:18:18.620 --> 00:18:21.140 is trying to figure out how those later stages-- 00:18:21.140 --> 00:18:24.410 like two months old, one year old, 10 years old-- 00:18:24.410 --> 00:18:29.180 how those changes that happen between birth and those stages 00:18:29.180 --> 00:18:29.990 can-- 00:18:29.990 --> 00:18:33.310 how can we tease apart which of that came from just maturation 00:18:33.310 --> 00:18:34.910 and which came from experience? 00:18:34.910 --> 00:18:37.430 All right, OK. 00:18:37.430 --> 00:18:41.720 Importantly, things that happen well after birth 00:18:41.720 --> 00:18:46.660 need not be learned, right? 00:18:46.660 --> 00:18:48.190 So think about puberty. 00:18:48.190 --> 00:18:52.210 Puberty is going to happen around 10, 11, 12. 00:18:52.210 --> 00:18:54.850 And OK, you've got to eat and have 00:18:54.850 --> 00:18:56.630 some basic inputs to your system, 00:18:56.630 --> 00:18:58.660 but it's pretty much going to happen. 00:18:58.660 --> 00:19:01.510 It's not a product of what you were taught 00:19:01.510 --> 00:19:03.670 or the particular information that landed 00:19:03.670 --> 00:19:06.280 on your sensory receptors. 00:19:06.280 --> 00:19:08.590 I'm sure there's some obscure influences that I 00:19:08.590 --> 00:19:10.120 don't know about, but mostly, it's 00:19:10.120 --> 00:19:11.980 on a developmental autopilot. 00:19:11.980 --> 00:19:13.240 It's just going to happen. 00:19:13.240 --> 00:19:15.310 OK, so keep in mind-- this is really important-- 00:19:15.310 --> 00:19:17.350 that things that happen well after birth 00:19:17.350 --> 00:19:19.030 aren't necessarily learned. 00:19:19.030 --> 00:19:22.630 It might be just maturation that's continuing, right? 00:19:22.630 --> 00:19:26.740 OK, just as being 5 feet tall versus a foot and 1/2 tall 00:19:26.740 --> 00:19:27.940 isn't really learned. 00:19:27.940 --> 00:19:33.070 It's just a maturation program that unfolds. 00:19:33.070 --> 00:19:37.000 OK, so we can ask these three questions both behaviorally 00:19:37.000 --> 00:19:38.110 and naturally. 00:19:38.110 --> 00:19:40.450 And ultimately, we want them to tell the same story. 00:19:40.450 --> 00:19:43.150 When I said there's some chaos in this field right now, 00:19:43.150 --> 00:19:45.850 I mean that basically, they're not converging very well yet, 00:19:45.850 --> 00:19:47.770 but that's fun-- 00:19:47.770 --> 00:19:48.310 sort of. 00:19:48.310 --> 00:19:49.960 [LAUGHS] Sometimes it's aggravating, 00:19:49.960 --> 00:19:51.310 but mostly, it's fun. 00:19:51.310 --> 00:19:53.390 OK, so let's start with some behavioral data. 00:19:53.390 --> 00:19:54.970 So let's consider the initial state 00:19:54.970 --> 00:19:57.100 of face perception in newborns. 00:19:57.100 --> 00:20:01.060 OK, so we can ask, what kind of perceptual, face perceptual 00:20:01.060 --> 00:20:02.650 abilities are present in newborns? 00:20:02.650 --> 00:20:04.990 And we can ask whether they can detect a face-- that 00:20:04.990 --> 00:20:07.690 is, discriminate a face from a non-face, 00:20:07.690 --> 00:20:12.190 whether it's a body, or an object, or something else. 00:20:12.190 --> 00:20:14.500 We can ask about preferred attention to faces. 00:20:14.500 --> 00:20:16.510 Do they, do newborns want to look at faces 00:20:16.510 --> 00:20:18.610 more than non-faces? 00:20:18.610 --> 00:20:21.280 We can ask about the ability to recognize faces, 00:20:21.280 --> 00:20:25.150 to discriminate one face from another, OK? 00:20:25.150 --> 00:20:27.460 And we can ask about the ability to recognize faces 00:20:27.460 --> 00:20:28.695 across image changes. 00:20:28.695 --> 00:20:30.820 So we spent a lot of time in the first few lectures 00:20:30.820 --> 00:20:32.890 talking about the central problem of invariance 00:20:32.890 --> 00:20:33.880 in vision-- 00:20:33.880 --> 00:20:36.010 about, how do you know that this image that you're 00:20:36.010 --> 00:20:38.110 looking at here is the same person as that image, 00:20:38.110 --> 00:20:40.480 even though those are very different images? 00:20:40.480 --> 00:20:43.180 And actually, this image on your retina right 00:20:43.180 --> 00:20:46.810 now is more different than this image on your retina 00:20:46.810 --> 00:20:49.360 than if we got one of you and came up-- had you come up here 00:20:49.360 --> 00:20:50.920 and had you look forward. 00:20:50.920 --> 00:20:54.253 So the image changes that result from a change in orientation 00:20:54.253 --> 00:20:56.170 are greater than the image changes that result 00:20:56.170 --> 00:20:57.490 from a change in identity. 00:20:57.490 --> 00:20:59.410 So it's a big computational challenge. 00:20:59.410 --> 00:21:02.140 When is that solved? 00:21:02.140 --> 00:21:04.630 And then, there are these so-called signatures 00:21:04.630 --> 00:21:06.538 of face perception that we've talked 00:21:06.538 --> 00:21:08.830 about a little bit-- for example, the inversion effect. 00:21:08.830 --> 00:21:11.650 Recall the inversion effect is larger in magnitude 00:21:11.650 --> 00:21:12.820 for faces than non-faces. 00:21:12.820 --> 00:21:15.940 So we can ask when those things develop. 00:21:15.940 --> 00:21:17.740 OK, so let's start with face detection 00:21:17.740 --> 00:21:20.620 and preferred attention to faces. 00:21:20.620 --> 00:21:22.990 Well, so classic studies from the early 00:21:22.990 --> 00:21:26.110 '90s, and actually, some of them going back to the '70s, 00:21:26.110 --> 00:21:27.910 did the following very low-tech thing-- 00:21:27.910 --> 00:21:30.380 a low-tech drawing of a low-tech experiment. 00:21:30.380 --> 00:21:31.870 You take a newborn infant. 00:21:31.870 --> 00:21:34.900 In this case, they're less than an hour old, right? 00:21:34.900 --> 00:21:37.210 You've got to set up in maternity wards. 00:21:37.210 --> 00:21:39.850 You want the data, that's what you do. 00:21:39.850 --> 00:21:42.740 Of course, you have to ask the parents and all of that. 00:21:42.740 --> 00:21:44.800 But then, you take this infant and you sit them 00:21:44.800 --> 00:21:47.770 on a person's lap with a video camera overhead, 00:21:47.770 --> 00:21:52.540 and you move different objects over the infant's head, OK? 00:21:52.540 --> 00:21:55.900 And the different objects that were moved, in this case, 00:21:55.900 --> 00:21:58.330 were patterns that were drawn on this paddle that's 00:21:58.330 --> 00:22:00.220 moved over the infant's head. 00:22:00.220 --> 00:22:03.730 And the pattern could be a schematic face like that, 00:22:03.730 --> 00:22:06.430 a scrambled schematic face like that, 00:22:06.430 --> 00:22:09.850 and a blank with nothing in it. 00:22:09.850 --> 00:22:12.040 And what you measure is, how far does the infant 00:22:12.040 --> 00:22:15.940 turn their head or their eyes following that paddle as you 00:22:15.940 --> 00:22:17.350 move it over them. 00:22:17.350 --> 00:22:19.480 OK, nice low-tech measure. 00:22:19.480 --> 00:22:23.410 And what you find is they turn their heads and their eyes 00:22:23.410 --> 00:22:26.440 farther when it's an actual schematic face than when it's 00:22:26.440 --> 00:22:32.750 a scrambled schematic face or a blank, within an hour of birth. 00:22:32.750 --> 00:22:35.650 Then you can still say, well, their parents probably 00:22:35.650 --> 00:22:38.020 smiled at them quickly before they were snatched away 00:22:38.020 --> 00:22:42.070 to do the experiment, so they had some face experience, 00:22:42.070 --> 00:22:43.880 but boy, not a whole lot. 00:22:43.880 --> 00:22:46.160 And this is a very abstract face here. 00:22:46.160 --> 00:22:49.480 So this has long been taken as one of the key bits of evidence 00:22:49.480 --> 00:22:55.540 that something seems likely to be innate about faces, OK? 00:22:55.540 --> 00:23:00.640 But now, what needs to be innate for that? 00:23:00.640 --> 00:23:03.902 And it's a bizarre thing, where this happens in the first two 00:23:03.902 --> 00:23:05.110 months of life and goes away. 00:23:05.110 --> 00:23:06.310 And there's a lot of consideration 00:23:06.310 --> 00:23:07.270 of what that means. 00:23:07.270 --> 00:23:09.400 Maybe the first two months is enough to bootstrap 00:23:09.400 --> 00:23:10.983 learning in the way I was just talking 00:23:10.983 --> 00:23:14.860 about-- bootstrapping, getting attention to the right places. 00:23:14.860 --> 00:23:17.470 But there's also a huge literature on this phenomenon 00:23:17.470 --> 00:23:19.870 where there's a big debate about exactly how 00:23:19.870 --> 00:23:21.910 simple those cues need to be. 00:23:21.910 --> 00:23:25.120 So people have done many variations of this 00:23:25.120 --> 00:23:29.440 and one dominant story is that all you need 00:23:29.440 --> 00:23:33.820 is a pattern that has more stuff on the top than on the bottom, 00:23:33.820 --> 00:23:34.600 OK? 00:23:34.600 --> 00:23:36.280 And that's enough that infants will 00:23:36.280 --> 00:23:39.080 follow this more than that. 00:23:39.080 --> 00:23:41.710 And the idea is that in the visual environment 00:23:41.710 --> 00:23:45.920 of an infant, that's sufficient to pick out faces. 00:23:45.920 --> 00:23:48.137 So there's been pushback against this view as well. 00:23:48.137 --> 00:23:50.220 It's probably a little more complicated than that. 00:23:50.220 --> 00:23:53.060 We won't go down the rabbit hole of all those details, 00:23:53.060 --> 00:23:56.090 but whatever it is, it's pretty simple. 00:23:56.090 --> 00:23:58.580 So this is another example of what I was mentioning before 00:23:58.580 --> 00:23:59.750 with the Ullman case. 00:23:59.750 --> 00:24:02.930 This is a case where it may be possible to build 00:24:02.930 --> 00:24:04.880 in something pretty basic-- 00:24:04.880 --> 00:24:06.380 a pretty basic template-- and then 00:24:06.380 --> 00:24:08.210 let learning take it from there. 00:24:08.210 --> 00:24:08.820 Make sense? 00:24:08.820 --> 00:24:10.320 If the infants are looking at faces, 00:24:10.320 --> 00:24:14.030 then they can use some kind of synaptic plasticity, whatever, 00:24:14.030 --> 00:24:16.370 and learn from their experience to discriminate 00:24:16.370 --> 00:24:17.900 one face from another. 00:24:17.900 --> 00:24:21.800 OK, so these things are present within a day or two. 00:24:21.800 --> 00:24:24.758 What about discrimination of individual identity? 00:24:24.758 --> 00:24:26.300 First problem, how are we going to be 00:24:26.300 --> 00:24:29.540 able to tell what a newborn can see? 00:24:29.540 --> 00:24:31.250 And so I didn't want you guys to be 00:24:31.250 --> 00:24:33.350 to thrown by this method in the last assignment, 00:24:33.350 --> 00:24:37.278 so I told you where there's a version of the explanation I'm 00:24:37.278 --> 00:24:38.070 just going to give. 00:24:38.070 --> 00:24:39.945 So if you already watched that, my apologies. 00:24:39.945 --> 00:24:42.240 You can read your email for a minute. 00:24:42.240 --> 00:24:45.920 So the classic experiment-- 00:24:45.920 --> 00:24:48.500 a classic experiment-- that enabled 00:24:48.500 --> 00:24:52.910 us to really ask how a newborn, non-verbal infant, what 00:24:52.910 --> 00:24:56.300 they see in the world, is done by Kellman and Spelke. 00:24:56.300 --> 00:24:58.460 Liz Spelke up at Harvard was at the forefront 00:24:58.460 --> 00:25:00.830 of getting this method to really tell us 00:25:00.830 --> 00:25:03.860 a huge great deal about what infants see and understand 00:25:03.860 --> 00:25:04.535 about the world. 00:25:04.535 --> 00:25:06.410 And this method that I'm about to show to you 00:25:06.410 --> 00:25:08.990 has been the basis of what's sometimes called "The Infancy 00:25:08.990 --> 00:25:12.140 Revolution," which is basically the insight that, actually, 00:25:12.140 --> 00:25:14.420 infants know a lot. 00:25:14.420 --> 00:25:16.800 Their perceptual systems are really sophisticated. 00:25:16.800 --> 00:25:17.930 They know about physics. 00:25:17.930 --> 00:25:19.760 They know all kinds of social stuff. 00:25:19.760 --> 00:25:22.070 Within a few months of life, they know a lot. 00:25:22.070 --> 00:25:24.860 And that's been a radical change in our understanding 00:25:24.860 --> 00:25:27.420 of development based on just behavioral work. 00:25:27.420 --> 00:25:29.360 So here's the method. 00:25:29.360 --> 00:25:31.430 OK, so what Spelke did-- 00:25:31.430 --> 00:25:33.140 I always forget to bring the demo. 00:25:33.140 --> 00:25:34.145 Hang on one moment. 00:25:36.950 --> 00:25:38.810 We don't need much. 00:25:38.810 --> 00:25:43.133 OK, so she showed infants stuff like this, OK? 00:25:43.133 --> 00:25:44.300 The two hands are not there. 00:25:44.300 --> 00:25:47.600 You just arranged to see this, OK? 00:25:47.600 --> 00:25:49.490 So even if you hadn't seen me, imagine 00:25:49.490 --> 00:25:52.190 if you hadn't seen me pick up the phone and the pen, 00:25:52.190 --> 00:25:54.500 and you didn't already know what they were, 00:25:54.500 --> 00:25:56.330 and you're seeing this, OK? 00:25:56.330 --> 00:25:59.450 That's what they see, OK? 00:25:59.450 --> 00:26:01.880 So now, the question is, when infants see that, 00:26:01.880 --> 00:26:04.280 do they think that that's this-- 00:26:04.280 --> 00:26:06.980 thing behind a rectangle-- 00:26:06.980 --> 00:26:09.260 or do they think it's two separate bits moving 00:26:09.260 --> 00:26:10.400 behind the rectangle? 00:26:10.400 --> 00:26:12.740 It could be two separate bits moving together, right? 00:26:12.740 --> 00:26:14.390 Everybody get the question? 00:26:14.390 --> 00:26:16.730 OK, so how would we know what the infants thought 00:26:16.730 --> 00:26:18.410 was back there? 00:26:18.410 --> 00:26:22.880 OK, well, we use what's known as habituation of looking time. 00:26:22.880 --> 00:26:24.860 Again, you sit the infant on a parent's lap, 00:26:24.860 --> 00:26:26.480 and you show them stuff, and you just 00:26:26.480 --> 00:26:28.280 measure how long they look. 00:26:28.280 --> 00:26:31.880 It's magnificently low-tech but really profound. 00:26:31.880 --> 00:26:34.310 OK, so what we're going to show here 00:26:34.310 --> 00:26:37.760 is how long the infant looks on each trial as a function 00:26:37.760 --> 00:26:40.860 of how many times you do it. 00:26:40.860 --> 00:26:43.100 So you show the infant this the first time, 00:26:43.100 --> 00:26:44.630 and they look for 40 seconds. 00:26:44.630 --> 00:26:45.650 That's a long time. 00:26:45.650 --> 00:26:49.410 You show them again, they look for 35 seconds, and so forth. 00:26:49.410 --> 00:26:53.570 And by the fifth or sixth time, the infant is bored. 00:26:53.570 --> 00:26:57.530 Like been there, done that, bored, right? 00:26:57.530 --> 00:26:59.210 OK, now they're bored. 00:26:59.210 --> 00:27:03.540 Now we have a moment to say, OK, what did you think it was? 00:27:03.540 --> 00:27:08.630 And so now, what you can ask is, what do they think-- 00:27:08.630 --> 00:27:11.160 you then show them either this or this, 00:27:11.160 --> 00:27:14.570 and you ask them which of those they're bored to, right? 00:27:14.570 --> 00:27:17.390 So the idea is if, when looking at this, 00:27:17.390 --> 00:27:19.190 they thought there was a continuous line 00:27:19.190 --> 00:27:22.880 behind the occluder, then they should be more bored by this. 00:27:22.880 --> 00:27:25.683 But if they thought that was two separate pieces, then 00:27:25.683 --> 00:27:27.100 they should be more bored by that. 00:27:27.100 --> 00:27:28.298 Does that makes sense? 00:27:28.298 --> 00:27:30.590 Because it's the same thing they're already bored with. 00:27:30.590 --> 00:27:32.007 I mean, it's not exactly the same. 00:27:32.007 --> 00:27:33.620 The occluder isn't there, right? 00:27:33.620 --> 00:27:35.180 But it's more similar. 00:27:35.180 --> 00:27:36.950 OK, so here's the data. 00:27:36.950 --> 00:27:38.040 Here's what they find. 00:27:38.040 --> 00:27:39.390 So what does that mean? 00:27:39.390 --> 00:27:41.742 What do the infants see when you show them this? 00:27:41.742 --> 00:27:42.950 It's right there in the data. 00:27:42.950 --> 00:27:45.260 Look at the first test trial here. 00:27:45.260 --> 00:27:46.880 This is the first test trial, when 00:27:46.880 --> 00:27:52.190 you show the complete line or the broken line. 00:27:52.190 --> 00:27:54.410 What do they see here? 00:27:54.410 --> 00:27:56.090 Yeah, they saw the complete one. 00:27:56.090 --> 00:27:59.000 That's why, when you present the complete one again, 00:27:59.000 --> 00:28:00.440 they're still bored-- 00:28:00.440 --> 00:28:02.000 already saw that. 00:28:02.000 --> 00:28:03.870 Make sense? 00:28:03.870 --> 00:28:04.850 So isn't that awesome? 00:28:04.850 --> 00:28:07.430 It's so low-tech and so simple, but this 00:28:07.430 --> 00:28:10.070 is how you can ask an infant, what do you see? 00:28:10.070 --> 00:28:10.832 Yeah? 00:28:10.832 --> 00:28:13.550 AUDIENCE: Why does it switch positions in the second trial? 00:28:13.550 --> 00:28:15.800 NANCY KANWISHER: You know, frankly, I never understand 00:28:15.800 --> 00:28:18.080 why infant and development people do 00:28:18.080 --> 00:28:19.330 a second and third trial. 00:28:19.330 --> 00:28:21.303 Seems to me by this point, the jig is up. 00:28:21.303 --> 00:28:23.720 I think it's just because it's hard to get enough infants, 00:28:23.720 --> 00:28:25.070 and you need more data, and so they 00:28:25.070 --> 00:28:26.330 do a second and third trial. 00:28:26.330 --> 00:28:28.580 But to me, that's the diagnostic one. 00:28:28.580 --> 00:28:30.710 And that's probably not a significant switch, 00:28:30.710 --> 00:28:32.820 but whatever's going on out there is obviously 00:28:32.820 --> 00:28:34.070 much less important than this. 00:28:34.070 --> 00:28:35.870 Heather, do you have a better answer than that? 00:28:35.870 --> 00:28:37.287 Why do they do those other trials? 00:28:37.287 --> 00:28:40.980 They always do, and it just seems like, what? 00:28:40.980 --> 00:28:41.480 [LAUGHS] 00:28:41.480 --> 00:28:42.438 AUDIENCE: I don't know. 00:28:42.438 --> 00:28:44.480 NANCY KANWISHER: Yeah, I don't either. 00:28:44.480 --> 00:28:45.802 AUDIENCE: [INAUDIBLE]? 00:28:45.802 --> 00:28:47.760 NANCY KANWISHER: Oh, you do it every which way, 00:28:47.760 --> 00:28:48.930 but you do it pretty fast. 00:28:48.930 --> 00:28:51.420 They get bored, and you don't want to wait half an hour 00:28:51.420 --> 00:28:52.470 and come back, right? 00:28:52.470 --> 00:28:53.553 I mean, you could do that. 00:28:53.553 --> 00:28:56.130 Then that would be a memory question, right? 00:28:56.130 --> 00:28:57.900 Yeah, Jimmy. 00:28:57.900 --> 00:29:00.315 AUDIENCE: Just curious, is this conserved 00:29:00.315 --> 00:29:03.640 between [INAUDIBLE] do they all see complete lines, where 00:29:03.640 --> 00:29:04.140 [INAUDIBLE]? 00:29:04.140 --> 00:29:05.220 NANCY KANWISHER: It's pretty robust. 00:29:05.220 --> 00:29:06.887 Well, OK, so first of all, these methods 00:29:06.887 --> 00:29:09.060 are awesome, that you can learn these deep things 00:29:09.060 --> 00:29:11.220 about perception in infants. 00:29:11.220 --> 00:29:12.720 But these data are noisy as hell. 00:29:12.720 --> 00:29:14.220 There's no error bars on this plot, 00:29:14.220 --> 00:29:16.678 but I bet if there were, you'd have to run a lot of infants 00:29:16.678 --> 00:29:18.810 to get to the point where you reach significance. 00:29:18.810 --> 00:29:21.270 Because a lot of times, the infants will just throw up, 00:29:21.270 --> 00:29:24.160 or they'll just do what-- they do all kinds of random things. 00:29:24.160 --> 00:29:26.820 So the data are extremely noisy, and it's very hard 00:29:26.820 --> 00:29:28.210 to get enough data with an infant 00:29:28.210 --> 00:29:30.210 to say anything about the difference between one 00:29:30.210 --> 00:29:31.380 infant and another. 00:29:31.380 --> 00:29:34.230 By the way, there's a very exciting development going on 00:29:34.230 --> 00:29:36.000 in this department right now, where 00:29:36.000 --> 00:29:38.700 Kim Scott, who's a former grad student of this department, 00:29:38.700 --> 00:29:40.950 has figured out how to do looking time experiments 00:29:40.950 --> 00:29:43.560 like this online, OK? 00:29:43.560 --> 00:29:45.960 And that's hugely important, because the number one 00:29:45.960 --> 00:29:48.300 bottleneck in this kind of developmental research 00:29:48.300 --> 00:29:51.330 has been finding enough infants, or getting 00:29:51.330 --> 00:29:52.810 enough data per infant. 00:29:52.810 --> 00:29:55.350 And so I think that she's going to just crack it wide open. 00:29:55.350 --> 00:29:55.850 Talia? 00:29:55.850 --> 00:29:58.590 AUDIENCE: I guess I'm a little bit confused 00:29:58.590 --> 00:30:03.270 how we know what the infant really saw based on how long it 00:30:03.270 --> 00:30:05.670 looked at something. 00:30:05.670 --> 00:30:10.830 Could it be that maybe they look at like-- 00:30:10.830 --> 00:30:13.080 maybe they look at the broken sticks longer, 00:30:13.080 --> 00:30:15.460 because it's like what they thought was behind it, 00:30:15.460 --> 00:30:18.030 so they're now excited that they get to see what's-- 00:30:18.030 --> 00:30:20.730 NANCY KANWISHER: Maybe, but then, why would you get this? 00:30:20.730 --> 00:30:24.030 So we know from this that the more familiar it looks, 00:30:24.030 --> 00:30:26.130 the less time they look. 00:30:26.130 --> 00:30:27.840 So you would have to come up with-- yeah, 00:30:27.840 --> 00:30:29.170 there's wiggle room in these data, 00:30:29.170 --> 00:30:30.660 but you'd have to come-- your account would have 00:30:30.660 --> 00:30:32.520 to say, why would they look less, and less, 00:30:32.520 --> 00:30:35.640 and less long when we repeat the exact same thing, right? 00:30:35.640 --> 00:30:38.695 And you could tell a story like, OK, it's 00:30:38.695 --> 00:30:41.070 a little bit different, because the occluder isn't there. 00:30:41.070 --> 00:30:42.300 But it's a little bit the same, and that's 00:30:42.300 --> 00:30:43.175 kind of edgy and fun. 00:30:43.175 --> 00:30:45.570 Or you could tell another story, but I 00:30:45.570 --> 00:30:47.490 think the bulk of the developmental literature 00:30:47.490 --> 00:30:49.410 shows that when you do this kind of stuff, 00:30:49.410 --> 00:30:51.915 it's a change that makes infants look more. 00:30:51.915 --> 00:30:54.540 I'm going to go on unless there are questions of clarification, 00:30:54.540 --> 00:30:56.460 just because there's so much other cool stuff. 00:31:00.120 --> 00:31:02.760 OK, so how can we use this to study face recognition? 00:31:02.760 --> 00:31:05.130 That was just a sidebar on the method. 00:31:05.130 --> 00:31:07.200 OK, so there's a lab in Italy where 00:31:07.200 --> 00:31:10.230 they have an infant psychology lab next to a maternity ward, 00:31:10.230 --> 00:31:13.470 and they've been doing all these awesome studies. 00:31:13.470 --> 00:31:16.475 OK, and they test 1-3-day-old infants. 00:31:16.475 --> 00:31:17.850 And so one of the things they did 00:31:17.850 --> 00:31:21.323 is show infants, just like the paradigm I just showed you. 00:31:21.323 --> 00:31:23.490 They show the infant the same face again, and again, 00:31:23.490 --> 00:31:24.240 and again. 00:31:24.240 --> 00:31:26.460 That's the habituation phase. 00:31:26.460 --> 00:31:28.950 And then, this is a slightly different one. 00:31:28.950 --> 00:31:31.615 You give them a choice of whether they-- 00:31:31.615 --> 00:31:33.240 actually, you don't give them a choice. 00:31:33.240 --> 00:31:34.110 I take it back. 00:31:34.110 --> 00:31:37.200 Yeah, you show this condition or that condition, 00:31:37.200 --> 00:31:39.720 and you see how long they look at each 00:31:39.720 --> 00:31:41.040 across different infants. 00:31:41.040 --> 00:31:43.620 And so this is the same person from a different viewpoint. 00:31:43.620 --> 00:31:46.140 Actually, pretty subtle, as we discussed with the Jenkins 00:31:46.140 --> 00:31:47.640 study way back. 00:31:47.640 --> 00:31:50.130 And that's a different person from that viewpoint. 00:31:50.130 --> 00:31:53.640 And what they found is that-- it's hard to see, 00:31:53.640 --> 00:31:55.740 but a very low P level means that there's 00:31:55.740 --> 00:31:57.240 a significant difference in how much 00:31:57.240 --> 00:32:00.250 the infants looked at those two. 00:32:00.250 --> 00:32:02.070 So that's pretty amazing. 00:32:02.070 --> 00:32:06.570 1-3-day-old infants can apparently recognize 00:32:06.570 --> 00:32:10.710 the identity of a face, a novel individual they don't already 00:32:10.710 --> 00:32:14.850 know, with similar-looking faces, without hair, 00:32:14.850 --> 00:32:16.650 and across view changes. 00:32:16.650 --> 00:32:18.360 Wow, right? 00:32:18.360 --> 00:32:21.313 So that's pretty impressive. 00:32:21.313 --> 00:32:23.730 OK, and so then, they've done all kinds of other variants. 00:32:23.730 --> 00:32:26.420 If you have them rotate all the way from front profile, 00:32:26.420 --> 00:32:28.310 there's no longer a significant difference. 00:32:28.310 --> 00:32:30.435 Infants can't do that. 00:32:30.435 --> 00:32:32.310 And then they do all kinds of other variants. 00:32:32.310 --> 00:32:34.512 If you show them the same individual and then 00:32:34.512 --> 00:32:36.470 habituate to that, they can tell the difference 00:32:36.470 --> 00:32:37.310 between viewpoint. 00:32:37.310 --> 00:32:39.542 That's the same, and that's different, 00:32:39.542 --> 00:32:41.000 even though it's the same identity. 00:32:41.000 --> 00:32:42.650 So you can use this to test what they 00:32:42.650 --> 00:32:45.510 think is same or different, which is a deep question 00:32:45.510 --> 00:32:46.010 to ask. 00:32:46.010 --> 00:32:48.630 If you're interested in representations and cognition, 00:32:48.630 --> 00:32:51.680 the question of what an infant, or an animal, 00:32:51.680 --> 00:32:54.230 or a bunch of neurons thinks is the same or different 00:32:54.230 --> 00:32:56.840 is the essence of characterizing what it represents. 00:32:56.840 --> 00:32:57.680 Yeah, Quiley? 00:32:57.680 --> 00:33:01.385 AUDIENCE: [INAUDIBLE] the rotated face [INAUDIBLE]?? 00:33:01.385 --> 00:33:02.510 NANCY KANWISHER: Down here? 00:33:02.510 --> 00:33:03.290 Yeah. 00:33:03.290 --> 00:33:04.070 Yeah, they do. 00:33:04.070 --> 00:33:06.800 So here, basically, it's either identical, 00:33:06.800 --> 00:33:08.670 or it's different in some respect. 00:33:08.670 --> 00:33:13.940 So given a choice, when it's rotated anyway, 00:33:13.940 --> 00:33:16.310 the familiar one is more similar. 00:33:16.310 --> 00:33:18.980 But down here, this one is more similar in viewpoint. 00:33:18.980 --> 00:33:20.210 Yeah? 00:33:20.210 --> 00:33:22.850 AUDIENCE: And these are not like the [INAUDIBLE] 00:33:22.850 --> 00:33:26.338 in such [INAUDIBLE] the student, the [INAUDIBLE] 00:33:26.338 --> 00:33:27.880 NANCY KANWISHER: Sorry, say it again? 00:33:27.880 --> 00:33:28.630 They're not like-- 00:33:28.630 --> 00:33:31.285 AUDIENCE: The children have seen faces before this. 00:33:31.285 --> 00:33:33.160 NANCY KANWISHER: Well, as little as possible. 00:33:33.160 --> 00:33:35.960 As I say, I mean, they've seen some, but not very many, 00:33:35.960 --> 00:33:38.650 and they haven't seen these faces. 00:33:38.650 --> 00:33:42.160 So when you're trying to get those innateness questions, 00:33:42.160 --> 00:33:43.870 you go as close to birth as you can, 00:33:43.870 --> 00:33:46.240 but you can't usually go into the very moment 00:33:46.240 --> 00:33:47.260 of birth itself, right? 00:33:47.260 --> 00:33:49.270 And so there's usually some experience, 00:33:49.270 --> 00:33:51.310 and it's a challenge, but this is pretty early. 00:33:51.310 --> 00:33:52.270 Yeah? 00:33:52.270 --> 00:33:55.850 AUDIENCE: So couldn't that just meant that the face perception 00:33:55.850 --> 00:33:57.240 network is just like-- 00:33:57.240 --> 00:34:00.100 it develops really quickly, right after [INAUDIBLE].. 00:34:00.100 --> 00:34:01.600 NANCY KANWISHER: It could, it could. 00:34:01.600 --> 00:34:04.480 Based on these data alone, it could. 00:34:04.480 --> 00:34:05.950 That's considered kind of unlikely, 00:34:05.950 --> 00:34:08.440 but I agree that that's consistent with these data. 00:34:08.440 --> 00:34:10.719 In the first two days of life, the whole thing 00:34:10.719 --> 00:34:11.830 wires itself up. 00:34:11.830 --> 00:34:14.290 That's be pretty unusual. 00:34:14.290 --> 00:34:17.727 It's not really consistent with those samples of neurons 00:34:17.727 --> 00:34:19.810 that people have looked at elsewhere in the brain, 00:34:19.810 --> 00:34:22.090 but maybe there's a special little circuit that just 00:34:22.090 --> 00:34:23.659 wires itself up really fast. 00:34:23.659 --> 00:34:27.139 So not likely, but possible, OK? 00:34:27.139 --> 00:34:32.090 All right, now, you might say, well, maybe there's 00:34:32.090 --> 00:34:34.699 some kind of simple visual features 00:34:34.699 --> 00:34:37.628 that are short of an actual face representation here. 00:34:37.628 --> 00:34:39.920 This doesn't show us that this is something about faces 00:34:39.920 --> 00:34:42.500 per se, even though it can generalize across viewpoints. 00:34:42.500 --> 00:34:46.670 So it's not just pixel intensity, right? 00:34:46.670 --> 00:34:48.620 So what is the classic way we asked 00:34:48.620 --> 00:34:51.050 this question in face perception, where we ask, 00:34:51.050 --> 00:34:53.420 is this really something about faces, or is it 00:34:53.420 --> 00:34:56.040 something about the low-level perceptual properties 00:34:56.040 --> 00:34:56.540 of the face? 00:34:59.670 --> 00:35:00.920 AUDIENCE: Turn it upside down? 00:35:00.920 --> 00:35:03.500 NANCY KANWISHER: Yeah, turn it upside down. 00:35:03.500 --> 00:35:08.370 God's gift to the face researcher, right? 00:35:08.370 --> 00:35:11.990 So-- oh, I guess that was not on this slide. 00:35:11.990 --> 00:35:12.710 OK, right? 00:35:12.710 --> 00:35:14.840 OK, so now, in the next experiment, 00:35:14.840 --> 00:35:18.560 they present whole faces, or just the internal features 00:35:18.560 --> 00:35:22.980 without hair, or just the external features without hair. 00:35:22.980 --> 00:35:25.963 So the infants can do that at the top. 00:35:25.963 --> 00:35:27.380 They know those two are different. 00:35:27.380 --> 00:35:29.463 They can do this here, and they can do that there. 00:35:29.463 --> 00:35:30.680 OK, not too shocking yet. 00:35:30.680 --> 00:35:33.950 Just tells you any of those cues can support performance. 00:35:33.950 --> 00:35:39.110 But now, we can ask, is that just pattern-matching? 00:35:39.110 --> 00:35:39.950 No, it's not. 00:35:39.950 --> 00:35:41.630 Because when you turn them upside down, 00:35:41.630 --> 00:35:45.290 you find that only-- 00:35:45.290 --> 00:35:49.280 let's see, it's only performance in this case that 00:35:49.280 --> 00:35:51.380 suffers when you turn them upside-down, 00:35:51.380 --> 00:35:54.680 not this case or that case. 00:35:54.680 --> 00:35:57.410 OK, so that shows that there are a variety of cues here that 00:35:57.410 --> 00:36:00.200 infants could be using, but when you show them just the internal 00:36:00.200 --> 00:36:03.560 features-- the actual face proper-- 00:36:03.560 --> 00:36:05.930 that part, the ability to do this discrimination, 00:36:05.930 --> 00:36:08.060 goes away when you turn it upside down. 00:36:08.060 --> 00:36:11.600 So that part, at least, seems to be at least somewhat 00:36:11.600 --> 00:36:13.910 face-specific, or has the signature 00:36:13.910 --> 00:36:15.920 of face-specific processing. 00:36:15.920 --> 00:36:17.690 Make sense? 00:36:17.690 --> 00:36:20.840 OK, I mean, as a pattern, it'd be just as 00:36:20.840 --> 00:36:22.490 easy to recognize this upside-down 00:36:22.490 --> 00:36:24.530 and distinguish it from that upside-down, 00:36:24.530 --> 00:36:26.780 if it was just the pixels you were registering. 00:36:26.780 --> 00:36:28.640 But if you were doing face processing that's 00:36:28.640 --> 00:36:30.182 something like adult face processing, 00:36:30.182 --> 00:36:32.480 you'd expect that inversion effect. 00:36:32.480 --> 00:36:37.010 OK, all right, so where are we? 00:36:37.010 --> 00:36:40.130 And I should just say, even this is actively debated. 00:36:40.130 --> 00:36:43.580 In fact, the author of this study 00:36:43.580 --> 00:36:45.530 considers this not to be evidence 00:36:45.530 --> 00:36:48.020 that that processing is face-specific. 00:36:48.020 --> 00:36:50.690 I think she's got some of the strongest evidence ever, 00:36:50.690 --> 00:36:52.350 but she's got some counterargument 00:36:52.350 --> 00:36:54.350 about how in the inverted faces, they don't look 00:36:54.350 --> 00:36:55.880 as long in the situation phase. 00:36:55.880 --> 00:36:58.250 And so it's like I'm telling you these cool methods, 00:36:58.250 --> 00:37:01.340 but boy, every one of them can be fought over. 00:37:01.340 --> 00:37:03.530 OK, so where are? 00:37:03.530 --> 00:37:05.060 We've just shown that discrimination 00:37:05.060 --> 00:37:08.450 of individual identity is present in very young newborns, 00:37:08.450 --> 00:37:12.110 recognition across viewpoints, and inversion effects 00:37:12.110 --> 00:37:14.960 are all present within the first few days of life. 00:37:14.960 --> 00:37:18.890 OK, so newborns have very impressive face perception 00:37:18.890 --> 00:37:21.980 abilities, and that's particularly surprising 00:37:21.980 --> 00:37:24.690 given that their acuity is terrible, right? 00:37:24.690 --> 00:37:28.280 the vision is really blurry for young infants, 00:37:28.280 --> 00:37:30.750 so it's amazing that they can do these things. 00:37:30.750 --> 00:37:33.740 But now, there's room for quibbling about whether this is 00:37:33.740 --> 00:37:36.320 really a face-specific system. 00:37:36.320 --> 00:37:38.270 So the inversion effect is suggestive, 00:37:38.270 --> 00:37:40.940 but they haven't totally nailed the case about what's 00:37:40.940 --> 00:37:42.200 being tapped into here. 00:37:42.200 --> 00:37:44.480 Is it really face perception per se-- 00:37:44.480 --> 00:37:46.160 something specific to face perception-- 00:37:46.160 --> 00:37:50.420 or is it some more generic kind of object perception? 00:37:50.420 --> 00:37:54.350 OK, and further, we want to know what happens after that. 00:37:54.350 --> 00:37:57.985 OK, so you don't need to memorize this table. 00:37:57.985 --> 00:38:00.110 I'm just going to make a few simple points with it. 00:38:00.110 --> 00:38:02.030 There are lots and lots of studies 00:38:02.030 --> 00:38:05.030 where people have tested behaviorally all kinds 00:38:05.030 --> 00:38:07.370 of different aspects of face perception, 00:38:07.370 --> 00:38:09.950 and the basic story is that by age four, 00:38:09.950 --> 00:38:12.290 you see the little smiley face means 00:38:12.290 --> 00:38:16.730 that this adult-like property of the face perception system 00:38:16.730 --> 00:38:18.740 is present by age four. 00:38:18.740 --> 00:38:21.830 So all of those signatures of face perception 00:38:21.830 --> 00:38:25.580 that are present in adults are present by age four, OK? 00:38:25.580 --> 00:38:29.600 And in fact, much of the action is much before that. 00:38:29.600 --> 00:38:31.700 You can see that all of these things 00:38:31.700 --> 00:38:34.280 are present at the earliest age they've ever been tested. 00:38:34.280 --> 00:38:37.520 The little square means nobody's tested it at that age. 00:38:37.520 --> 00:38:43.220 So all this stuff is developing very fast, right? 00:38:43.220 --> 00:38:47.067 OK, one particularly important thing 00:38:47.067 --> 00:38:48.650 here that you read about a little bit, 00:38:48.650 --> 00:38:51.150 but that I want to take a moment to make sure you understand 00:38:51.150 --> 00:38:52.880 because it's so interesting and cool, 00:38:52.880 --> 00:38:55.700 is the phenomenon of perceptual narrowing, OK? 00:38:55.700 --> 00:38:57.260 And this happens in face perception, 00:38:57.260 --> 00:39:00.710 and it happens in phoneme perception in speech. 00:39:00.710 --> 00:39:02.550 And I'm going to do a demo here. 00:39:02.550 --> 00:39:04.527 So I'm going to show you a monkey face briefly. 00:39:04.527 --> 00:39:06.110 OK, it's going to come on in a second, 00:39:06.110 --> 00:39:07.110 and you just look at It. 00:39:07.110 --> 00:39:07.850 Here we go. 00:39:07.850 --> 00:39:10.280 Boom, there it is, OK? 00:39:10.280 --> 00:39:13.430 OK, in a moment, I'm going to show you another monkey face, 00:39:13.430 --> 00:39:15.622 and you're going to shout out same 00:39:15.622 --> 00:39:17.330 if you think it's the same, and different 00:39:17.330 --> 00:39:22.250 if you think it's different, and, huh, if you don't know. 00:39:22.250 --> 00:39:24.800 How many people don't know? 00:39:24.800 --> 00:39:27.560 Yeah, it's different, right? 00:39:27.560 --> 00:39:29.990 OK, well, OK, maybe that was too hard. 00:39:29.990 --> 00:39:31.370 Let's try it with a human, OK? 00:39:31.370 --> 00:39:32.660 Remember how hard that was? 00:39:32.660 --> 00:39:34.382 Now let's try it with a human face. 00:39:34.382 --> 00:39:35.840 I'm going to show you a human face. 00:39:35.840 --> 00:39:36.590 Everybody ready? 00:39:36.590 --> 00:39:39.420 Here we go. 00:39:39.420 --> 00:39:41.010 OK? 00:39:41.010 --> 00:39:43.260 OK, and I'm going to show you another human, 00:39:43.260 --> 00:39:45.540 and you're going to say, is it same or different? 00:39:45.540 --> 00:39:48.010 Here we go. 00:39:48.010 --> 00:39:49.330 Duh! 00:39:49.330 --> 00:39:51.250 Easy, right? 00:39:51.250 --> 00:39:55.450 OK, so here's the amazing thing. 00:39:55.450 --> 00:39:57.730 You were better at that monkey face task 00:39:57.730 --> 00:39:59.740 when you were six months old. 00:39:59.740 --> 00:40:01.570 You could do that monkey face task 00:40:01.570 --> 00:40:03.340 when you were six months old. 00:40:03.340 --> 00:40:06.040 One of the things that you have learned from experience 00:40:06.040 --> 00:40:07.960 is that you don't need that information, 00:40:07.960 --> 00:40:10.340 and you threw away your ability to do that, 00:40:10.340 --> 00:40:13.450 but you had it when you were six months old. 00:40:13.450 --> 00:40:16.300 Isn't that awesome and interesting? 00:40:16.300 --> 00:40:19.540 That's called perceptual narrowing. 00:40:19.540 --> 00:40:22.790 So the experiments, in particular, do the following. 00:40:22.790 --> 00:40:25.660 You use that preferential looking paradigm-- 00:40:25.660 --> 00:40:29.110 the preferential looking to the novel face in infants-- 00:40:29.110 --> 00:40:31.150 as your measure of discrimination ability. 00:40:31.150 --> 00:40:33.100 What can they discriminate? 00:40:33.100 --> 00:40:34.960 And so you show two human faces-- 00:40:34.960 --> 00:40:37.070 two different individuals, like this. 00:40:37.070 --> 00:40:41.140 And so now, what you see is that at six months, nine months, 00:40:41.140 --> 00:40:43.750 and adulthood, people preferentially 00:40:43.750 --> 00:40:47.505 look to the novel face more than the familiar face, OK? 00:40:47.505 --> 00:40:48.880 That's just what we've just done. 00:40:48.880 --> 00:40:54.040 People like to look at the new thing, not the old thing, OK? 00:40:54.040 --> 00:40:57.288 However, if we do six months, nine months-- oh, yeah, 00:40:57.288 --> 00:40:58.330 that's what we just said. 00:40:58.330 --> 00:40:59.450 OK, they can do that. 00:40:59.450 --> 00:41:03.010 So now, if you try this on monkey faces, 00:41:03.010 --> 00:41:07.060 you find that adults are like us. 00:41:07.060 --> 00:41:09.640 We're barely able to tell the familiar from the novel. 00:41:09.640 --> 00:41:12.070 We're not so good at monkey face discrimination. 00:41:12.070 --> 00:41:15.220 Nine-months-old are the same. 00:41:15.220 --> 00:41:20.020 But at six months, infants can discriminate 00:41:20.020 --> 00:41:25.310 the monkey faces, and you could, too, if somebody had asked you. 00:41:25.310 --> 00:41:30.080 So there's a very similar phenomena with phonemes. 00:41:30.080 --> 00:41:32.930 Those of you who are not native speakers of English 00:41:32.930 --> 00:41:35.330 maybe aware of some phonemes in English, 00:41:35.330 --> 00:41:37.760 if you learned it relatively late, that are hard for you 00:41:37.760 --> 00:41:39.380 to discriminate. 00:41:39.380 --> 00:41:41.180 There are sounds in Hindi-- 00:41:41.180 --> 00:41:43.100 I forget, it's like a "da" and a "ta," 00:41:43.100 --> 00:41:46.700 that sound identical to me, but that are just like completely 00:41:46.700 --> 00:41:49.730 obviously different to native Hindi speakers. 00:41:49.730 --> 00:41:50.960 And all languages have this. 00:41:50.960 --> 00:41:53.930 So of the kinds of phonemes that are discriminated 00:41:53.930 --> 00:41:55.700 in any language in the world, you 00:41:55.700 --> 00:41:58.795 could discriminate all of those when you were six months old. 00:41:58.795 --> 00:42:00.170 And one of the things you do when 00:42:00.170 --> 00:42:03.080 you learn a language is just throw together 00:42:03.080 --> 00:42:05.150 in the same bag things that are actually 00:42:05.150 --> 00:42:07.250 different that other people can discriminate 00:42:07.250 --> 00:42:11.150 if your language doesn't discriminate it, OK? 00:42:11.150 --> 00:42:12.650 And so you get that with phonemes, 00:42:12.650 --> 00:42:14.450 and you get it with faces. 00:42:14.450 --> 00:42:16.880 OK, everybody get what perceptual narrowing is? 00:42:16.880 --> 00:42:18.140 OK. 00:42:18.140 --> 00:42:19.850 OK, you also get this-- 00:42:19.850 --> 00:42:21.470 I mentioned this way back-- 00:42:21.470 --> 00:42:24.080 with perceiving faces of other races, right? 00:42:24.080 --> 00:42:26.600 Not just faces of other species, but if you grow up 00:42:26.600 --> 00:42:30.920 in an environment where you're only 00:42:30.920 --> 00:42:34.730 exposed to races A, B, and C, and you later 00:42:34.730 --> 00:42:36.610 have to discriminate faces of races 00:42:36.610 --> 00:42:40.190 D, E, and F, you're not so good at it, right? 00:42:40.190 --> 00:42:41.300 All the same deal. 00:42:41.300 --> 00:42:44.360 OK, all right. 00:42:44.360 --> 00:42:50.420 So how would we know whether this change between six months 00:42:50.420 --> 00:42:53.570 and older is just maturation-- it's just 00:42:53.570 --> 00:42:55.250 some kind of developmental program 00:42:55.250 --> 00:42:58.880 that's going on autopilot independent of what you see, 00:42:58.880 --> 00:43:00.620 or whether it's learned from experience? 00:43:04.070 --> 00:43:04.648 Josh? 00:43:04.648 --> 00:43:06.190 AUDIENCE: You control for experience. 00:43:06.190 --> 00:43:09.040 NANCY KANWISHER: You control for experience, absolutely, 00:43:09.040 --> 00:43:10.870 like the Sugita paper. 00:43:10.870 --> 00:43:12.710 OK, so we'll get to that in a second. 00:43:12.710 --> 00:43:14.800 So we started with these key questions-- what 00:43:14.800 --> 00:43:16.420 is the initial state at birth, and we 00:43:16.420 --> 00:43:20.620 showed impressive perceptual abilities within a few days, 00:43:20.620 --> 00:43:23.530 although people dispute whether those abilities are 00:43:23.530 --> 00:43:26.110 a face-specific system. 00:43:26.110 --> 00:43:28.600 And we don't know much about what that system is, other 00:43:28.600 --> 00:43:31.510 than it works surprisingly well given the low acuity. 00:43:31.510 --> 00:43:33.430 And we showed that how it changes after that, 00:43:33.430 --> 00:43:36.940 there's perceptual narrowing between six and 12 months, 00:43:36.940 --> 00:43:39.910 but a great deal is not known about what happens then. 00:43:39.910 --> 00:43:41.710 And so now, we're onto this question 00:43:41.710 --> 00:43:45.220 of how are we going to un-confound 00:43:45.220 --> 00:43:47.140 what changes after birth, whether it's 00:43:47.140 --> 00:43:48.718 maturation or experience. 00:43:48.718 --> 00:43:50.260 And I'm not going to have time to get 00:43:50.260 --> 00:43:51.552 to these other awesome methods. 00:43:51.552 --> 00:43:53.920 We're going to focus on controlled rearing, of what you 00:43:53.920 --> 00:43:55.540 read the Sugita paper. 00:43:55.540 --> 00:43:58.750 OK, so just to remind you of the basics, most of you 00:43:58.750 --> 00:44:00.260 seemed to get the paper just fine. 00:44:00.260 --> 00:44:02.980 The big idea was again, using this preferential looking 00:44:02.980 --> 00:44:04.870 method, what Sugita et al. 00:44:04.870 --> 00:44:08.350 Showed is that when they reared monkeys for six, 12, 00:44:08.350 --> 00:44:11.080 or 24 months without ever letting them see a face, 00:44:11.080 --> 00:44:13.600 and then tested them on the very first session 00:44:13.600 --> 00:44:19.180 that they ever saw faces with preferential looking, 00:44:19.180 --> 00:44:21.730 they found that on the very first exposure to faces, 00:44:21.730 --> 00:44:25.370 the monkeys looked more at faces compared to novel objects, 00:44:25.370 --> 00:44:25.870 right? 00:44:25.870 --> 00:44:29.050 They showed that face preference, sort of akin 00:44:29.050 --> 00:44:32.770 to infants looking at the paddle, 00:44:32.770 --> 00:44:35.740 and they discriminated between faces-- 00:44:35.740 --> 00:44:39.250 very similar faces-- with adult-like accuracy. 00:44:39.250 --> 00:44:41.570 And this part, I don't know if you found it surprising, 00:44:41.570 --> 00:44:44.500 but when this paper came out I, was like, whoa, 00:44:44.500 --> 00:44:46.270 that is crazy, right? 00:44:46.270 --> 00:44:49.660 Because as I said, the whole space of sensible hypotheses 00:44:49.660 --> 00:44:52.090 is, OK, maybe a lot of stuff is innate, 00:44:52.090 --> 00:44:54.580 but you're still going to need experience to tone it up, 00:44:54.580 --> 00:44:55.750 for God's sake, right? 00:44:55.750 --> 00:44:59.560 Who would think the entire adult ability could exist 00:44:59.560 --> 00:45:01.122 without any experience at all? 00:45:01.122 --> 00:45:02.830 So I don't know if you had that reaction, 00:45:02.830 --> 00:45:04.455 but I think that's a sensible reaction. 00:45:04.455 --> 00:45:07.900 It's a pretty astonishing finding in that paper. 00:45:07.900 --> 00:45:10.390 Unfortunately, there's one author on that paper. 00:45:10.390 --> 00:45:13.750 It was done once, and it's such a labor-intensive study 00:45:13.750 --> 00:45:16.340 that probably nobody will ever try to replicate it. 00:45:16.340 --> 00:45:19.690 So in the back of many people's minds is like, really? 00:45:19.690 --> 00:45:23.060 Can that really be true, or is there something funny here? 00:45:23.060 --> 00:45:26.780 So I hope somebody replicates it someday, 00:45:26.780 --> 00:45:28.780 but it hasn't been done yet. 00:45:28.780 --> 00:45:31.240 OK, the other thing that you guys presumably noticed 00:45:31.240 --> 00:45:33.430 is there was perceptual narrowing in that study. 00:45:33.430 --> 00:45:34.835 There were many interesting things in there. 00:45:34.835 --> 00:45:36.340 It's actually quite a rich paper. 00:45:36.340 --> 00:45:39.710 But after the initial testing session, 00:45:39.710 --> 00:45:41.380 no matter how long the deprivation, 00:45:41.380 --> 00:45:45.220 the monkeys were then housed in either an environment with just 00:45:45.220 --> 00:45:47.470 humans or just monkeys. 00:45:47.470 --> 00:45:49.810 And so whether that was 6, 12, or 24 months 00:45:49.810 --> 00:45:53.860 after birth of face deprivation, they then 00:45:53.860 --> 00:45:56.230 lost their ability, at that point, 00:45:56.230 --> 00:45:59.640 to discriminate the unexperienced faces, OK? 00:45:59.640 --> 00:46:01.390 So they went through perceptual narrowing. 00:46:01.390 --> 00:46:02.890 Does that all make sense to you guys? 00:46:02.890 --> 00:46:03.460 You got that? 00:46:03.460 --> 00:46:04.510 Good. 00:46:04.510 --> 00:46:06.940 OK, all right. 00:46:06.940 --> 00:46:09.820 So anyway, that suggests that an awful lot of the face 00:46:09.820 --> 00:46:13.630 perception system is present without any exposure to faces, 00:46:13.630 --> 00:46:15.940 and that's pretty astonishing. 00:46:15.940 --> 00:46:17.800 What experience seems to do there 00:46:17.800 --> 00:46:20.620 is not create abilities, but eliminate them 00:46:20.620 --> 00:46:24.070 right for the species that you don't see. 00:46:24.070 --> 00:46:27.610 OK, so first reaction is, really? 00:46:27.610 --> 00:46:29.050 Second reaction, is there any way 00:46:29.050 --> 00:46:32.680 to account for this in terms of some non-face-specific system? 00:46:32.680 --> 00:46:34.600 I think you can, but it takes some work, 00:46:34.600 --> 00:46:37.797 and the counter-explanations are really difficult. You can say, 00:46:37.797 --> 00:46:39.880 well, maybe this is all being carried by some more 00:46:39.880 --> 00:46:42.640 generic object system. 00:46:42.640 --> 00:46:45.790 They didn't test inverted faces, unfortunately, 00:46:45.790 --> 00:46:48.500 but if it was carried by a generic object system, 00:46:48.500 --> 00:46:50.500 why would you find the perceptual narrowing? 00:46:50.500 --> 00:46:52.120 Why would they have lost their ability 00:46:52.120 --> 00:46:54.410 for the unexperienced species? 00:46:54.410 --> 00:46:56.793 So I think that story is hard to tell. 00:46:56.793 --> 00:46:58.210 And, of course, the other question 00:46:58.210 --> 00:46:59.668 I'm sure you guys are wondering is, 00:46:59.668 --> 00:47:01.630 what is going on in those monkeys' brains? 00:47:01.630 --> 00:47:04.810 Yeah, OK, so let's get to that. 00:47:04.810 --> 00:47:07.080 Let's talk about what we know about development 00:47:07.080 --> 00:47:10.268 of this system by looking at brains. 00:47:10.268 --> 00:47:12.060 And first of all, there's been lots of work 00:47:12.060 --> 00:47:16.840 on this in older kids, age 5 and up, going back over a decade. 00:47:16.840 --> 00:47:19.380 And it's now clear that all of that basic machinery 00:47:19.380 --> 00:47:23.550 I showed you is present by age five, in most kids age five. 00:47:23.550 --> 00:47:25.870 It's continuing to change after that, 00:47:25.870 --> 00:47:29.460 but you can detect most of that stuff by age five, or six, 00:47:29.460 --> 00:47:31.090 or seven-- something like that. 00:47:31.090 --> 00:47:34.470 OK, trouble is, that's cool, but age five 00:47:34.470 --> 00:47:38.070 is late with respect to experience and with respect 00:47:38.070 --> 00:47:40.830 to all those behavioral abilities that I showed you. 00:47:40.830 --> 00:47:43.800 So we need to go earlier. 00:47:43.800 --> 00:47:46.020 And so a couple of years ago, Rebecca Sachs-- 00:47:46.020 --> 00:47:50.790 who's straight up there, two floors up-- 00:47:50.790 --> 00:47:52.770 started scanning infants, OK? 00:47:52.770 --> 00:47:56.400 And this is-- as Heather can tell you-- almost impossible. 00:47:56.400 --> 00:47:59.040 It is right on the edge. 00:47:59.040 --> 00:48:02.010 It took Rebecca and her lab many, many years of work 00:48:02.010 --> 00:48:05.498 over five years just to get the system going. 00:48:05.498 --> 00:48:07.290 There were all kinds of technical advances, 00:48:07.290 --> 00:48:10.440 like making scanning coils that were optimized for infants 00:48:10.440 --> 00:48:13.020 and comfortable for infants. 00:48:13.020 --> 00:48:14.790 Rebecca herself went to great lengths, 00:48:14.790 --> 00:48:18.390 including producing some of her own subjects. 00:48:18.390 --> 00:48:21.930 That's her son Arthur there and her two-- 00:48:21.930 --> 00:48:25.470 her grad student and postdoc who were working with her. 00:48:25.470 --> 00:48:27.750 But all of this massive effort was worth it, 00:48:27.750 --> 00:48:31.050 because what they found was, first, for comparison, 00:48:31.050 --> 00:48:35.010 this is adults with a contrast of faces versus scenes, OK? 00:48:35.010 --> 00:48:39.180 So this is basically the PPA in blue responding more to scenes, 00:48:39.180 --> 00:48:42.480 and the FFA in here and some other face-selective bits 00:48:42.480 --> 00:48:45.100 responding more to faces in adults. 00:48:45.100 --> 00:48:47.580 What do you see in six-month-old infants? 00:48:47.580 --> 00:48:49.990 It's astonishingly similar, right? 00:48:49.990 --> 00:48:53.430 You can really see a very similar layout 00:48:53.430 --> 00:48:55.410 of the functional organization of the brain 00:48:55.410 --> 00:48:58.740 already by six months. 00:48:58.740 --> 00:49:00.180 So that's a huge advance. 00:49:00.180 --> 00:49:02.895 That pushes way back the timeline by which 00:49:02.895 --> 00:49:04.020 these things had developed. 00:49:04.020 --> 00:49:05.812 Previously, everybody is talking about, oh, 00:49:05.812 --> 00:49:07.560 what changes after age five? 00:49:07.560 --> 00:49:09.340 Age five, come on? 00:49:09.340 --> 00:49:11.670 OK, it's mostly there by age six. 00:49:11.670 --> 00:49:17.160 OK, now, importantly, these systems are not adult-like. 00:49:17.160 --> 00:49:18.810 Their selectivities are very different. 00:49:18.810 --> 00:49:20.960 Those regions are less selective in infants 00:49:20.960 --> 00:49:21.960 than they are in adults. 00:49:21.960 --> 00:49:26.982 But the spatial layout is there already by six months, 00:49:26.982 --> 00:49:28.440 and that, importantly, constrains-- 00:49:28.440 --> 00:49:30.090 whatever our model is of development 00:49:30.090 --> 00:49:31.860 that pushes it way back. 00:49:31.860 --> 00:49:34.530 OK, so now, the next questions are, 00:49:34.530 --> 00:49:36.330 what is it about that region-- 00:49:36.330 --> 00:49:37.830 or those particular regions-- that 00:49:37.830 --> 00:49:43.230 makes them become face-specific already by six months? 00:49:43.230 --> 00:49:45.060 How does the face system know to take up 00:49:45.060 --> 00:49:48.370 residence in that systematic location in the brain, 00:49:48.370 --> 00:49:49.840 and what is the role of experience 00:49:49.840 --> 00:49:51.400 in their construction? 00:49:51.400 --> 00:49:53.920 And how could we ever answer this? 00:49:53.920 --> 00:49:57.520 One way to answer that is to use an animal model, OK? 00:49:57.520 --> 00:50:00.380 So there's been-- yes. 00:50:00.380 --> 00:50:02.750 AUDIENCE: OK, yeah, similar question about-- 00:50:02.750 --> 00:50:04.500 NANCY KANWISHER: I'm sorry, I didn't hear. 00:50:04.500 --> 00:50:04.950 About what? 00:50:04.950 --> 00:50:06.408 AUDIENCE: General physical layout-- 00:50:06.408 --> 00:50:10.260 like why does your stomach always come in the same place, 00:50:10.260 --> 00:50:13.920 and would it maybe be the same mechanism that 00:50:13.920 --> 00:50:17.670 guides development of any organs and the layout of the body, 00:50:17.670 --> 00:50:19.450 [INAUDIBLE]? 00:50:19.450 --> 00:50:20.440 NANCY KANWISHER: Yes. 00:50:20.440 --> 00:50:23.770 Now, I don't know much about how hearts, and kidneys, and livers 00:50:23.770 --> 00:50:28.270 develop, but my understanding is that's pretty much wired in. 00:50:28.270 --> 00:50:33.280 There's some chunks of DNA that tell you how to build a kidney 00:50:33.280 --> 00:50:35.380 and where to put it in your body, right? 00:50:35.380 --> 00:50:37.600 And so that is one of the hypotheses here. 00:50:37.600 --> 00:50:39.400 It's a tempting hypothesis, right? 00:50:39.400 --> 00:50:40.750 There's all that structure. 00:50:40.750 --> 00:50:43.690 It's a very tempting hypothesis, but that doesn't 00:50:43.690 --> 00:50:45.340 mean it's necessarily right. 00:50:45.340 --> 00:50:46.705 Yeah, it absolutely is. 00:50:46.705 --> 00:50:50.140 It's a hypothesis we should consider and take seriously, 00:50:50.140 --> 00:50:50.980 yeah. 00:50:50.980 --> 00:50:52.930 OK, so but we want data. 00:50:52.930 --> 00:50:53.890 We want to find out. 00:50:53.890 --> 00:50:55.900 OK, so animal models. 00:50:55.900 --> 00:50:58.803 So starting a few years ago, Marge Livingstone over 00:50:58.803 --> 00:51:00.220 at Harvard Med School over there-- 00:51:00.220 --> 00:51:02.140 a couple of miles over there-- 00:51:02.140 --> 00:51:04.270 started doing these also really amazingly 00:51:04.270 --> 00:51:07.388 heroic studies where she was scanning infant monkeys. 00:51:07.388 --> 00:51:08.930 OK, now, this is really hard to read, 00:51:08.930 --> 00:51:10.540 so let me tell you what we got here. 00:51:10.540 --> 00:51:12.320 We have the cortex. 00:51:12.320 --> 00:51:14.740 This is all the same animal at different time points, 00:51:14.740 --> 00:51:16.720 and each of these things is the cortex 00:51:16.720 --> 00:51:18.670 unfolded mathematically and flattened 00:51:18.670 --> 00:51:20.240 so you can see the whole thing. 00:51:20.240 --> 00:51:21.907 I don't expect you to know what's where. 00:51:21.907 --> 00:51:23.710 I can barely tell myself. 00:51:23.710 --> 00:51:27.970 But if you look at it, what you see is at 81 days of age, 00:51:27.970 --> 00:51:29.200 there's just blue stuff. 00:51:29.200 --> 00:51:31.030 There's no orange stuff. 00:51:31.030 --> 00:51:34.030 The orange stuff is the face-selective response. 00:51:34.030 --> 00:51:35.530 In fact, if you look down, you start 00:51:35.530 --> 00:51:38.400 to see, oh, that looks-- yeah, yeah, OK, that 00:51:38.400 --> 00:51:39.400 looks pretty systematic. 00:51:39.400 --> 00:51:41.770 It starts replicating after that. 00:51:41.770 --> 00:51:45.490 And so the claim is you don't see face selectivity 00:51:45.490 --> 00:51:49.120 until about 170 days after birth in monkeys. 00:51:49.120 --> 00:51:50.410 OK, that's about here. 00:51:50.410 --> 00:51:52.390 Here's another monkey for comparison. 00:51:52.390 --> 00:51:53.920 If you stare at it, you'll see, OK, 00:51:53.920 --> 00:51:56.710 there's these systematic bits-- boom, boom, boom, boom-- 00:51:56.710 --> 00:52:00.130 and maybe a little hint at 170, but-- there's 00:52:00.130 --> 00:52:03.700 some garbage up there, but nothing systematic before that. 00:52:03.700 --> 00:52:04.330 Yeah? 00:52:04.330 --> 00:52:06.970 AUDIENCE: So there's no control of the environment? 00:52:06.970 --> 00:52:08.950 This is like monkeys-- 00:52:08.950 --> 00:52:10.420 NANCY KANWISHER: Normal monkeys who 00:52:10.420 --> 00:52:13.690 have exposure to human faces and monkey faces hanging out 00:52:13.690 --> 00:52:14.412 in the lab, yeah. 00:52:14.412 --> 00:52:16.120 We haven't gotten to control rearing yet. 00:52:16.120 --> 00:52:16.930 It's coming. 00:52:16.930 --> 00:52:20.310 OK, first thing is just, when does it develop in monkeys? 00:52:20.310 --> 00:52:21.520 OK, all right. 00:52:21.520 --> 00:52:24.760 So are you surprised by this? 00:52:24.760 --> 00:52:27.550 It's not there here, and it is there there. 00:52:27.550 --> 00:52:29.120 You should be surprised. 00:52:29.120 --> 00:52:30.130 Why are you surprised? 00:52:33.417 --> 00:52:34.750 This is what you guys predicted. 00:52:34.750 --> 00:52:36.910 Quiley? 00:52:36.910 --> 00:52:39.160 AUDIENCE: I guess I'm surprised because they 00:52:39.160 --> 00:52:40.520 were able to discriminate. 00:52:40.520 --> 00:52:43.800 NANCY KANWISHER: Yeah, what is up with that? 00:52:43.800 --> 00:52:45.180 Absolutely! 00:52:45.180 --> 00:52:47.730 The Sugida paper really made it look like that system was 00:52:47.730 --> 00:52:49.020 innate, right? 00:52:49.020 --> 00:52:50.490 No experience-- boom! 00:52:50.490 --> 00:52:51.070 They're fine. 00:52:51.070 --> 00:52:53.790 It was just behavior, but it was a good behavioral study. 00:52:53.790 --> 00:52:57.640 So why the hell isn't it here? 00:52:57.640 --> 00:53:01.570 Everybody with the program on how surprising that is? 00:53:01.570 --> 00:53:04.250 OK, so a bunch of things. 00:53:04.250 --> 00:53:06.850 First of all-- and it gets stable after that, 00:53:06.850 --> 00:53:08.350 and replicable. 00:53:08.350 --> 00:53:11.380 Well, the first thing is one's a behavioral measure, 00:53:11.380 --> 00:53:12.970 and one's a neural measure. 00:53:12.970 --> 00:53:15.100 Maybe those fabulous behavioral measures 00:53:15.100 --> 00:53:18.520 weren't actually being driven by some face-specific system. 00:53:18.520 --> 00:53:20.140 Wouldn't that be sad, right? 00:53:20.140 --> 00:53:21.640 I mean, they did lots of controls. 00:53:21.640 --> 00:53:22.810 It was a nice idea. 00:53:22.810 --> 00:53:25.360 I thought they did as well as they could, but who knows? 00:53:25.360 --> 00:53:28.188 Maybe those monkeys could do that task 00:53:28.188 --> 00:53:30.730 with some other system and they didn't need their face system 00:53:30.730 --> 00:53:31.670 for it. 00:53:31.670 --> 00:53:33.250 That's one possibility, right? 00:53:33.250 --> 00:53:35.980 Then, you could have the face system not develop till later, 00:53:35.980 --> 00:53:38.440 but the monkeys could do it before. 00:53:38.440 --> 00:53:42.640 But the other thing is, notice that Sugita 00:53:42.640 --> 00:53:46.450 didn't test their monkeys until, with the youngest ones, 00:53:46.450 --> 00:53:49.310 six months of age. 00:53:49.310 --> 00:53:53.740 So maybe it just got wired up just before-- 00:53:53.740 --> 00:53:56.440 right there-- they were tested, OK? 00:53:56.440 --> 00:53:57.940 So it seemed contradictory at first, 00:53:57.940 --> 00:54:02.930 but it's not completely, literally contradictory, yeah? 00:54:02.930 --> 00:54:10.130 OK, all right, so now, the fact that this stuff doesn't show up 00:54:10.130 --> 00:54:14.930 until here, does that mean that this face system requires 00:54:14.930 --> 00:54:15.905 experience to develop? 00:54:19.990 --> 00:54:22.770 You know the answer, because whenever I ask that question, 00:54:22.770 --> 00:54:24.660 the answer is always no. 00:54:24.660 --> 00:54:28.530 Why does that not imply that you need experience 00:54:28.530 --> 00:54:30.000 with faces to wire up? 00:54:30.000 --> 00:54:30.690 It's tempting. 00:54:30.690 --> 00:54:31.680 You look at it, and it's like, OK, 00:54:31.680 --> 00:54:33.240 you had to look at faces all this time 00:54:33.240 --> 00:54:34.198 before you wired it up. 00:54:34.198 --> 00:54:35.190 Boom, there it is-- 00:54:35.190 --> 00:54:37.300 very tempting. 00:54:37.300 --> 00:54:39.210 But-- is it Jessica, no? 00:54:39.210 --> 00:54:40.770 Sorry, what's your name? 00:54:40.770 --> 00:54:41.270 Yeah. 00:54:41.270 --> 00:54:42.320 AUDIENCE: Bele. 00:54:42.320 --> 00:54:42.672 NANCY KANWISHER: Bele. 00:54:42.672 --> 00:54:44.600 Oh, sorry, you told me that like six times. 00:54:44.600 --> 00:54:48.465 AUDIENCE: I could be merely due to mature, physical. 00:54:48.465 --> 00:54:50.590 NANCY KANWISHER: Yeah, it could be just maturation. 00:54:50.590 --> 00:54:53.090 I keep making the same point, because it's important, right? 00:54:53.090 --> 00:54:54.700 Just because it shows up later doesn't 00:54:54.700 --> 00:54:56.500 mean it's learned, right? 00:54:56.500 --> 00:54:58.660 Maybe it's like puberty, or height, or something 00:54:58.660 --> 00:55:00.868 like that that's on some developmental program that's 00:55:00.868 --> 00:55:04.450 just going to unfold independent of what you see, OK? 00:55:04.450 --> 00:55:07.330 So how would we find out? 00:55:07.330 --> 00:55:08.860 We would do controlled rearing. 00:55:08.860 --> 00:55:12.520 And that's exactly what these guys did, OK? 00:55:12.520 --> 00:55:16.180 So in another paper that just came out a couple of years ago, 00:55:16.180 --> 00:55:19.030 they raised baby monkeys without ever letting them see a face. 00:55:19.030 --> 00:55:21.760 Much like Sugita did, they use welder's masks 00:55:21.760 --> 00:55:24.100 every time they were in the lab, so the monkeys never 00:55:24.100 --> 00:55:25.300 got to see faces. 00:55:25.300 --> 00:55:27.520 And like Sugita, they went to lengths 00:55:27.520 --> 00:55:29.260 to treat the monkeys nicely. 00:55:29.260 --> 00:55:31.720 They heard the calls of their com-specifics, 00:55:31.720 --> 00:55:35.080 they got lots of attention, they had rich visual experience. 00:55:35.080 --> 00:55:36.610 They just didn't see faces. 00:55:36.610 --> 00:55:38.828 So it sounds kind of tragic and horrible at first, 00:55:38.828 --> 00:55:40.120 but it's actually not that bad. 00:55:40.120 --> 00:55:42.490 They had social contact and visual experience. 00:55:42.490 --> 00:55:45.520 They just never saw faces-- 00:55:45.520 --> 00:55:47.620 both this study and the Sugita study. 00:55:47.620 --> 00:55:53.200 All right, OK, so they could hear and smell other monkeys. 00:55:53.200 --> 00:55:56.050 So the face-deprived monkeys saw no faces at all 00:55:56.050 --> 00:55:58.250 until 90 days old. 00:55:58.250 --> 00:56:01.420 And at that point, they went straight into the scanner, OK? 00:56:01.420 --> 00:56:03.820 And the first time they saw faces was inside an MRI 00:56:03.820 --> 00:56:07.480 machine getting scanned, OK? 00:56:07.480 --> 00:56:08.610 So what do you think? 00:56:08.610 --> 00:56:11.395 Are the face-deprived monkeys going to show face patches? 00:56:16.513 --> 00:56:18.055 So there's no way to tell, because we 00:56:18.055 --> 00:56:23.350 have all these contradictory bits of evidence here, right? 00:56:23.350 --> 00:56:25.255 From Sugita, you might think yes. 00:56:29.830 --> 00:56:30.430 Hard to tell. 00:56:30.430 --> 00:56:32.030 So let's just look at the data. 00:56:32.030 --> 00:56:36.520 OK So here first is a normally normally reared monkey 00:56:36.520 --> 00:56:39.370 260 days old just for comparison. 00:56:39.370 --> 00:56:44.230 And those face patches in yellow in two different monkeys here, 00:56:44.230 --> 00:56:46.720 B4 and B5, left and right hemisphere. 00:56:46.720 --> 00:56:48.910 OK, so those yellow bits are the face patches. 00:56:48.910 --> 00:56:51.910 OK, normal 260-day-old monkey. 00:56:51.910 --> 00:56:54.230 Now we're going to see a face-deprived monkey, 00:56:54.230 --> 00:56:55.370 260 days old. 00:56:55.370 --> 00:56:58.180 This monkey was face-deprived that entire time up 00:56:58.180 --> 00:56:59.680 until scanning. 00:56:59.680 --> 00:57:02.630 No face patches. 00:57:02.630 --> 00:57:08.460 The plot thickens-- no face patches at all. 00:57:08.460 --> 00:57:11.670 So these guys published this paper in a very high-profile 00:57:11.670 --> 00:57:13.200 journal and said-- 00:57:13.200 --> 00:57:14.520 this is the title of paper-- 00:57:14.520 --> 00:57:18.990 "Seeing faces is necessary for face-domain formation," OK? 00:57:18.990 --> 00:57:21.860 Face domain just means face-selective patch. 00:57:21.860 --> 00:57:24.860 OK, everybody see? 00:57:24.860 --> 00:57:28.880 You deprive them of face experience, you don't see it. 00:57:28.880 --> 00:57:32.600 OK, that's pretty interesting, and it strongly 00:57:32.600 --> 00:57:35.270 suggests that the face system is not innate but depends 00:57:35.270 --> 00:57:39.620 on face experience, doesn't it? 00:57:39.620 --> 00:57:43.760 Rare case where the answer is, yes, it does. 00:57:43.760 --> 00:57:48.210 And it feels like it contradicts the Sugita finding, right? 00:57:48.210 --> 00:57:49.800 But not exactly. 00:57:49.800 --> 00:57:51.810 You could still wiggle out of it, right? 00:57:51.810 --> 00:57:54.630 You could say, OK, the thing that Sugita 00:57:54.630 --> 00:57:57.250 was studying doesn't use those patches, 00:57:57.250 --> 00:57:58.800 so it's not flat out contradictory. 00:57:58.800 --> 00:58:00.778 Sugita was measuring behavior; these guys 00:58:00.778 --> 00:58:01.695 are looking at brains. 00:58:01.695 --> 00:58:04.230 So it's kind of unsatisfying, but it's, in principle, 00:58:04.230 --> 00:58:06.600 possible. 00:58:06.600 --> 00:58:08.850 Me and everyone else has been nudging these guys 00:58:08.850 --> 00:58:12.030 to run the Sugita behavioral experiment on your monkeys, 00:58:12.030 --> 00:58:13.080 please! 00:58:13.080 --> 00:58:14.520 And I gather that's getting going, 00:58:14.520 --> 00:58:16.935 but I haven't seen any of the data yet. 00:58:16.935 --> 00:58:18.810 So we don't know how that's going to resolve. 00:58:18.810 --> 00:58:20.937 OK, so let's take stock. 00:58:20.937 --> 00:58:22.020 What is the initial state? 00:58:22.020 --> 00:58:24.120 We show with behavior that there is 00:58:24.120 --> 00:58:27.090 both attention to faces and-- 00:58:27.090 --> 00:58:31.230 present in newborn humans, and face specificity seems like it, 00:58:31.230 --> 00:58:34.890 but it's not totally nailed, whereas functional MRI says 00:58:34.890 --> 00:58:37.830 there's no evidence for face specificity at birth-- 00:58:37.830 --> 00:58:39.720 at least in monkeys, right? 00:58:39.720 --> 00:58:40.740 That's other. 00:58:40.740 --> 00:58:42.870 Yeah, OK, so how are we going to reconcile this 00:58:42.870 --> 00:58:45.090 with all the behavioral results I showed you, 00:58:45.090 --> 00:58:47.340 that there seems to be a lot of face abilities 00:58:47.340 --> 00:58:49.050 present in newborns? 00:58:49.050 --> 00:58:53.280 Well, one possibility is that face specificity exists 00:58:53.280 --> 00:58:57.510 behaviorally, but MRI fails-- oh, sorry, face specificity 00:58:57.510 --> 00:59:00.850 exists in the brain, but MRI fails to detect it. 00:59:00.850 --> 00:59:03.480 There's a whole rigmarole about whether functional MRI works 00:59:03.480 --> 00:59:04.260 well in infants. 00:59:04.260 --> 00:59:06.000 It's barely possible, as I mentioned. 00:59:06.000 --> 00:59:07.890 It's also hard with infant monkeys. 00:59:07.890 --> 00:59:10.020 Their blood flow regulation is different. 00:59:10.020 --> 00:59:12.270 They're squirming and wiggling. 00:59:12.270 --> 00:59:14.430 There are a million issues with scanning babies, 00:59:14.430 --> 00:59:15.580 whether human or monkey. 00:59:15.580 --> 00:59:17.580 And so you could always say, well, it was there, 00:59:17.580 --> 00:59:19.740 and just the MRI data are just kind of crappy, 00:59:19.740 --> 00:59:21.840 or blood flow regulation to the brain 00:59:21.840 --> 00:59:25.290 develops later-- an argument many people have made. 00:59:25.290 --> 00:59:27.030 However, a paper was published last week 00:59:27.030 --> 00:59:29.730 that argues against that hypothesis. 00:59:29.730 --> 00:59:33.750 The same group just showed that the somatosensory touch 00:59:33.750 --> 00:59:39.180 system is totally in place by 11 days in baby monkeys. 00:59:39.180 --> 00:59:41.910 So that suggests that you can get really nice functional MRI 00:59:41.910 --> 00:59:44.280 data at 11 days of age in baby monkeys, 00:59:44.280 --> 00:59:46.650 and it makes it less likely that this 00:59:46.650 --> 00:59:49.290 is some kind of spurious failure to detect something 00:59:49.290 --> 00:59:51.810 that was actually there. 00:59:51.810 --> 00:59:54.060 I'm not going to test you on every little detail here. 00:59:54.060 --> 00:59:55.810 I want you to think about the logic of how 00:59:55.810 --> 00:59:58.770 you can ask these questions. 00:59:58.770 --> 01:00:01.677 OK, the other possibility is that the face abilities 01:00:01.677 --> 01:00:04.260 that we showed behaviorally are using some more generic object 01:00:04.260 --> 01:00:07.770 recognition system, not using this face-selective system 01:00:07.770 --> 01:00:09.460 in the brain. 01:00:09.460 --> 01:00:12.950 OK, so how does it change over time? 01:00:12.950 --> 01:00:14.650 Well, we showed that behaviorally-- 01:00:14.650 --> 01:00:16.510 in humans, at least-- all the hallmarks 01:00:16.510 --> 01:00:19.300 of face-specific processing or present by age four, 01:00:19.300 --> 01:00:21.670 and we get this perceptual narrowing between six and 12 01:00:21.670 --> 01:00:23.485 months. 01:00:23.485 --> 01:00:25.360 But then we showed that with functional MRI-- 01:00:25.360 --> 01:00:26.350 at least in monkeys-- 01:00:26.350 --> 01:00:30.140 there's no evidence for face specificity before 200 days, 01:00:30.140 --> 01:00:30.640 right? 01:00:30.640 --> 01:00:33.460 AUDIENCE: [INAUDIBLE]? 01:00:33.460 --> 01:00:36.280 NANCY KANWISHER: I gather they're working on it, 01:00:36.280 --> 01:00:38.740 but I haven't seen any of the data yet, yeah. 01:00:42.350 --> 01:00:45.980 OK, so that lack of face specificity 01:00:45.980 --> 01:00:47.960 is consistent with the idea that all 01:00:47.960 --> 01:00:50.690 that human early face recognition behavior 01:00:50.690 --> 01:00:52.430 is driven by a different system-- 01:00:52.430 --> 01:00:55.610 because they don't have their face system yet, presumably. 01:00:55.610 --> 01:00:58.490 But it's also consistent with this idea 01:00:58.490 --> 01:01:01.340 that it's just failing to be detected. 01:01:01.340 --> 01:01:03.530 Even though I said that's probably not true, 01:01:03.530 --> 01:01:07.250 given you can detect other stuff, it might be true here. 01:01:07.250 --> 01:01:09.190 The ability to see things with MRI 01:01:09.190 --> 01:01:11.750 depends where you're looking at the brain. 01:01:11.750 --> 01:01:15.320 OK, so what about these causal roles 01:01:15.320 --> 01:01:20.210 of structured experience and biological maturation? 01:01:20.210 --> 01:01:22.970 OK, so we argued that early face experience 01:01:22.970 --> 01:01:25.160 isn't crucial for the face recognition system. 01:01:25.160 --> 01:01:27.080 That was the Sugita paper you read. 01:01:27.080 --> 01:01:30.530 But now, functional MRI is showing that face experience 01:01:30.530 --> 01:01:34.070 is necessary for the development of face patches, at least 01:01:34.070 --> 01:01:35.540 in monkeys. 01:01:35.540 --> 01:01:38.475 And so a very sensible reaction, is what, what, what? 01:01:38.475 --> 01:01:40.100 How are we going to make sense of this? 01:01:40.100 --> 01:01:41.983 This is a big conundrum. 01:01:41.983 --> 01:01:44.150 It's going to get worse on Monday, where there's yet 01:01:44.150 --> 01:01:47.480 more contradictory data. 01:01:47.480 --> 01:01:52.750 And further, if that face system isn't innate, 01:01:52.750 --> 01:01:57.670 then what, if anything, is innate about face perception, 01:01:57.670 --> 01:01:58.210 right? 01:01:58.210 --> 01:02:04.070 So maybe what all these data are telling us is, not that much. 01:02:04.070 --> 01:02:07.220 Maybe just a biased look at faces, 01:02:07.220 --> 01:02:09.440 or some very simple image template 01:02:09.440 --> 01:02:11.750 that's sufficient in the environment of infants 01:02:11.750 --> 01:02:14.330 to get them to look at faces. 01:02:14.330 --> 01:02:16.280 So there's a lot of studies I didn't have time 01:02:16.280 --> 01:02:18.680 to work into this lecture, where people stick cameras 01:02:18.680 --> 01:02:21.560 on the foreheads of newborns, and they 01:02:21.560 --> 01:02:24.560 collect, what is the typical visual experience of a newborn? 01:02:24.560 --> 01:02:26.030 And then, you can take that-- 01:02:26.030 --> 01:02:29.345 you can take that experience and ask, what kind of-- 01:02:29.345 --> 01:02:31.790 you can write machine learning code 01:02:31.790 --> 01:02:34.700 to say, what would you have to build in to reliably pick out 01:02:34.700 --> 01:02:37.820 the faces in typical infant input? 01:02:37.820 --> 01:02:39.710 And it's probably not that complicated, 01:02:39.710 --> 01:02:42.350 because infants don't see that many different kinds of things, 01:02:42.350 --> 01:02:43.220 right? 01:02:43.220 --> 01:02:44.840 OK. 01:02:44.840 --> 01:02:47.930 We showed early visual discrimination abilities 01:02:47.930 --> 01:02:50.030 of faces in newborn infants. 01:02:50.030 --> 01:02:51.770 But again, it's not clear that's part 01:02:51.770 --> 01:02:54.218 of the face-specific system. 01:02:54.218 --> 01:02:55.760 And we showed that the face patches-- 01:02:55.760 --> 01:02:56.870 at least in monkeys-- 01:02:56.870 --> 01:02:59.930 seem to require experience, OK? 01:02:59.930 --> 01:03:02.060 I'm just recapping here. 01:03:02.060 --> 01:03:03.980 But now, there's this big question of, 01:03:03.980 --> 01:03:08.120 how do those face patches know where to develop in the brain? 01:03:08.120 --> 01:03:11.030 Like here they are in humans, these little purple blobs. 01:03:11.030 --> 01:03:14.270 The occipital face area I've got two different fusiform face 01:03:14.270 --> 01:03:17.030 areas, because various people think there's two. 01:03:17.030 --> 01:03:17.760 I'm not sure. 01:03:17.760 --> 01:03:19.260 I don't really care; doesn't matter. 01:03:19.260 --> 01:03:22.180 Anyway, how do they know to land right there? 01:03:22.180 --> 01:03:24.680 OK, we keep bringing up this question and dancing around it, 01:03:24.680 --> 01:03:29.690 but so far, I've given no basis for thinking about this. 01:03:29.690 --> 01:03:33.920 One possibility is that infants-- 01:03:33.920 --> 01:03:37.220 monkey and humans-- are born with some earlier 01:03:37.220 --> 01:03:40.110 kind of selectivity of that patch of brain. 01:03:40.110 --> 01:03:41.870 It's not a whole face template. 01:03:41.870 --> 01:03:43.700 It's not a whole face system. 01:03:43.700 --> 01:03:47.480 Maybe it's a bias for curvy things, right? 01:03:47.480 --> 01:03:50.750 And then, somehow, that makes the faces land there, 01:03:50.750 --> 01:03:52.340 and the system wires itself up. 01:03:52.340 --> 01:03:54.380 It's not exactly clear how that would go. 01:03:54.380 --> 01:03:57.590 But that's one kind of story. 01:03:57.590 --> 01:03:59.208 Another story is based on this fact 01:03:59.208 --> 01:04:01.250 I told you at the beginning of the lecture, which 01:04:01.250 --> 01:04:04.670 is most of the long-range connectivity of the brain is 01:04:04.670 --> 01:04:06.050 present at birth. 01:04:06.050 --> 01:04:08.270 And so maybe the particular connections 01:04:08.270 --> 01:04:11.840 of that patch of brain are already there at birth, 01:04:11.840 --> 01:04:13.760 and maybe that patch of connections 01:04:13.760 --> 01:04:18.410 are sufficient to somehow gate the input to that system 01:04:18.410 --> 01:04:24.130 and arrange for it to end up being face-specific, OK? 01:04:24.130 --> 01:04:27.760 So this is a very active area of investigation, 01:04:27.760 --> 01:04:31.482 and there's other very active, ongoing kinds of investigation 01:04:31.482 --> 01:04:33.190 where people are trying to understand how 01:04:33.190 --> 01:04:34.970 this development might work. 01:04:34.970 --> 01:04:36.580 One way people are looking at this-- 01:04:36.580 --> 01:04:38.122 I mentioned this briefly, but I think 01:04:38.122 --> 01:04:40.210 it's super exciting-- is people are asking 01:04:40.210 --> 01:04:42.370 with deep nets and other kinds of modeling, what 01:04:42.370 --> 01:04:45.940 do you have to build into a system to get it to produce 01:04:45.940 --> 01:04:48.100 face recognition abilities? 01:04:48.100 --> 01:04:49.660 If you're trying to make a deep net, 01:04:49.660 --> 01:04:52.060 you're trying to make it really good at face recognition, 01:04:52.060 --> 01:04:54.970 do you need to give it a template of faces? 01:04:54.970 --> 01:04:57.100 Do you need to give it only experience with faces? 01:04:57.100 --> 01:04:58.990 What do you need to build into it to get 01:04:58.990 --> 01:05:00.580 it to be really good, right? 01:05:00.580 --> 01:05:04.420 And so that's a very active area of investigation. 01:05:04.420 --> 01:05:07.690 And you can actually-- with some ongoing work with Jim DiCarlo's 01:05:07.690 --> 01:05:10.420 lab, we're asking, OK, deep nets don't have topography. 01:05:10.420 --> 01:05:12.940 Next door units in a deep net doesn't mean anything, what's 01:05:12.940 --> 01:05:14.320 next door versus far apart. 01:05:14.320 --> 01:05:16.282 Location doesn't mean anything in a deep net, 01:05:16.282 --> 01:05:17.740 but you can make it mean something. 01:05:17.740 --> 01:05:20.470 And then you can ask when, and whether, and how, 01:05:20.470 --> 01:05:25.030 and why you get face patches in a deep net and what 01:05:25.030 --> 01:05:26.980 computational role they serve. 01:05:26.980 --> 01:05:29.680 Well, totally weirdly, I'm finishing early, 01:05:29.680 --> 01:05:31.000 but I'm not going to finish. 01:05:31.000 --> 01:05:32.417 I'll take questions, and then I'll 01:05:32.417 --> 01:05:34.420 maybe add a little bit more. 01:05:34.420 --> 01:05:36.970 I think that was all I had here, right. 01:05:36.970 --> 01:05:38.823 Any questions about all this? 01:05:38.823 --> 01:05:40.240 If it feels a little bit chaotic-- 01:05:40.240 --> 01:05:42.340 I've sort of said x and not x, and x, 01:05:42.340 --> 01:05:44.620 although they're not exactly x and not x. 01:05:44.620 --> 01:05:46.210 They're just-- yeah, Sirdul. 01:05:46.210 --> 01:05:49.600 AUDIENCE: So the fMRI tends to [INAUDIBLE] activity 01:05:49.600 --> 01:05:51.100 in boxes, right? 01:05:51.100 --> 01:05:54.800 [INAUDIBLE] you said contain millions of neurons. 01:05:54.800 --> 01:05:57.700 So is it possible that the neurons 01:05:57.700 --> 01:06:00.730 that are specific to faces are distributed 01:06:00.730 --> 01:06:03.430 at an early age throughout the brain, and somehow 01:06:03.430 --> 01:06:05.323 the function for them-- 01:06:05.323 --> 01:06:07.240 NANCY KANWISHER: They get spatially clustered. 01:06:07.240 --> 01:06:08.990 AUDIENCE: Yeah, but the neurons themselves 01:06:08.990 --> 01:06:10.483 already exist at birth? 01:06:10.483 --> 01:06:11.650 NANCY KANWISHER: Absolutely. 01:06:11.650 --> 01:06:12.850 That's a great hypothesis. 01:06:12.850 --> 01:06:13.930 It's absolutely possible. 01:06:13.930 --> 01:06:15.130 Everybody get the idea? 01:06:15.130 --> 01:06:17.560 You have all those face neurons at birth, 01:06:17.560 --> 01:06:19.270 and maybe they're face-specific at birth, 01:06:19.270 --> 01:06:21.250 but they're spatially spread out. 01:06:21.250 --> 01:06:23.650 And then they have to find each other 01:06:23.650 --> 01:06:25.390 and hang out together next to each other 01:06:25.390 --> 01:06:27.130 before you ever get an MRI signal. 01:06:27.130 --> 01:06:29.410 It's totally possible logically. 01:06:29.410 --> 01:06:32.290 It seems to be quite unlikely actually, 01:06:32.290 --> 01:06:34.750 because it would be very hard for all those neurons, 01:06:34.750 --> 01:06:36.792 with their necessary connections-- which is, 01:06:36.792 --> 01:06:38.500 after all, how they become face-specific, 01:06:38.500 --> 01:06:40.833 is what their inputs are and what they're connected to-- 01:06:40.833 --> 01:06:43.000 it'd be very hard for them to migrate spatially 01:06:43.000 --> 01:06:45.428 across the brain maintaining their connections. 01:06:45.428 --> 01:06:46.720 Yes, you're going to push back? 01:06:46.720 --> 01:06:47.220 Go for it. 01:06:47.220 --> 01:06:50.200 AUDIENCE: Well, I think [INAUDIBLE] 01:06:50.200 --> 01:06:52.680 But since you said [INAUDIBLE],, they 01:06:52.680 --> 01:06:54.430 care about what their neighbors are doing. 01:06:54.430 --> 01:06:57.100 So maybe it's just like a neighboring neuron's 01:06:57.100 --> 01:07:00.820 properties, but the [INAUDIBLE] in this chain 01:07:00.820 --> 01:07:03.610 moves it back until that brief [INAUDIBLE].. 01:07:03.610 --> 01:07:06.910 But that progression is the most efficient way to pop up. 01:07:06.910 --> 01:07:10.210 NANCY KANWISHER: It's totally possible, totally possible, 01:07:10.210 --> 01:07:11.320 absolutely. 01:07:11.320 --> 01:07:13.870 Yep, other questions? 01:07:13.870 --> 01:07:15.010 And this is wide open. 01:07:15.010 --> 01:07:16.450 Nobody knows, right? 01:07:19.310 --> 01:07:21.635 Let me just see what else I have time for briefly. 01:07:27.010 --> 01:07:28.600 So funny, I took out all these slides 01:07:28.600 --> 01:07:31.240 because I just thought I'm not going to run out of time, 01:07:31.240 --> 01:07:32.920 and go over, and drive everyone crazy. 01:07:38.400 --> 01:07:41.820 I moved all this stuff to the other lecture. 01:07:41.820 --> 01:07:42.765 Maybe I will just-- 01:07:47.197 --> 01:07:48.780 All right, hang on, let me just glance 01:07:48.780 --> 01:07:52.290 at the lineup for Wednesday. 01:07:54.900 --> 01:07:55.610 Yeah? 01:07:55.610 --> 01:07:58.650 AUDIENCE: Is there-- the perceptual narrowing 01:07:58.650 --> 01:08:02.430 is really surprising and fascinating. 01:08:02.430 --> 01:08:09.240 Does anybody have a model for how that processing might work 01:08:09.240 --> 01:08:10.950 or what it might be for? 01:08:10.950 --> 01:08:13.710 I mean, it feels like a lot of it-- 01:08:13.710 --> 01:08:17.850 assumptions, or the common sense assumptions 01:08:17.850 --> 01:08:22.184 when we look at fMRI, and when we look at neural signals 01:08:22.184 --> 01:08:25.470 is that they all mean positive things. 01:08:25.470 --> 01:08:28.200 But maybe a lot of that signals, a lot of activity 01:08:28.200 --> 01:08:29.939 might be inhibitory-- 01:08:29.939 --> 01:08:31.828 might be the opposite. 01:08:31.828 --> 01:08:33.120 NANCY KANWISHER: Totally, yeah. 01:08:33.120 --> 01:08:35.760 But how would that explain perceptual narrowing? 01:08:35.760 --> 01:08:38.880 AUDIENCE: Well, if what you're learning is what to ignore, 01:08:38.880 --> 01:08:42.840 then maybe it takes a lot of effort to ignore things. 01:08:42.840 --> 01:08:46.889 And not really sure. 01:08:46.889 --> 01:08:48.420 I'm not sure exactly, yeah. 01:08:48.420 --> 01:08:49.350 NANCY KANWISHER: No, it's a good point. 01:08:49.350 --> 01:08:51.010 Like I mentioned at the beginning, 01:08:51.010 --> 01:08:54.689 one of the limitations of functional MRI 01:08:54.689 --> 01:08:57.120 is we don't know what the actual neurophysiological basis 01:08:57.120 --> 01:08:58.450 of the bold signal is. 01:08:58.450 --> 01:09:01.649 It could be anything that increases your metabolic costs, 01:09:01.649 --> 01:09:03.390 and hence changes blood flow. 01:09:03.390 --> 01:09:05.609 But one of the things that increases metabolic costs 01:09:05.609 --> 01:09:07.979 is inhibiting other neurons. 01:09:07.979 --> 01:09:10.290 And so way back in the early days of, actually, 01:09:10.290 --> 01:09:12.840 PET imaging, before functional MRI came along, 01:09:12.840 --> 01:09:16.529 there was an early proto version of a face-specific paper. 01:09:16.529 --> 01:09:20.760 It didn't nail everything, but it was not bad for 1981, 01:09:20.760 --> 01:09:22.740 when I think it was published. 01:09:22.740 --> 01:09:24.270 And the person who did that paper, 01:09:24.270 --> 01:09:29.310 Justine Sergent argued that it's very, very ambiguous 01:09:29.310 --> 01:09:31.740 what it means to find a hotspot in the brain 01:09:31.740 --> 01:09:33.930 where the activity-- the metabolic activity-- 01:09:33.930 --> 01:09:36.571 is higher, say, when you look at faces than objects. 01:09:36.571 --> 01:09:39.029 And her point was, that could be the part of the brain that 01:09:39.029 --> 01:09:41.290 really sucks at face recognition. 01:09:41.290 --> 01:09:42.750 That's the part that's going, ah, 01:09:42.750 --> 01:09:44.160 I can't deal with this thing! 01:09:44.160 --> 01:09:45.700 What is this thing, right! 01:09:45.700 --> 01:09:48.359 That's really bad at it, and the neurons are firing a lot. 01:09:48.359 --> 01:09:50.100 It's sort of facetious, but sort of not. 01:09:50.100 --> 01:09:51.870 And it's probably not the right account, 01:09:51.870 --> 01:09:54.180 but it is an important reminder that we actually 01:09:54.180 --> 01:09:57.240 don't know what actual kind of neural activity 01:09:57.240 --> 01:10:00.660 is driving those things and whether it's 01:10:00.660 --> 01:10:03.258 excitatory or inhibitory, absolutely. 01:10:03.258 --> 01:10:04.050 Hang on one second. 01:10:04.050 --> 01:10:05.580 I feel like there was another part of what you said 01:10:05.580 --> 01:10:07.010 that I was going to engage on. 01:10:07.010 --> 01:10:09.120 AUDIENCE: No, It feels like somehow, possibly, 01:10:09.120 --> 01:10:11.910 connected to the perception [INAUDIBLE].. 01:10:11.910 --> 01:10:13.990 NANCY KANWISHER: Yeah. 01:10:13.990 --> 01:10:15.040 Yeah, possibly. 01:10:15.040 --> 01:10:17.800 We'd have to work it out. 01:10:17.800 --> 01:10:21.423 AUDIENCE: In one of the lectures [INAUDIBLE],, 01:10:21.423 --> 01:10:22.340 NANCY KANWISHER: Yeah. 01:10:22.340 --> 01:10:28.290 AUDIENCE: And then, [INAUDIBLE] 01:10:28.290 --> 01:10:29.165 NANCY KANWISHER: Yes. 01:10:29.165 --> 01:10:30.855 AUDIENCE: [INAUDIBLE] 01:10:30.855 --> 01:10:31.730 NANCY KANWISHER: Yes. 01:10:31.730 --> 01:10:32.940 AUDIENCE: Then, I'm a bit confused, 01:10:32.940 --> 01:10:35.720 because, like, you said before, almost like all the wiring is 01:10:35.720 --> 01:10:36.980 [INAUDIBLE]. 01:10:36.980 --> 01:10:38.750 NANCY KANWISHER: OK, long-range wiring. 01:10:38.750 --> 01:10:39.410 AUDIENCE: Oh. 01:10:39.410 --> 01:10:40.243 NANCY KANWISHER: OK? 01:10:40.243 --> 01:10:42.260 Which is very different than all the circuits 01:10:42.260 --> 01:10:44.330 that live in each little patch of cortex. 01:10:44.330 --> 01:10:47.840 Remember, I showed you this big change 01:10:47.840 --> 01:10:53.180 in the complexity of neurons and the number of connections. 01:10:53.180 --> 01:10:54.950 Oops, looks like we've lost it now. 01:11:00.590 --> 01:11:04.130 So they're changing a lot within each patch of cortex, right? 01:11:04.130 --> 01:11:06.530 So those local circuits that are doing computations 01:11:06.530 --> 01:11:09.590 are surely changing a lot over the first couple of years. 01:11:09.590 --> 01:11:11.960 It's just the long-range connections between that patch 01:11:11.960 --> 01:11:13.490 and some remote region-- 01:11:13.490 --> 01:11:17.390 where it gets its inputs and where it sends its outputs to. 01:11:17.390 --> 01:11:18.290 But hang on a second. 01:11:18.290 --> 01:11:22.043 You asked something-- there's also very interesting stuff 01:11:22.043 --> 01:11:23.210 about the other race effect. 01:11:23.210 --> 01:11:26.060 I did mention that a month ago or so, didn't I? 01:11:26.060 --> 01:11:30.110 Which is another version of this perceptual narrowing. 01:11:30.110 --> 01:11:33.415 And in fact, a friend of mine who's a great face researcher 01:11:33.415 --> 01:11:34.790 has not yet published this paper, 01:11:34.790 --> 01:11:35.957 but she found the following. 01:11:35.957 --> 01:11:38.780 Totally, that's right-- you mentioned the adoption studies. 01:11:38.780 --> 01:11:40.845 So what she has done is ask-- 01:11:40.845 --> 01:11:42.470 did I tell you guys about this already? 01:11:42.470 --> 01:11:43.850 I feel like I did, but maybe not. 01:11:43.850 --> 01:11:48.360 Anyway, so what you find is that people are-- 01:11:48.360 --> 01:11:49.670 they all look alike. 01:11:49.670 --> 01:11:52.340 Whoever they are, if you've seen fewer of them 01:11:52.340 --> 01:11:55.580 than whoever we are, you are less 01:11:55.580 --> 01:11:56.750 good at discriminating them. 01:11:56.750 --> 01:11:57.920 That's just what it is. 01:11:57.920 --> 01:12:02.120 But so Elinor McKone asked if there's 01:12:02.120 --> 01:12:05.000 a developmental timeline for getting your way out 01:12:05.000 --> 01:12:06.960 of the other race effect. 01:12:06.960 --> 01:12:09.380 And so what she did was-- she's in Australia, 01:12:09.380 --> 01:12:11.270 and she got various communities of people 01:12:11.270 --> 01:12:14.210 who move from dominant racial composition 01:12:14.210 --> 01:12:16.700 x to dominant racial composition y 01:12:16.700 --> 01:12:20.880 and who made that move at different ages. 01:12:20.880 --> 01:12:22.790 And so what she finds is that, actually, 01:12:22.790 --> 01:12:25.580 much like learning the phonemes of a language-- which, 01:12:25.580 --> 01:12:27.556 even if you-- 01:12:27.556 --> 01:12:29.202 hey, let me back up a second. 01:12:29.202 --> 01:12:31.160 I said that with phonemes, you can discriminate 01:12:31.160 --> 01:12:33.758 all those phonemes of all the world's languages at birth, 01:12:33.758 --> 01:12:35.300 and by six months, you've thrown away 01:12:35.300 --> 01:12:36.802 the abilities for all the phonemes 01:12:36.802 --> 01:12:37.760 you can't discriminate. 01:12:37.760 --> 01:12:41.480 However, if you then go learn a foreign language sometime 01:12:41.480 --> 01:12:44.360 between six months and, say, 12, you 01:12:44.360 --> 01:12:45.540 can become a native speaker. 01:12:45.540 --> 01:12:46.880 So you can learn them back, right? 01:12:46.880 --> 01:12:48.338 So there's another window-- it gets 01:12:48.338 --> 01:12:51.950 narrowed-- but you still have a window to learn them back, OK? 01:12:51.950 --> 01:12:55.460 After you're like 12, 15, whatever, forget it. 01:12:55.460 --> 01:12:57.380 You won't be a native speaker, right? 01:12:57.380 --> 01:12:59.012 Same deal with the other race effect. 01:12:59.012 --> 01:13:01.220 This is exactly what McKone found with the other race 01:13:01.220 --> 01:13:02.240 effect. 01:13:02.240 --> 01:13:08.330 People who moved to a different dominant racial community 01:13:08.330 --> 01:13:11.420 learned the ability to natively discriminate people 01:13:11.420 --> 01:13:15.020 in that other race if they moved before age 12. 01:13:15.020 --> 01:13:17.277 So it really seems like there's some general ability. 01:13:17.277 --> 01:13:18.860 Oh, I remember David's other question. 01:13:18.860 --> 01:13:20.130 Why does this make sense? 01:13:20.130 --> 01:13:21.797 I don't know exactly why it makes sense, 01:13:21.797 --> 01:13:26.570 but certainly, neural activity is expensive metabolically, 01:13:26.570 --> 01:13:28.310 and we don't want to make discriminations 01:13:28.310 --> 01:13:29.750 we don't have to. 01:13:29.750 --> 01:13:32.990 And so it can be just that the nervous system is learning 01:13:32.990 --> 01:13:34.790 what kinds of discriminations it needs 01:13:34.790 --> 01:13:37.487 to make in its environment and what kind it doesn't, right? 01:13:37.487 --> 01:13:39.320 And with the case of phonemes, it's actually 01:13:39.320 --> 01:13:41.360 part of what you're doing in speech perception, 01:13:41.360 --> 01:13:45.110 is you want to know, every time I say "ba," 01:13:45.110 --> 01:13:47.130 it sounds different in all different contexts. 01:13:47.130 --> 01:13:50.030 And so part of the essence of the difficulty in speech 01:13:50.030 --> 01:13:52.520 recognition is understanding that all those different "ba"s 01:13:52.520 --> 01:13:54.980 are the same sound, right? 01:13:54.980 --> 01:13:57.650 And so part of what perceptual narrowing might be doing 01:13:57.650 --> 01:13:59.210 is saying all those things-- 01:13:59.210 --> 01:14:02.180 "da," "ta," whatever it is in Hindi-- 01:14:02.180 --> 01:14:04.738 those are all going to count as the same thing. 01:14:04.738 --> 01:14:06.530 And that's going to help you process speech 01:14:06.530 --> 01:14:09.140 in your native language but hinder when you try 01:14:09.140 --> 01:14:12.630 to learn a foreign language. 01:14:12.630 --> 01:14:13.130 Yeah? 01:14:13.130 --> 01:14:14.630 AUDIENCE: So something I'm wondering 01:14:14.630 --> 01:14:18.620 with perceptual narrowing is how general like the starting point 01:14:18.620 --> 01:14:19.120 is. 01:14:19.120 --> 01:14:21.287 So I'm basically wondering-- because in the studies, 01:14:21.287 --> 01:14:22.920 they compared human and monkey faces. 01:14:22.920 --> 01:14:23.300 NANCY KANWISHER: Yeah. 01:14:23.300 --> 01:14:24.883 AUDIENCE: And I'm wondering if there's 01:14:24.883 --> 01:14:28.110 any correlation with how similar the DNA, 01:14:28.110 --> 01:14:31.310 like how they're able to discriminate between the faces. 01:14:31.310 --> 01:14:33.800 So whether that's different types of monkeys, 01:14:33.800 --> 01:14:35.300 or different animals-- 01:14:35.300 --> 01:14:37.092 NANCY KANWISHER: I'm not getting it, right? 01:14:37.092 --> 01:14:39.650 Early on, you can discriminate both, right? 01:14:39.650 --> 01:14:40.860 So what's the question? 01:14:40.860 --> 01:14:43.220 AUDIENCE: So I'm wondering what other animals can they 01:14:43.220 --> 01:14:44.090 discriminate, and what-- 01:14:44.090 --> 01:14:44.750 NANCY KANWISHER: I see, I see. 01:14:44.750 --> 01:14:45.710 How far does it go? 01:14:45.710 --> 01:14:47.430 Yeah, good question. 01:14:47.430 --> 01:14:50.750 I don't know that anybody has asked little kids if they 01:14:50.750 --> 01:14:56.030 can discriminate other kinds of faces other than monkey faces. 01:14:56.030 --> 01:14:58.970 I'm sure there's some limit to it-- like fish faces? 01:14:58.970 --> 01:15:03.410 Probably, I don't know, yeah. 01:15:03.410 --> 01:15:05.877 But there's also, actually, in terms of that extended-- 01:15:05.877 --> 01:15:07.460 I don't know the answer to that, yeah. 01:15:07.460 --> 01:15:09.080 There's going to be some limit. 01:15:09.080 --> 01:15:14.240 But in terms of the question of how long 01:15:14.240 --> 01:15:17.030 can you relearn those abilities or maintain them, 01:15:17.030 --> 01:15:19.910 it's not like perceptual narrowing 01:15:19.910 --> 01:15:22.920 is going to happen at six months automatically. 01:15:22.920 --> 01:15:26.090 So if you manipulate it-- so the studies on humans, 01:15:26.090 --> 01:15:27.135 if you send-- 01:15:27.135 --> 01:15:28.760 I feel like I said this in here before, 01:15:28.760 --> 01:15:30.740 but it must have been somewhere else-- 01:15:30.740 --> 01:15:33.830 if you send parents home with books 01:15:33.830 --> 01:15:37.610 with monkey pictures in them, parents of six-month-olds, 01:15:37.610 --> 01:15:39.740 and you say, look, every night, go 01:15:39.740 --> 01:15:42.410 through the book with your kids and say, there's Monkey Joe, 01:15:42.410 --> 01:15:44.060 and there's Monkey Bob, and there's 01:15:44.060 --> 01:15:47.870 Monkey Whoever with your kids, and you 01:15:47.870 --> 01:15:50.240 have them do that from age six months to 12 months, 01:15:50.240 --> 01:15:52.520 they don't perceptually narrow, because they continue 01:15:52.520 --> 01:15:55.460 to get that experience, right? 01:15:55.460 --> 01:15:58.580 Interestingly, if the parents go home and just say, 01:15:58.580 --> 01:16:02.420 look, look, that doesn't do it. 01:16:02.420 --> 01:16:05.090 You have to give them some social cue that is essentially 01:16:05.090 --> 01:16:07.940 saying, this thing is different from that thing. 01:16:07.940 --> 01:16:09.560 And if you do that with an infant, 01:16:09.560 --> 01:16:11.768 even when they don't really understand language much, 01:16:11.768 --> 01:16:14.065 they get that cue, and they learn to discriminate-- 01:16:14.065 --> 01:16:16.565 or they maintain their ability to discriminate monkey faces. 01:16:19.520 --> 01:16:20.020 Yeah? 01:16:20.020 --> 01:16:21.562 AUDIENCE: Does that hold up even when 01:16:21.562 --> 01:16:23.492 they're past the 12 months old? 01:16:23.492 --> 01:16:24.950 NANCY KANWISHER: Well, I'm guessing 01:16:24.950 --> 01:16:29.090 it will be just like the case that McKone showed 01:16:29.090 --> 01:16:31.240 with other race effects, right? 01:16:31.240 --> 01:16:32.990 I'm guessing the other species effect will 01:16:32.990 --> 01:16:35.870 be like the other race effect in that 01:16:35.870 --> 01:16:38.300 if you, say, start working in a monkey lab 01:16:38.300 --> 01:16:40.670 when you're eight years old-- 01:16:40.670 --> 01:16:43.190 that would be weird, but you could-- 01:16:43.190 --> 01:16:44.960 or you-- I don't know, whatever. 01:16:44.960 --> 01:16:48.410 Anyway, that you would be able to relearn it on the same time 01:16:48.410 --> 01:16:51.440 scale that you would relearn-- 01:16:51.440 --> 01:16:54.800 relearn, or learn for the first time, previously 01:16:54.800 --> 01:16:56.630 unfamiliar races of faces. 01:16:56.630 --> 01:17:00.270 But maybe those are slightly different timelines. 01:17:00.270 --> 01:17:01.320 Yeah? 01:17:01.320 --> 01:17:03.120 AUDIENCE: Could you do something similar 01:17:03.120 --> 01:17:05.370 with the monkey faces, but with phonemes 01:17:05.370 --> 01:17:06.623 in different languages? 01:17:06.623 --> 01:17:08.040 NANCY KANWISHER: I'm sure you can, 01:17:08.040 --> 01:17:09.600 and I'm sure that has been done, but I 01:17:09.600 --> 01:17:10.725 don't know that literature. 01:17:10.725 --> 01:17:11.260 Yeah. 01:17:11.260 --> 01:17:12.630 Yeah, you mean like keep-- 01:17:12.630 --> 01:17:13.290 well, OK. 01:17:13.290 --> 01:17:15.480 I mean, it essentially does get done, right? 01:17:15.480 --> 01:17:20.680 So kids who stay in environments-- 01:17:20.680 --> 01:17:21.750 let me think about this. 01:17:21.750 --> 01:17:24.660 Well, certainly, an infant who's being 01:17:24.660 --> 01:17:26.460 raised in a bilingual environment 01:17:26.460 --> 01:17:29.130 will maintain their ability to discriminate those phonemes 01:17:29.130 --> 01:17:32.348 from any of the languages they hear, right? 01:17:32.348 --> 01:17:34.890 AUDIENCE: So you're saying, with the monkeys thing, some kind 01:17:34.890 --> 01:17:37.440 of social cue to know that-- 01:17:37.440 --> 01:17:39.240 NANCY KANWISHER: I suspect that's true. 01:17:39.240 --> 01:17:40.948 I don't know this literature well enough. 01:17:40.948 --> 01:17:43.317 I do know-- yeah, actually, it's coming back dimly. 01:17:43.317 --> 01:17:44.400 Heather, do you know this? 01:17:44.400 --> 01:17:45.000 Janet Werker 01:17:45.000 --> 01:17:46.740 AUDIENCE: [INAUDIBLE]. 01:17:46.740 --> 01:17:48.240 NANCY KANWISHER: OK, so Janet Werker 01:17:48.240 --> 01:17:51.810 is this amazing infant phoneme perception researcher. 01:17:51.810 --> 01:17:55.650 And I'm pretty sure that if you present infants 01:17:55.650 --> 01:17:57.630 with just like a TV in the background 01:17:57.630 --> 01:18:01.200 with a foreign language, even if the infant doesn't have much 01:18:01.200 --> 01:18:03.270 else to do, that's not enough. 01:18:03.270 --> 01:18:05.580 And you need to look at them, and engage with them, 01:18:05.580 --> 01:18:09.632 and speak mother-ese-- like, hey, infant, blah, blah, right? 01:18:09.632 --> 01:18:12.090 I think you need to do all of that for them to maintain it, 01:18:12.090 --> 01:18:12.668 but I'm-- 01:18:12.668 --> 01:18:13.960 AUDIENCE: Yeah, that's correct. 01:18:13.960 --> 01:18:15.668 I think there also has to be interaction. 01:18:15.668 --> 01:18:18.420 They can't also just be watching the [INAUDIBLE].. 01:18:18.420 --> 01:18:20.220 It has to be slightly [INAUDIBLE] 01:18:20.220 --> 01:18:21.340 reciprocal [INAUDIBLE]. 01:18:21.340 --> 01:18:23.460 AUDIENCE: And the fact that [INAUDIBLE].. 01:18:26.108 --> 01:18:27.400 NANCY KANWISHER: Correct, yeah. 01:18:27.400 --> 01:18:29.516 AUDIENCE: So even if it's not just [INAUDIBLE],, 01:18:29.516 --> 01:18:30.752 it has to be [INAUDIBLE]. 01:18:30.752 --> 01:18:32.210 NANCY KANWISHER: It has to be what? 01:18:32.210 --> 01:18:33.918 AUDIENCE: It has to be like [INAUDIBLE].. 01:18:33.918 --> 01:18:35.390 It can't be [INAUDIBLE]. 01:18:35.390 --> 01:18:38.190 AUDIENCE: Yeah, which makes me of [INAUDIBLE] or something-- 01:18:38.190 --> 01:18:40.490 like if you interact in different ways, [INAUDIBLE].. 01:18:43.040 --> 01:18:44.430 NANCY KANWISHER: Cool, yeah? 01:18:44.430 --> 01:18:47.270 AUDIENCE: Yeah, I have a question about how long 01:18:47.270 --> 01:18:49.286 that [INAUDIBLE] lasts. 01:18:49.286 --> 01:18:50.930 If someone spoke a foreign language 01:18:50.930 --> 01:18:53.220 when they were younger, then moved somewhere else 01:18:53.220 --> 01:18:56.120 or were adopted and then stopped speaking the language, 01:18:56.120 --> 01:19:03.420 [INAUDIBLE],, could they sort of be [INAUDIBLE]?? 01:19:03.420 --> 01:19:04.670 NANCY KANWISHER: I don't know. 01:19:04.670 --> 01:19:06.253 I'm sure there's a literature on that. 01:19:06.253 --> 01:19:07.970 You don't know that, Dana, do you? 01:19:07.970 --> 01:19:11.090 Sorry, like so you're raised bilingual, 01:19:11.090 --> 01:19:13.580 and then you stop having the experience early 01:19:13.580 --> 01:19:16.100 on from your second language, and then 01:19:16.100 --> 01:19:18.860 you're re-exposed later at age eight? 01:19:18.860 --> 01:19:19.850 AUDIENCE: [INAUDIBLE]. 01:19:19.850 --> 01:19:21.640 AUDIENCE: Yeah, you still have the-- 01:19:21.640 --> 01:19:23.140 yeah, you maintain the [INAUDIBLE].. 01:19:23.140 --> 01:19:24.100 AUDIENCE: Yeah, like after-- 01:19:24.100 --> 01:19:25.475 NANCY KANWISHER: Well, but wait-- 01:19:25.475 --> 01:19:27.935 AUDIENCE: But you're not able to speak the language, right? 01:19:27.935 --> 01:19:28.560 AUDIENCE: Yeah. 01:19:28.560 --> 01:19:29.840 AUDIENCE: But you still [INAUDIBLE].. 01:19:29.840 --> 01:19:30.290 AUDIENCE: But I guess you-- 01:19:30.290 --> 01:19:31.665 NANCY KANWISHER: But then, that's 01:19:31.665 --> 01:19:33.565 not consistent with perceptual narrowing. 01:19:33.565 --> 01:19:35.690 AUDIENCE: If you're exposed to it before two years? 01:19:35.690 --> 01:19:36.170 AUDIENCE: Yeah. 01:19:36.170 --> 01:19:36.260 NANCY KANWISHER: Yeah. 01:19:36.260 --> 01:19:37.635 AUDIENCE: And then you move away? 01:19:37.635 --> 01:19:39.010 NANCY KANWISHER: Well, if it goes 01:19:39.010 --> 01:19:40.880 beyond that six-month thing, yeah, OK. 01:19:40.880 --> 01:19:42.620 AUDIENCE: I think that's the case, yeah. 01:19:42.620 --> 01:19:44.287 You might not have the higher structure, 01:19:44.287 --> 01:19:48.170 but if you like you the syntax and some vocabulary, 01:19:48.170 --> 01:19:51.170 you'll have a better accent than someone who did not 01:19:51.170 --> 01:19:53.090 have that early experience, might not 01:19:53.090 --> 01:19:55.990 be able to differentiate [INAUDIBLE].. 01:19:55.990 --> 01:19:56.650 But-- 01:19:56.650 --> 01:19:57.942 AUDIENCE: You just [INAUDIBLE]. 01:20:00.460 --> 01:20:02.937 AUDIENCE: [INAUDIBLE],, I think that's correct. 01:20:02.937 --> 01:20:04.020 NANCY KANWISHER: OK, good. 01:20:04.020 --> 01:20:04.770 One more question. 01:20:04.770 --> 01:20:05.440 Josh? 01:20:05.440 --> 01:20:07.023 AUDIENCE: So do we know of cases where 01:20:07.023 --> 01:20:12.000 there's [INAUDIBLE] a mismatch between [INAUDIBLE] sort 01:20:12.000 --> 01:20:13.300 of information? 01:20:13.300 --> 01:20:13.800 Like-- 01:20:13.800 --> 01:20:14.460 NANCY KANWISHER: Like this? 01:20:14.460 --> 01:20:16.350 AUDIENCE: Yeah, like-- with this property 01:20:16.350 --> 01:20:18.720 in some of the domain of some of the [INAUDIBLE].. 01:20:18.720 --> 01:20:20.495 Basically be [INAUDIBLE]. 01:20:20.495 --> 01:20:21.870 NANCY KANWISHER: Oh, god, I don't 01:20:21.870 --> 01:20:25.290 have my dictionary of knowledge filed that way 01:20:25.290 --> 01:20:27.090 so I can pull up an instance of that, 01:20:27.090 --> 01:20:29.115 but I'm sure there are loads of those. 01:20:29.115 --> 01:20:30.153 AUDIENCE: [INAUDIBLE]. 01:20:30.153 --> 01:20:32.070 NANCY KANWISHER: Yeah, well, because when we-- 01:20:32.070 --> 01:20:34.320 because we're making all these assumptions about which 01:20:34.320 --> 01:20:37.108 behavioral ability is subserved by some particular activation 01:20:37.108 --> 01:20:37.650 in the brain. 01:20:37.650 --> 01:20:40.238 And mostly, we don't know, right? 01:20:40.238 --> 01:20:42.030 We know when we have the rare opportunities 01:20:42.030 --> 01:20:42.990 to do causal tests. 01:20:42.990 --> 01:20:44.850 We have a better idea that that system 01:20:44.850 --> 01:20:48.750 is at least causally involved in that behavioral ability. 01:20:48.750 --> 01:20:53.890 But yeah, often, those links are much looser than we'd like. 01:20:53.890 --> 01:20:56.550 All right, see you guys Wednesday.