WEBVTT 00:00:00.040 --> 00:00:02.460 The following content is provided under a Creative 00:00:02.460 --> 00:00:03.870 Commons license. 00:00:03.870 --> 00:00:06.910 Your support will help MIT OpenCourseWare continue to 00:00:06.910 --> 00:00:10.560 offer high quality educational resources for free. 00:00:10.560 --> 00:00:13.460 To make a donation or view additional materials from 00:00:13.460 --> 00:00:19.280 hundreds of MIT courses, visit MIT OpenCourseWare at 00:00:19.280 --> 00:00:20.530 ocw.mit.edu. 00:00:27.460 --> 00:00:28.710 PROFESSOR: Good afternoon. 00:00:33.908 --> 00:00:38.610 So we've come to a topic that I think feels to us like 00:00:38.610 --> 00:00:42.870 intuitively almost the core of psychology might be about is 00:00:42.870 --> 00:00:43.348 personality. 00:00:43.348 --> 00:00:47.172 Why are some things easy for us and hard for us? 00:00:47.172 --> 00:00:48.810 Why do we like some things or something else? 00:00:48.810 --> 00:00:52.824 Why do people around us behave kindly or rudely, supportively 00:00:52.824 --> 00:00:55.184 or loyally or whatever? 00:00:55.184 --> 00:00:58.870 What can we understand about personality scientifically? 00:00:58.870 --> 00:01:02.382 So how do psychologists try to study it in a somewhat 00:01:02.382 --> 00:01:04.379 systematic fashion? 00:01:04.379 --> 00:01:07.970 Some key concepts that we're finding are traits, states, 00:01:07.970 --> 00:01:09.630 and context. 00:01:09.630 --> 00:01:10.180 Traits-- 00:01:10.180 --> 00:01:11.170 I'll come to these. 00:01:11.170 --> 00:01:14.750 And then finally some brain correlates for personality. 00:01:14.750 --> 00:01:17.130 So I love this quote, because I think it's about 00:01:17.130 --> 00:01:19.980 individuality, which says, every person is in certain 00:01:19.980 --> 00:01:21.930 respects like all other people-- 00:01:21.930 --> 00:01:22.780 and we think that's true. 00:01:22.780 --> 00:01:27.190 There's something deeply similar among all humans, also 00:01:27.190 --> 00:01:29.700 about psychology, also about our brains. 00:01:29.700 --> 00:01:32.550 Like some other people, that is, there's dimensions of 00:01:32.550 --> 00:01:35.450 individuality, or like some other people, like if we're a 00:01:35.450 --> 00:01:38.740 male or female, if we're this age or that age, this culture 00:01:38.740 --> 00:01:42.180 or that culture, like math or don't like math, like vanilla 00:01:42.180 --> 00:01:44.080 ice cream or don't like ice cream. 00:01:44.080 --> 00:01:47.740 And then finally, we come down to the unique set of things 00:01:47.740 --> 00:01:49.130 that make you you. 00:01:49.130 --> 00:01:51.920 And that's very hard to study, the unique things 00:01:51.920 --> 00:01:52.510 that make you you. 00:01:52.510 --> 00:01:55.770 But the second level, dimensions of individuality, 00:01:55.770 --> 00:01:57.520 we can study in personality. 00:01:57.520 --> 00:01:59.480 It's obviously a big one that we feel in our own 00:01:59.480 --> 00:02:02.460 lives and around us. 00:02:02.460 --> 00:02:08.889 So this is the old original "Star Trek." Like many 00:02:08.889 --> 00:02:12.660 programs, or in TV series, it plays out really in part-- 00:02:12.660 --> 00:02:15.780 they go from galaxy to galaxy and struggle with various 00:02:15.780 --> 00:02:17.330 opponents, civilizations. 00:02:17.330 --> 00:02:19.520 But it almost always comes down to a 00:02:19.520 --> 00:02:20.820 personality thing, right? 00:02:20.820 --> 00:02:23.450 The Captain Kirk who wants to be aggressive and charge in 00:02:23.450 --> 00:02:27.300 there and do something very emotional, Spock who's the 00:02:27.300 --> 00:02:31.920 pure rational machine, and McCoy who represents a sort of 00:02:31.920 --> 00:02:33.930 humane touch, as opposed to the rational thought. 00:02:33.930 --> 00:02:36.260 And somewhere in between is the man who has to pick the 00:02:36.260 --> 00:02:37.650 action to command the ship, right? 00:02:37.650 --> 00:02:40.490 So every show plays out with him asking him 00:02:40.490 --> 00:02:41.560 to be human, right? 00:02:41.560 --> 00:02:46.060 And him asking him to be rational, and him killing 00:02:46.060 --> 00:02:47.690 somebody who's trouble making. 00:02:47.690 --> 00:02:49.710 OK. 00:02:49.710 --> 00:02:50.860 So what do we mean by personality? 00:02:50.860 --> 00:02:52.710 A set of behavioral, emotional, and cognitive 00:02:52.710 --> 00:02:54.860 tendencies that people display over time. 00:02:54.860 --> 00:02:57.070 When we talk about personality, we really mean 00:02:57.070 --> 00:02:59.140 something that we think is consistent in ourselves or in 00:02:59.140 --> 00:02:59.750 other people. 00:02:59.750 --> 00:03:01.700 It's that somebody is shy, somebody's 00:03:01.700 --> 00:03:04.120 helpful, somebody's rude. 00:03:04.120 --> 00:03:07.340 And across situations, not just one place, one time, but 00:03:07.340 --> 00:03:09.390 pretty regularly. 00:03:09.390 --> 00:03:12.130 And that varies across people. 00:03:12.130 --> 00:03:14.220 That distinguishes them from one to another. 00:03:14.220 --> 00:03:15.880 Something that's kind of-- 00:03:15.880 --> 00:03:20.130 there's some similarities, but people vary in this. 00:03:20.130 --> 00:03:22.650 And so when people think about this, they think in three 00:03:22.650 --> 00:03:23.970 categories as they conceptualize it. 00:03:23.970 --> 00:03:24.690 One is traits. 00:03:24.690 --> 00:03:29.380 By trait we mean something that's in you that's constant 00:03:29.380 --> 00:03:31.610 across situations and times. 00:03:31.610 --> 00:03:33.540 But we also think of it as a continuum. 00:03:33.540 --> 00:03:36.730 So for example, we talk about introversion/extroversion or 00:03:36.730 --> 00:03:39.190 outgoingness and shyness. 00:03:39.190 --> 00:03:41.780 It's not that everybody's one or the other. 00:03:41.780 --> 00:03:45.850 Along that path from being extremely shy to extremely 00:03:45.850 --> 00:03:49.550 outgoing, many of us are somewhere in between. 00:03:49.550 --> 00:03:51.550 And then we can talk about states, how we are 00:03:51.550 --> 00:03:52.800 temporarily. 00:03:52.800 --> 00:03:56.140 How do we feel, excited, afraid, that kind of stuff. 00:03:56.140 --> 00:03:59.460 And then situations we're in, because they're specific at 00:03:59.460 --> 00:04:01.700 times and places, and that influences us. 00:04:01.700 --> 00:04:03.740 We're fearful, we're happy, we're looking forward to 00:04:03.740 --> 00:04:05.880 something, we're not looking forward to something. 00:04:05.880 --> 00:04:08.870 So these are different pieces that might end up in how we 00:04:08.870 --> 00:04:13.600 feel inside and how we act on the world. 00:04:13.600 --> 00:04:16.140 So here's a very funny thing, because it's a very different 00:04:16.140 --> 00:04:18.140 line of research than practically anything else 00:04:18.140 --> 00:04:18.750 that's out there. 00:04:18.750 --> 00:04:23.150 Very active, because we're so curious about personality. 00:04:23.150 --> 00:04:25.190 Here's how people have basically approached it. 00:04:25.190 --> 00:04:28.750 Not everybody, but the main line scientific perspective. 00:04:28.750 --> 00:04:31.800 They looked in the dictionary, originally in the 1930s, for 00:04:31.800 --> 00:04:34.270 this line of work, and they said, let's look at all the 00:04:34.270 --> 00:04:38.420 adjectives in the dictionary that we think might describe 00:04:38.420 --> 00:04:42.010 personality in some sense. 00:04:42.010 --> 00:04:46.240 They found nearly 18,000 words in the dictionaries that 00:04:46.240 --> 00:04:49.420 seemed to be adjectives for describing people, and 00:04:49.420 --> 00:04:51.420 something that might be about personality. 00:04:51.420 --> 00:04:54.730 Whether you're affable, or amiable, congenial, convivial, 00:04:54.730 --> 00:04:56.510 cordial, friendly, genial, sociable, welcoming. 00:04:56.510 --> 00:04:59.670 These are all synonyms, right? 00:04:59.670 --> 00:05:03.010 They all mean roughly the same thing, we think. 00:05:03.010 --> 00:05:07.250 But they found 18,000 terms there because we think a lot 00:05:07.250 --> 00:05:09.050 about other people, and talk a lot about other people, and 00:05:09.050 --> 00:05:10.870 other people are interesting to us. 00:05:10.870 --> 00:05:14.610 And as I said, we're not going to study 18,000 dimensions of 00:05:14.610 --> 00:05:16.330 personality, especially when lots of them 00:05:16.330 --> 00:05:17.910 overlap like this. 00:05:17.910 --> 00:05:21.100 So what we're going to do is see, are there some underlying 00:05:21.100 --> 00:05:24.020 traits, a manageable set of personality traits or 00:05:24.020 --> 00:05:28.110 dimensions, that many of these 18,000 adjectives sort 00:05:28.110 --> 00:05:30.050 of boil down to. 00:05:30.050 --> 00:05:33.160 So a manageable set of personality dimensions. 00:05:33.160 --> 00:05:35.780 So how do people measure personality in some way? 00:05:35.780 --> 00:05:38.380 And for those of us who like to measure things by 00:05:38.380 --> 00:05:41.090 behavior-- you do a test, or you push a button, or we 00:05:41.090 --> 00:05:42.180 measure your brain-- 00:05:42.180 --> 00:05:45.160 personality research is always funny, because the bulk of it 00:05:45.160 --> 00:05:48.230 is people's self report about themselves. 00:05:48.230 --> 00:05:51.930 And about the last thing most of us in psychology trust is 00:05:51.930 --> 00:05:54.050 people's reports about themselves. 00:05:54.050 --> 00:05:55.840 And what we think is-- 00:05:55.840 --> 00:05:58.260 for many reasons that we can talk about a little bit-- 00:05:58.260 --> 00:06:03.010 what we think is that people, when they fill out a piece of 00:06:03.010 --> 00:06:05.850 paper describing themselves, they start to have all kinds 00:06:05.850 --> 00:06:08.540 of thoughts like, OK, I'm outgoing, but compared to who? 00:06:13.230 --> 00:06:15.630 Do I want to fill this out like I really like to think 00:06:15.630 --> 00:06:18.500 about myself, or how I think I really am, or am I sometimes 00:06:18.500 --> 00:06:20.330 this way and sometimes that way, which 00:06:20.330 --> 00:06:21.140 is the right answer. 00:06:21.140 --> 00:06:21.560 OK? 00:06:21.560 --> 00:06:24.460 So all these things bother us as researchers, but we don't 00:06:24.460 --> 00:06:27.020 have a more direct path towards personality. 00:06:27.020 --> 00:06:29.490 So we can interview people about their personality. 00:06:29.490 --> 00:06:30.300 We can observe-- 00:06:30.300 --> 00:06:32.500 I'll talk about some studies that involve observation. 00:06:32.500 --> 00:06:35.150 But by far the dominant mode of collecting somewhat 00:06:35.150 --> 00:06:37.810 quantitative data about personality are questionnaires 00:06:37.810 --> 00:06:39.720 of the kind you just got handed out to you. 00:06:39.720 --> 00:06:41.370 Thank you, Tyler. 00:06:41.370 --> 00:06:43.750 And the most famous one of all, which you have in your 00:06:43.750 --> 00:06:47.310 hands, is the so-called big five personality dimensions. 00:06:47.310 --> 00:06:50.400 There's many other aspects of personality-- we'll talk about 00:06:50.400 --> 00:06:52.370 that-- but this is the most famous one. 00:06:52.370 --> 00:06:55.060 And it was derived in some sense objectively and 00:06:55.060 --> 00:06:58.930 empirically from factor analysis like this. 00:06:58.930 --> 00:07:01.680 What they said is we have this huge number of terms, but many 00:07:01.680 --> 00:07:04.740 of them are either very similar to one another, or 00:07:04.740 --> 00:07:06.540 what we might call anti-correlative, they're sort 00:07:06.540 --> 00:07:07.650 of opposites. 00:07:07.650 --> 00:07:11.680 So for example, if a person is rude, are we also likely to 00:07:11.680 --> 00:07:13.520 think of them as kind? 00:07:13.520 --> 00:07:14.860 Now you could have-- 00:07:14.860 --> 00:07:18.490 there's many movies of the rude senior citizen who turns 00:07:18.490 --> 00:07:21.620 out to have a heart of gold underneath, right? 00:07:21.620 --> 00:07:24.110 But in general, if you say this person's rude, usually 00:07:24.110 --> 00:07:25.990 they'll go, and they're so kind, right? 00:07:25.990 --> 00:07:28.680 We think of them as sort of opposites in personality. 00:07:28.680 --> 00:07:31.040 If somebody's dependable or carefree. 00:07:31.040 --> 00:07:32.730 Now, maybe you know somebody who's both dependable and 00:07:32.730 --> 00:07:35.260 carefree, but we tend to think carefree people are not so 00:07:35.260 --> 00:07:35.900 dependable. 00:07:35.900 --> 00:07:38.280 They can be delightful dependable people. 00:07:38.280 --> 00:07:41.840 But now, rude-- you can be dependable and rude or 00:07:41.840 --> 00:07:43.560 dependable and polite, right? 00:07:43.560 --> 00:07:45.960 OK, so get a feeling of that. 00:07:45.960 --> 00:07:50.710 So they have people fill out tons of pieces of paper saying 00:07:50.710 --> 00:07:53.790 how do they feel these factors describe them. 00:07:53.790 --> 00:07:56.960 And they start out with this huge universe of terms, and 00:07:56.960 --> 00:07:59.600 then they try to boil it down, and boil it down, and boil it 00:07:59.600 --> 00:08:01.040 down, by looking at-- 00:08:01.040 --> 00:08:02.200 Oh, this doesn't show up very well, does it? 00:08:02.200 --> 00:08:03.560 Oh, well. 00:08:03.560 --> 00:08:04.260 Correlations-- 00:08:04.260 --> 00:08:05.640 you have the notes. 00:08:05.640 --> 00:08:11.150 So you can guess without being able to see, you can guess-- 00:08:11.150 --> 00:08:12.710 let's pick two things. 00:08:12.710 --> 00:08:18.900 If I pick the adjectives carefree and dependable, kind 00:08:18.900 --> 00:08:21.650 of go together or not go together? 00:08:21.650 --> 00:08:24.500 Doesn't tend to go together in people describing themselves. 00:08:24.500 --> 00:08:27.940 How about hard working and dependable? 00:08:27.940 --> 00:08:30.370 Kind of goes together. 00:08:30.370 --> 00:08:33.419 So they said, we can take a lot of these adjectives and 00:08:33.419 --> 00:08:36.409 say piles of them go in one area, well, we'll just pick a 00:08:36.409 --> 00:08:38.409 few words to describe that dimension. 00:08:38.409 --> 00:08:40.400 Piles of them go in another area. 00:08:40.400 --> 00:08:46.090 And they boil it down basically by factor analysis, 00:08:46.090 --> 00:08:49.800 and they end up with five big factors in this 00:08:49.800 --> 00:08:51.260 most widely used one. 00:08:51.260 --> 00:08:53.520 So here's two of them. 00:08:53.520 --> 00:08:55.440 And here comes a big thing. 00:08:55.440 --> 00:08:58.540 They have the factor which is basically just mathematically 00:08:58.540 --> 00:09:00.950 a set of adjectives that travel together, that are 00:09:00.950 --> 00:09:04.080 highly correlated when people describe themselves. 00:09:04.080 --> 00:09:05.855 And they're somewhat anti-correlated or 00:09:05.855 --> 00:09:07.470 uncorrelated with the other dimensions. 00:09:07.470 --> 00:09:09.950 That's purely empirical. 00:09:09.950 --> 00:09:12.380 Now, though, they have the set of adjectives, like carefree 00:09:12.380 --> 00:09:16.670 or dependable, not hard-working or hard-working. 00:09:16.670 --> 00:09:19.960 Now they have to say, what's the label I'm going to put on 00:09:19.960 --> 00:09:22.500 that dimension of human personality? 00:09:22.500 --> 00:09:23.700 There's no science for that. 00:09:23.700 --> 00:09:24.730 That's judgment. 00:09:24.730 --> 00:09:26.220 But five of them get fixed. 00:09:26.220 --> 00:09:30.220 And once these got fixed, they've become the terminology 00:09:30.220 --> 00:09:31.560 of the field. 00:09:31.560 --> 00:09:33.780 So they said, we're going to call one conscientiousness. 00:09:33.780 --> 00:09:37.170 Those are people who say they're not carefree, they are 00:09:37.170 --> 00:09:38.820 dependable, and they are hard-working. 00:09:38.820 --> 00:09:40.810 Does that make sense? 00:09:40.810 --> 00:09:42.050 Or somebody's agreeable-- 00:09:42.050 --> 00:09:44.440 that's one of the other big five, separate five. 00:09:44.440 --> 00:09:47.970 If somebody says, I'm pretty compliant, I'm pretty kind, 00:09:47.970 --> 00:09:50.070 and I'm seldom rude. 00:09:50.070 --> 00:09:51.840 So I'm going to give you a minute to try this. 00:09:51.840 --> 00:09:53.160 You can fill it out fully. 00:09:53.160 --> 00:09:56.320 So your piece of paper that you have is a 00:09:56.320 --> 00:09:57.910 version of this test. 00:09:57.910 --> 00:09:59.110 It's the real thing. 00:09:59.110 --> 00:10:00.620 One side tells you how to score it. 00:10:00.620 --> 00:10:03.880 Don't look at that, the other side at the bottom. 00:10:03.880 --> 00:10:06.430 Just try a few items for fun if you feel like it. 00:10:06.430 --> 00:10:12.160 And you can fill it out later and score yourself or print it 00:10:12.160 --> 00:10:14.860 out from the notes and score your friends. 00:10:14.860 --> 00:10:16.230 Use it responsibly, the knowledge. 00:10:20.390 --> 00:10:22.610 And you can just have an intuition of what does it 00:10:22.610 --> 00:10:25.370 mean, because almost all personality research, almost 00:10:25.370 --> 00:10:27.830 all of it does exactly what you're doing now, which is 00:10:27.830 --> 00:10:31.160 gives you a piece of paper, and have you describe yourself 00:10:31.160 --> 00:10:32.410 to yourself. 00:10:41.160 --> 00:10:42.930 I'll give you a minute just to get a feeling for it. 00:10:42.930 --> 00:10:45.880 I think it's kind of fun. 00:10:45.880 --> 00:10:47.990 And the feeling you get, like-- 00:10:47.990 --> 00:10:49.860 so people worry about stuff, like who are you comparing 00:10:49.860 --> 00:10:50.560 yourself to? 00:10:50.560 --> 00:10:52.250 If you're outgoing, compared to who? 00:10:52.250 --> 00:10:54.000 Compared to Robin Williams, OK? 00:10:54.000 --> 00:10:55.560 Maybe not so much. 00:10:55.560 --> 00:10:57.290 Compared to your roommate? 00:10:57.290 --> 00:10:58.170 Maybe yes. 00:10:58.170 --> 00:11:00.520 So all these questions, like where do you get these number 00:11:00.520 --> 00:11:03.740 from, how do you come to these answers, and so on. 00:11:03.740 --> 00:11:05.670 People worry about polishing your image. 00:11:05.670 --> 00:11:08.235 Oh yes, I'm always polite. 00:11:08.235 --> 00:11:11.910 I'm nearly perfect when I'm asked to describe myself, OK? 00:11:11.910 --> 00:11:13.510 So to the extent that people did that, it 00:11:13.510 --> 00:11:14.180 wouldn't work, right? 00:11:14.180 --> 00:11:16.200 Because everybody would look perfect all the time. 00:11:22.310 --> 00:11:26.640 So these big five are openness, conscientiousness, 00:11:26.640 --> 00:11:29.880 extroversion, agreeableness, and neuroticism. 00:11:29.880 --> 00:11:33.060 And for memorizing for tests, OCEAN is the acronym. 00:11:35.970 --> 00:11:39.790 These were the ones that have come out as five separable 00:11:39.790 --> 00:11:42.220 dimensions that seem to cover a tremendous amount of 00:11:42.220 --> 00:11:45.620 individual descriptions of human personality, and are 00:11:45.620 --> 00:11:46.870 widely used in research. 00:11:49.450 --> 00:11:51.635 So here's your big five inventory. 00:11:54.670 --> 00:11:56.590 Here's-- 00:11:56.590 --> 00:11:59.460 on the backside, how to score it, if you feel like figuring 00:11:59.460 --> 00:12:02.900 out what this test would say about yourself, OK? 00:12:02.900 --> 00:12:05.740 You could be honest with your scoring, because we're not 00:12:05.740 --> 00:12:07.470 going to collect it, it's just you describing you to 00:12:07.470 --> 00:12:08.720 yourself, if you're curious. 00:12:11.205 --> 00:12:12.370 And now I'm going to go on. 00:12:12.370 --> 00:12:14.030 And you're more than welcome to finish it 00:12:14.030 --> 00:12:14.640 whenever you want. 00:12:14.640 --> 00:12:16.380 It's yours to keep. 00:12:16.380 --> 00:12:19.090 And here's how we would score it, or you would score it. 00:12:19.090 --> 00:12:21.520 It tells you on the bottom what to do. 00:12:21.520 --> 00:12:22.260 For conscientiousness-- 00:12:22.260 --> 00:12:23.310 and we'll come back to this, it's a 00:12:23.310 --> 00:12:25.180 really interesting measure. 00:12:25.180 --> 00:12:26.960 If you rate yourself as somebody who does a thorough 00:12:26.960 --> 00:12:29.880 job, is a reliable worker, perseveres until the task is 00:12:29.880 --> 00:12:32.620 finished, does things efficiently, and makes plans 00:12:32.620 --> 00:12:34.790 and follows through with them. 00:12:34.790 --> 00:12:36.650 The higher you rate yourself on those-- this makes sense-- 00:12:36.650 --> 00:12:39.300 you're more conscientious, right? 00:12:39.300 --> 00:12:43.870 The less you say, that you're somewhat careless, you tend to 00:12:43.870 --> 00:12:47.290 be disorganized, you tend to be lazy, and you're easily 00:12:47.290 --> 00:12:49.090 distracted, well, those are negative 00:12:49.090 --> 00:12:50.530 things for that dimension. 00:12:50.530 --> 00:12:51.540 Does that make sense? 00:12:51.540 --> 00:12:53.060 So you have to watch when you score it which are the 00:12:53.060 --> 00:12:54.980 positive and which are the negative as you score them, 00:12:54.980 --> 00:12:56.980 would you get a plus or a minus. 00:12:56.980 --> 00:12:59.020 And they try to make it either way, so that if you constantly 00:12:59.020 --> 00:13:03.120 say yes, you ought not to score anything that makes 00:13:03.120 --> 00:13:04.810 sense, even to yourself. 00:13:04.810 --> 00:13:08.760 Anyway, so here's the big questions, right? 00:13:08.760 --> 00:13:10.380 All this sort of research behind or this factor 00:13:10.380 --> 00:13:12.050 analysis, you'd want to know two things. 00:13:12.050 --> 00:13:12.680 Are they stable? 00:13:12.680 --> 00:13:15.090 Do they really describe a person across 00:13:15.090 --> 00:13:16.750 situations and time? 00:13:16.750 --> 00:13:18.420 That's what we mean by personality. 00:13:18.420 --> 00:13:21.010 And secondly, do they predict behaviors and life outcomes? 00:13:21.010 --> 00:13:23.110 Is there something about them that goes with things that we 00:13:23.110 --> 00:13:26.450 care about, variably across people? 00:13:26.450 --> 00:13:31.050 So where people have looked at this over some number of 00:13:31.050 --> 00:13:34.470 years, it correlates 0.5 to 0.7 across 30 00:13:34.470 --> 00:13:36.980 or 40 years of life. 00:13:36.980 --> 00:13:40.360 Height and sex, to think about it, correlates 0.4. 00:13:40.360 --> 00:13:42.880 Again, height and sex is kind of an-- people will pick that 00:13:42.880 --> 00:13:43.480 to think about. 00:13:43.480 --> 00:13:46.100 On average, men tend to be taller than women, but lots of 00:13:46.100 --> 00:13:49.330 women are taller than lots of individual men, OK? 00:13:49.330 --> 00:13:52.530 So it's a stronger relationship across time. 00:13:52.530 --> 00:13:54.520 It's more stable than what you'd predict 00:13:54.520 --> 00:13:56.180 by height and sex. 00:13:56.180 --> 00:13:57.830 And here's something really interesting. 00:13:57.830 --> 00:13:59.890 They tested people across seven years-- within 00:13:59.890 --> 00:14:03.970 childhood, within young adulthood, within the 30s, and 00:14:03.970 --> 00:14:05.220 in the 50 to 70 age range. 00:14:05.220 --> 00:14:06.770 And here's something kind of striking. 00:14:06.770 --> 00:14:09.930 If you test people twice across seven years, starting 00:14:09.930 --> 00:14:14.730 from infancy as best you can-- or questions about them 00:14:14.730 --> 00:14:16.980 because they can't fill out forms-- 00:14:16.980 --> 00:14:19.970 to adulthood, the striking thing is that the older you 00:14:19.970 --> 00:14:22.780 get, the more consistent you become across 00:14:22.780 --> 00:14:24.240 a seven year period. 00:14:24.240 --> 00:14:27.430 The older you get, the more consistent you become. 00:14:27.430 --> 00:14:28.910 So how might you interpret that? 00:14:33.070 --> 00:14:34.140 There's a couple different ways you 00:14:34.140 --> 00:14:35.750 could think about that. 00:14:35.750 --> 00:14:39.990 The older you become, the more consistent you become in 00:14:39.990 --> 00:14:41.160 describing your personality-- 00:14:41.160 --> 00:14:42.550 let's pretend your descriptions are accurate-- 00:14:42.550 --> 00:14:45.940 the more consistent your personality is. 00:14:45.940 --> 00:14:47.050 Did you expect that? 00:14:47.050 --> 00:14:47.820 Is that what you expect? 00:14:47.820 --> 00:14:50.117 Something opposite? 00:14:50.117 --> 00:14:51.115 Yeah? 00:14:51.115 --> 00:14:53.776 AUDIENCE: They get older, they kind of develop habits and get 00:14:53.776 --> 00:14:55.110 set in their ways. 00:14:55.110 --> 00:14:55.540 PROFESSOR: Yeah. 00:14:55.540 --> 00:14:58.620 So there's two ways to describe getting older. 00:14:58.620 --> 00:15:00.880 Like me, I get set in my ways. 00:15:00.880 --> 00:15:01.840 Right? 00:15:01.840 --> 00:15:03.420 That's OK. 00:15:03.420 --> 00:15:06.770 Or I'll say it the other way, we discover the ways that we 00:15:06.770 --> 00:15:07.700 really like. 00:15:07.700 --> 00:15:09.660 OK? 00:15:09.660 --> 00:15:12.620 My friend Robert Sapolsky at Stanford, who writes fantastic 00:15:12.620 --> 00:15:15.410 books and who's a fantastic lecturer, had an essay where 00:15:15.410 --> 00:15:19.960 he said he noticed in his late 40s or 50s, that the people in 00:15:19.960 --> 00:15:24.100 his working lab that they were playing irritating music. 00:15:24.100 --> 00:15:25.970 It was just bothering him when they were playing the music. 00:15:25.970 --> 00:15:30.390 And it was music that people of your generation listen to. 00:15:30.390 --> 00:15:31.450 He said, why is it irritating? 00:15:31.450 --> 00:15:33.860 Because when he played his-- 00:15:33.860 --> 00:15:35.590 when he played The Beatles or whatever, they were irritating 00:15:35.590 --> 00:15:37.050 to his parents, OK. 00:15:37.050 --> 00:15:38.440 So what's going on? 00:15:38.440 --> 00:15:39.430 And he said, oh. 00:15:39.430 --> 00:15:42.440 And so he did a little informal study, he talked to 00:15:42.440 --> 00:15:45.230 people of different ages and people in restaurants, they 00:15:45.230 --> 00:15:49.020 said, at what age do people seem to stop wanting to do new 00:15:49.020 --> 00:15:52.180 things, and get stuck in their ways, or find what they like 00:15:52.180 --> 00:15:53.170 and stick with it? 00:15:53.170 --> 00:15:54.810 And there's no one answer. 00:15:54.810 --> 00:15:57.180 But he found a tremendous number of people, by about 30 00:15:57.180 --> 00:16:01.010 to 35, that's their music, they like sushi or they don't 00:16:01.010 --> 00:16:03.100 like sushi. 00:16:03.100 --> 00:16:05.910 They have their set of stuff that they have going for them 00:16:05.910 --> 00:16:06.920 or they don't like. 00:16:06.920 --> 00:16:09.500 And so you could say they get stuck in their ways. 00:16:09.500 --> 00:16:11.730 You could say they discover what they like 00:16:11.730 --> 00:16:12.920 and stick with it. 00:16:12.920 --> 00:16:16.260 And here's an age more of exploration and variability. 00:16:16.260 --> 00:16:18.150 Who knows? 00:16:18.150 --> 00:16:20.200 But it's kind of interesting, the older you get, the more 00:16:20.200 --> 00:16:21.962 consistent you get. 00:16:21.962 --> 00:16:23.550 Is this flexibility? 00:16:23.550 --> 00:16:25.080 Is this chaos? 00:16:25.080 --> 00:16:26.220 You could look at it either way. 00:16:26.220 --> 00:16:29.020 There's no real answer. 00:16:29.020 --> 00:16:31.010 People have looked at these scores and asked whether 00:16:31.010 --> 00:16:31.815 things like-- 00:16:31.815 --> 00:16:35.010 do they vary with age and gender? 00:16:35.010 --> 00:16:41.270 So for example, these broken lines are neuroticism, which 00:16:41.270 --> 00:16:42.010 is a funny label. 00:16:42.010 --> 00:16:42.970 It really means-- 00:16:42.970 --> 00:16:45.830 neuroticism is the bad side of it, stability is the 00:16:45.830 --> 00:16:46.490 good side of it. 00:16:46.490 --> 00:16:50.650 You could also say too stable could be boring and inert. 00:16:50.650 --> 00:16:53.930 You could relabel these things pretty much. 00:16:53.930 --> 00:16:58.330 But on average, women's scores are a little bit less stable 00:16:58.330 --> 00:17:01.280 than men, a little bit more outgoing, a little bit. 00:17:01.280 --> 00:17:03.210 By age, you get a few trends. 00:17:03.210 --> 00:17:05.760 This will not surprise you, actually. 00:17:05.760 --> 00:17:12.210 So for neuroticism-- again, stability-- 00:17:12.210 --> 00:17:14.540 that neuroticism decreases with age. 00:17:14.540 --> 00:17:16.640 People get more stable and they get more conscientious as 00:17:16.640 --> 00:17:17.140 they get older. 00:17:17.140 --> 00:17:18.460 You kind of expect that. 00:17:18.460 --> 00:17:21.770 People get more used to their habits and more stuck in their 00:17:21.770 --> 00:17:25.829 ways, that we would call stability. 00:17:25.829 --> 00:17:29.090 So, let's ask for people who score high or low on these 00:17:29.090 --> 00:17:31.330 measures, what do they go with? 00:17:31.330 --> 00:17:33.970 So for these five fundamental personality measures. 00:17:33.970 --> 00:17:37.010 So people who score highly on the neuroticism scale-- again, 00:17:37.010 --> 00:17:38.410 these labels are tricky-- 00:17:38.410 --> 00:17:42.100 but it means ranging from very stable and emotional sense to 00:17:42.100 --> 00:17:43.680 very labile-- 00:17:43.680 --> 00:17:45.790 they pay more attention to threat in the environment, 00:17:45.790 --> 00:17:48.280 more stressed when given a surprise math test, have a 00:17:48.280 --> 00:17:50.320 higher divorce rate, more susceptible to 00:17:50.320 --> 00:17:52.690 depression and anxiety. 00:17:52.690 --> 00:17:56.000 At the very, very, very highest scores of neuroticism, 00:17:56.000 --> 00:17:59.290 it's a big risk for depression and anxiety. 00:17:59.290 --> 00:18:01.900 And one of the deep questions always is, to what extent are 00:18:01.900 --> 00:18:06.250 what we call psychiatric labels extremes of personality 00:18:06.250 --> 00:18:08.060 or something beyond personality? 00:18:08.060 --> 00:18:09.890 This is a much deeper issue than you'd think. 00:18:09.890 --> 00:18:11.840 We'll come back to it in psychiatry. 00:18:11.840 --> 00:18:14.840 Because some people say there's no such thing, for 00:18:14.840 --> 00:18:17.100 example, as social anxiety disorder. 00:18:17.100 --> 00:18:18.590 It's a recent invention for what people 00:18:18.590 --> 00:18:21.540 used to call shyness. 00:18:21.540 --> 00:18:23.540 I don't think that's right, mostly. 00:18:23.540 --> 00:18:27.270 But this debate goes on, because there's not a sharp 00:18:27.270 --> 00:18:32.410 boundary between being a little shy and so shy that you 00:18:32.410 --> 00:18:33.980 don't leave your house to meet people. 00:18:33.980 --> 00:18:34.950 That's kind of an extreme. 00:18:34.950 --> 00:18:36.330 But most people-- 00:18:36.330 --> 00:18:38.890 it's not one person is here and the next person's here, 00:18:38.890 --> 00:18:40.380 there's people all along the continuum. 00:18:40.380 --> 00:18:44.090 Where you draw the line is a challenging issue. 00:18:44.090 --> 00:18:46.370 Highly extroverted people versus highly introverted, 00:18:46.370 --> 00:18:48.410 that sort of shyness and outgoingness. 00:18:48.410 --> 00:18:49.400 This will be a big surprise. 00:18:49.400 --> 00:18:51.930 Highly extroverted people-- by these personality measures-- 00:18:51.930 --> 00:18:54.200 attend more parties, they're more popular, they're 00:18:54.200 --> 00:18:56.140 identified as leaders in college, they live with and 00:18:56.140 --> 00:18:59.380 work with more people, they're less disturbed by sudden loud 00:18:59.380 --> 00:19:00.400 sounds or intense stimuli. 00:19:00.400 --> 00:19:02.690 You can do experiments in a laboratory and get these 00:19:02.690 --> 00:19:03.960 differences. 00:19:03.960 --> 00:19:05.080 None of these are sort of surprising. 00:19:05.080 --> 00:19:06.260 They're just telling you there's something correct 00:19:06.260 --> 00:19:08.110 about these personality measures. 00:19:08.110 --> 00:19:11.410 Highly agreeable people are more willing to lend money, 00:19:11.410 --> 00:19:12.750 have higher high school grades, and have 00:19:12.750 --> 00:19:14.860 fewer arrests as adults. 00:19:14.860 --> 00:19:16.760 But the cool thing is not-- 00:19:16.760 --> 00:19:17.560 I mean, you're not surprised. 00:19:17.560 --> 00:19:19.690 But the fact that they fill out a questionnaire sitting at 00:19:19.690 --> 00:19:22.870 a desk like you do, predicts to some decent extent over the 00:19:22.870 --> 00:19:24.830 population whether they'll go to jail or not. 00:19:24.830 --> 00:19:27.330 That's kind of interesting. 00:19:27.330 --> 00:19:28.700 More openness to experience. 00:19:28.700 --> 00:19:30.140 You're more likely to major in the humanities-- 00:19:33.130 --> 00:19:34.380 not us-- 00:19:38.330 --> 00:19:42.040 change careers in midlife, perform better in job training 00:19:42.040 --> 00:19:44.810 programs, and play a musical instrument. 00:19:44.810 --> 00:19:46.970 But these are massive statistical things. 00:19:46.970 --> 00:19:49.630 Because kind of conversely-- 00:19:49.630 --> 00:19:53.290 well, you know there's very interesting relations between 00:19:53.290 --> 00:19:55.500 musicality and sort of math and science backgrounds. 00:19:55.500 --> 00:19:56.900 So that seems to go against this. 00:19:56.900 --> 00:19:59.370 So these are big averages. 00:19:59.370 --> 00:20:02.860 Maybe, I think, in some ways the most interesting one, for 00:20:02.860 --> 00:20:05.930 practical reasons, has turned out to be conscientiousness, 00:20:05.930 --> 00:20:08.370 and that's like doing what you're supposed to do. 00:20:08.370 --> 00:20:10.830 More sexually faithful to spouses, higher job ratings, 00:20:10.830 --> 00:20:13.980 smoke less, drink less, drive more safely, live longer, less 00:20:13.980 --> 00:20:16.690 risk for Alzheimer's Disease-- spectacularly less risk. 00:20:16.690 --> 00:20:17.800 OK? 00:20:17.800 --> 00:20:19.660 And also play a musical instrument? 00:20:23.280 --> 00:20:28.620 So the Alzheimer's Disease is kind of interesting, because 00:20:28.620 --> 00:20:30.880 what we think is happening-- and we don't really know-- 00:20:30.880 --> 00:20:31.220 is this. 00:20:31.220 --> 00:20:33.770 So you may know there's basically one gene, now, more 00:20:33.770 --> 00:20:35.950 recently, a couple other genes, identified as 00:20:35.950 --> 00:20:38.020 significant risk genes for Alzheimer's. 00:20:38.020 --> 00:20:40.080 But the one powerful well-identified one is the 00:20:40.080 --> 00:20:42.190 so-called APOE gene. 00:20:42.190 --> 00:20:43.740 And that is a significant risk gene. 00:20:43.740 --> 00:20:48.920 If you're homologous for that, you have a higher risk for 00:20:48.920 --> 00:20:50.060 Alzheimer's. 00:20:50.060 --> 00:20:52.910 But that best-known, best-characterized gene is a 00:20:52.910 --> 00:20:59.100 far smaller risk factor, mathematically, than being low 00:20:59.100 --> 00:21:01.180 conscientiousness. 00:21:01.180 --> 00:21:03.920 And we don't know what that really means, right? 00:21:03.920 --> 00:21:05.460 What's your guess? 00:21:05.460 --> 00:21:06.730 And nobody knows. 00:21:06.730 --> 00:21:08.280 This is just an empirical finding, and it's been 00:21:08.280 --> 00:21:09.400 replicated a number of times. 00:21:09.400 --> 00:21:11.900 What's your guess? 00:21:11.900 --> 00:21:14.040 So conscientious people do what they're supposed to. 00:21:14.040 --> 00:21:15.850 All the things that you're supposed to, in the morning, 00:21:15.850 --> 00:21:18.190 get up and do, they do them pretty well. 00:21:18.190 --> 00:21:19.440 Right? 00:21:21.090 --> 00:21:24.690 Make your bed, do your laundry regularly, brush your teeth 00:21:24.690 --> 00:21:28.210 regularly, have your medical appointments regularly, eat 00:21:28.210 --> 00:21:30.830 well, exercise, all the things that everybody tells you is 00:21:30.830 --> 00:21:32.560 good for you, conscientious people are more 00:21:32.560 --> 00:21:33.070 likely to do it. 00:21:33.070 --> 00:21:33.890 Yeah? 00:21:33.890 --> 00:21:35.360 AUDIENCE: It's sort of an analogy. 00:21:35.360 --> 00:21:38.300 The thing is that someone who continuously uses them more-- 00:21:38.300 --> 00:21:40.260 more of the pipeline, basically. 00:21:40.260 --> 00:21:43.036 Keep water going through them, makes it less likely that it 00:21:43.036 --> 00:21:45.160 will clog the pipes-- 00:21:45.160 --> 00:21:46.910 PROFESSOR: Yeah, it's something like that. 00:21:46.910 --> 00:21:48.060 The pipeline analogy. 00:21:48.060 --> 00:21:50.440 If you keep flushing it regularly, instead of clogging 00:21:50.440 --> 00:21:53.130 it up with bad things that are bad for you or whatever. 00:21:53.130 --> 00:21:55.180 In the end, there has to be a biological mechanism. 00:21:55.180 --> 00:21:56.020 In the end, there has to be. 00:21:56.020 --> 00:21:58.380 But maybe it's a lifetime of doing healthy things. 00:21:58.380 --> 00:22:00.940 And they add up and up, day in, day out, month in, month 00:22:00.940 --> 00:22:02.410 out, year in, year out. 00:22:02.410 --> 00:22:05.190 That they somehow, in some way, either fend off 00:22:05.190 --> 00:22:07.980 Alzheimer's disease or diminish its expression for 00:22:07.980 --> 00:22:08.570 much longer. 00:22:08.570 --> 00:22:09.690 Does that sound OK? 00:22:09.690 --> 00:22:13.170 But it's a very compelling finding. 00:22:13.170 --> 00:22:13.400 All right. 00:22:13.400 --> 00:22:15.040 So then there's always a fun question up for our 00:22:15.040 --> 00:22:16.460 personality, and there will be one big 00:22:16.460 --> 00:22:18.570 surprise here, I think. 00:22:18.570 --> 00:22:20.325 I'll tell you this is our surprise. 00:22:20.325 --> 00:22:22.430 [INAUDIBLE] was reminding me that-- 00:22:22.430 --> 00:22:23.940 there's a parents visiting weekend, which 00:22:23.940 --> 00:22:25.260 is not today, right? 00:22:25.260 --> 00:22:28.160 But a few years ago, I gave this lecture on that, and I 00:22:28.160 --> 00:22:31.870 came to a conclusion that parents will find impossible, 00:22:31.870 --> 00:22:34.390 untrue, and very disturbing. 00:22:34.390 --> 00:22:36.030 Get ready. 00:22:36.030 --> 00:22:38.280 Here we go. 00:22:38.280 --> 00:22:40.560 Again, we're always curious, our personalities-- 00:22:40.560 --> 00:22:42.310 whether we're outgoing or not, agreeable or 00:22:42.310 --> 00:22:43.500 not, open or not-- 00:22:43.500 --> 00:22:45.560 how much of that is in our genes at birth, how much is 00:22:45.560 --> 00:22:48.610 that in our environment in terms of parental influence, 00:22:48.610 --> 00:22:51.440 and sibling influence, and school, and so on. 00:22:51.440 --> 00:22:54.800 So the usual way to this, until we know the true biology 00:22:54.800 --> 00:22:58.110 of this, are estimates from twin studies and children 00:22:58.110 --> 00:22:59.430 reared apart and reared separately. 00:22:59.430 --> 00:23:01.330 So let me start with the twin studies. 00:23:01.330 --> 00:23:06.270 So these are identical twins in green versus dizygotic or 00:23:06.270 --> 00:23:08.260 fraternal twins, shared 00:23:08.260 --> 00:23:09.910 environment, some shared genes. 00:23:09.910 --> 00:23:13.230 The difference about this is thought to be an estimate of 00:23:13.230 --> 00:23:15.040 pure genetic heritability. 00:23:15.040 --> 00:23:17.030 And say you get a pretty good one-- 00:23:17.030 --> 00:23:19.510 extroversion and openness the most, maybe-- 00:23:19.510 --> 00:23:26.000 but definitely a genetic contribution to personality. 00:23:26.000 --> 00:23:29.390 That's the evidence from twin studies. 00:23:29.390 --> 00:23:32.180 And it's even impressive if you do not self report 00:23:32.180 --> 00:23:34.160 questionnaires, but behaviors that people describe, 00:23:34.160 --> 00:23:35.340 activities they do. 00:23:35.340 --> 00:23:37.060 Time spent watching television, number of 00:23:37.060 --> 00:23:39.870 childhood accidents, tendency for marriage and divorce, 00:23:39.870 --> 00:23:43.230 religious attitudes, your balance between work and 00:23:43.230 --> 00:23:46.340 leisure, do you want to be at work all the time or leisure, 00:23:46.340 --> 00:23:47.710 or what the balance ought to be. 00:23:47.710 --> 00:23:51.820 0.5, that's about half heritable, estimated. 00:23:51.820 --> 00:23:52.440 Happiness-- 00:23:52.440 --> 00:23:53.760 we'll come back to happiness ratings. 00:23:53.760 --> 00:23:57.040 The way people rate happiness, it turns out, is if you do a 00:23:57.040 --> 00:23:58.760 one to seven scale, that's the field. 00:23:58.760 --> 00:23:59.330 OK? 00:23:59.330 --> 00:24:01.310 Seven means happy all the time, one means 00:24:01.310 --> 00:24:03.230 miserable all the time. 00:24:03.230 --> 00:24:04.710 That's the way happiness research is done. 00:24:04.710 --> 00:24:07.140 In the last lecture, we'll talk about what people think 00:24:07.140 --> 00:24:10.040 people need to do to be happy. 00:24:10.040 --> 00:24:13.150 But one thing we know is that people tend to have happiness 00:24:13.150 --> 00:24:13.950 set-points-- 00:24:13.950 --> 00:24:16.340 you may know this amongst your friends or yourselves-- 00:24:16.340 --> 00:24:19.430 that is, on average, a person will be very happy, or 00:24:19.430 --> 00:24:23.110 moderately happy, or pretty grumbly most of the time. 00:24:23.110 --> 00:24:23.680 OK? 00:24:23.680 --> 00:24:25.530 Something happens in their lives that's really good or 00:24:25.530 --> 00:24:27.390 bad, they'll move a little bit, but they'll slide right 00:24:27.390 --> 00:24:28.030 back to it. 00:24:28.030 --> 00:24:31.070 There's nothing better or worse about one or the other, 00:24:31.070 --> 00:24:32.570 but it's just people tend to be pretty set. 00:24:32.570 --> 00:24:35.590 And the estimates from twin studies are about half of your 00:24:35.590 --> 00:24:39.110 chronic sense of happiness, day in and day out, it comes 00:24:39.110 --> 00:24:41.840 from genes, is the estimate. 00:24:41.840 --> 00:24:44.320 So that's a big piece. 00:24:44.320 --> 00:24:45.760 But here's the kind of stunning thing. 00:24:45.760 --> 00:24:47.530 And in the next couple slides I tell you. 00:24:47.530 --> 00:24:48.644 Let me tell you the bottom line, let me 00:24:48.644 --> 00:24:51.040 tell you the evidence. 00:24:51.040 --> 00:24:54.440 The empirical evidence could support a position that 00:24:54.440 --> 00:24:58.450 parents and family environments have zero 00:24:58.450 --> 00:25:01.490 influence on your personality. 00:25:01.490 --> 00:25:04.400 Then the question is, what is the environmental influence? 00:25:04.400 --> 00:25:06.270 Because we know it's not all genetic. 00:25:06.270 --> 00:25:10.320 But wherever it's been looked at carefully, parents and home 00:25:10.320 --> 00:25:15.270 environments appear to have, as far as they can see, nearly 00:25:15.270 --> 00:25:16.820 zero influence on your personality. 00:25:16.820 --> 00:25:19.670 Now this is the thing that drives parents crazy. 00:25:19.670 --> 00:25:21.780 Because as a parent, I can tell you, from the moment 00:25:21.780 --> 00:25:24.010 they're born, or even months before children are born, to 00:25:24.010 --> 00:25:26.560 the moment you're no longer around to take care of your 00:25:26.560 --> 00:25:29.410 children, you want them to develop the right kind of-- 00:25:29.410 --> 00:25:31.620 be a happy person, a good person. 00:25:31.620 --> 00:25:34.230 Hopefully something about conscientiousness, do well in 00:25:34.230 --> 00:25:35.340 life, right? 00:25:35.340 --> 00:25:37.480 And you're doing every little thing to encourage that. 00:25:37.480 --> 00:25:40.170 The comments you make, the schools you send them to, the 00:25:40.170 --> 00:25:42.940 activities you encourage them to do, you want them to have a 00:25:42.940 --> 00:25:45.750 personality that will be happy for them and good for them and 00:25:45.750 --> 00:25:47.190 thriving, right? 00:25:47.190 --> 00:25:51.180 So to be told that whatever you do doesn't matter is kind 00:25:51.180 --> 00:25:52.200 of a big shock. 00:25:52.200 --> 00:25:53.990 And we don't really know the depth of this. 00:25:53.990 --> 00:25:55.420 And it sounds like it's ridiculous. 00:25:55.420 --> 00:25:57.090 But I can tell you the empirical evidence kind of 00:25:57.090 --> 00:25:58.390 supports it. 00:25:58.390 --> 00:26:02.350 So for example, for the twin studies, it makes no 00:26:02.350 --> 00:26:04.940 difference at all for personality dimensions whether 00:26:04.940 --> 00:26:09.030 twins are raised together or raised apart. 00:26:09.030 --> 00:26:11.650 So they're in different families or the same family-- 00:26:11.650 --> 00:26:12.550 doesn't make a difference. 00:26:12.550 --> 00:26:14.600 All the heritable estimates remain exactly the same. 00:26:14.600 --> 00:26:18.080 So where are the environmental factors coming from? 00:26:18.080 --> 00:26:19.840 We believe there's environmental factors, but we 00:26:19.840 --> 00:26:21.760 can't spot them. 00:26:21.760 --> 00:26:24.805 And what's fascinating about these things is that we as 00:26:24.805 --> 00:26:27.010 human beings-- and this is just an example now-- 00:26:27.010 --> 00:26:31.060 always want to understand who we are as some sort of willful 00:26:31.060 --> 00:26:34.150 response to our environment. 00:26:34.150 --> 00:26:38.450 So here are two identical twins reared apart. 00:26:38.450 --> 00:26:40.760 And they're both super neat. 00:26:40.760 --> 00:26:42.270 OK? 00:26:42.270 --> 00:26:46.210 And neither one of them tells you, well, it's in my genes, 00:26:46.210 --> 00:26:47.320 what else was I going to do? 00:26:47.320 --> 00:26:49.520 None of us mostly think that. 00:26:49.520 --> 00:26:52.600 Outside of some dire circumstances or diseases, we 00:26:52.600 --> 00:26:55.860 mostly think, it's my choice this morning whether I'm going 00:26:55.860 --> 00:26:56.830 to make my bed or not. 00:26:56.830 --> 00:27:00.020 It's my choice if I do laundry this year or not. 00:27:00.020 --> 00:27:01.206 Yeah. 00:27:01.206 --> 00:27:05.400 AUDIENCE: Could that other 50% come from things part of the 00:27:05.400 --> 00:27:07.060 environment like diet or health? 00:27:07.060 --> 00:27:09.290 PROFESSOR: Could the other 50% come from things like diet or 00:27:09.290 --> 00:27:10.280 other things in the environment? 00:27:10.280 --> 00:27:13.400 It could. 00:27:13.400 --> 00:27:16.850 But even that tends to go by families some. 00:27:16.850 --> 00:27:19.720 Some families just say, here's a few years worth of potato 00:27:19.720 --> 00:27:21.230 chips, good luck. 00:27:21.230 --> 00:27:23.370 Another family's going, oh my gosh, you didn't eat carrots 00:27:23.370 --> 00:27:25.500 all month long. 00:27:25.500 --> 00:27:27.960 Even that tends to be, on average, someone 00:27:27.960 --> 00:27:28.880 environmental, right? 00:27:28.880 --> 00:27:31.310 Both by economic opportunity, part of the world you're in, 00:27:31.310 --> 00:27:32.950 parental attitudes, right? 00:27:32.950 --> 00:27:33.550 I agree with you. 00:27:33.550 --> 00:27:34.450 It's got to be something. 00:27:34.450 --> 00:27:37.620 And maybe we just don't have the whole story right. 00:27:37.620 --> 00:27:40.210 But here's two twins telling you why each of 00:27:40.210 --> 00:27:41.720 them is very neat. 00:27:41.720 --> 00:27:43.230 OK? 00:27:43.230 --> 00:27:44.250 The first one is, my mother. 00:27:44.250 --> 00:27:47.720 When I was growing up-- this is one household, one twin-- 00:27:47.720 --> 00:27:49.890 she always kept the house perfectly ordered. 00:27:49.890 --> 00:27:50.950 I learned from her. 00:27:50.950 --> 00:27:52.730 What else could I do? 00:27:52.730 --> 00:27:54.730 I had a model in my parent. 00:27:54.730 --> 00:27:56.000 She was neat, I'm neat. 00:27:56.000 --> 00:27:58.180 Here's the other twin, who is also very neat. 00:27:58.180 --> 00:27:59.080 The reason is quite simple. 00:27:59.080 --> 00:28:01.420 I'm reacting to my mother, who was a complete slob. 00:28:01.420 --> 00:28:01.990 OK? 00:28:01.990 --> 00:28:03.850 So they're complete opposite stories. 00:28:03.850 --> 00:28:05.370 I'm modeling my parents. 00:28:05.370 --> 00:28:07.960 I'm rebelling against my parents. 00:28:07.960 --> 00:28:10.510 But you know that they're identical twins, and they end 00:28:10.510 --> 00:28:11.550 up in the same place. 00:28:11.550 --> 00:28:12.433 Yeah? 00:28:12.433 --> 00:28:13.683 AUDIENCE: [INAUDIBLE] 00:28:25.000 --> 00:28:25.920 PROFESSOR: That's another interpretation. 00:28:25.920 --> 00:28:27.000 This is a good question. 00:28:27.000 --> 00:28:29.120 The question is, I'm pretending the explanations 00:28:29.120 --> 00:28:30.630 have nothing to do with anything, and you're saying 00:28:30.630 --> 00:28:31.700 maybe this a personality thing. 00:28:31.700 --> 00:28:34.990 Somebody who chooses to model their parent or just somebody 00:28:34.990 --> 00:28:36.400 who chooses to rebel against their parent. 00:28:36.400 --> 00:28:38.520 Maybe that's the personally dimension, right? 00:28:38.520 --> 00:28:39.770 It could be. 00:28:41.670 --> 00:28:43.810 It's just neatness. 00:28:43.810 --> 00:28:46.010 Twins who aren't neat tend to go the same way and twins who 00:28:46.010 --> 00:28:47.060 are neat tend to go the same way. 00:28:47.060 --> 00:28:49.640 About 50 percent of the effect is in the genes. 00:28:49.640 --> 00:28:50.350 I don't know. 00:28:50.350 --> 00:28:51.650 I'm not saying that things aren't there. 00:28:51.650 --> 00:28:55.430 It's a bit of a mystery, it's a bit of a shock. 00:28:55.430 --> 00:28:57.080 So here's a couple more things. 00:28:57.080 --> 00:28:59.050 Biological, non-twin siblings-- 00:28:59.050 --> 00:29:02.310 OK, so these are siblings but they're not twins-- 00:29:02.310 --> 00:29:04.310 are far more similar to one another 00:29:04.310 --> 00:29:05.940 then adoptive siblings. 00:29:05.940 --> 00:29:06.500 OK. 00:29:06.500 --> 00:29:06.930 That's OK. 00:29:06.930 --> 00:29:09.140 That's the genetics, right? 00:29:09.140 --> 00:29:10.860 Because the adopted child is into the family. 00:29:10.860 --> 00:29:12.390 But here's a shocking one. 00:29:12.390 --> 00:29:15.110 For personality, children are no more similar to an adoptive 00:29:15.110 --> 00:29:18.710 sibling than are two randomly selected children. 00:29:18.710 --> 00:29:22.120 So in a household, if you have an adopted child and a 00:29:22.120 --> 00:29:24.410 biological child in that household, sharing the same 00:29:24.410 --> 00:29:27.830 environment, they are no more similar, one to the other, 00:29:27.830 --> 00:29:31.350 than two random children in the world. 00:29:31.350 --> 00:29:34.820 OK, where is the effect of the environment? 00:29:34.820 --> 00:29:37.550 Where is the parental effect on the two children in terms 00:29:37.550 --> 00:29:39.240 of personality? 00:29:39.240 --> 00:29:42.210 So people have mounted this argument. 00:29:42.210 --> 00:29:43.800 So let me pick another one. 00:29:43.800 --> 00:29:45.070 Put up your hand if you want to. 00:29:45.070 --> 00:29:46.060 I'll put up my hand. 00:29:46.060 --> 00:29:49.540 How many people grew up in a household where one or more 00:29:49.540 --> 00:29:52.310 parents spoke in a noticeable accent? 00:29:52.310 --> 00:29:53.340 I mean, I did. 00:29:53.340 --> 00:29:55.350 Let's just try this here. 00:29:55.350 --> 00:29:58.440 How many of you who have your hand up-- keep your hand up-- 00:29:58.440 --> 00:30:02.380 did you keep your parents' accent? 00:30:02.380 --> 00:30:05.460 Where's the environment? 00:30:05.460 --> 00:30:08.970 In your critical moments of language development, you were 00:30:08.970 --> 00:30:10.730 hearing that accent. 00:30:10.730 --> 00:30:12.420 Where is the environment? 00:30:12.420 --> 00:30:13.850 And you could say, well, yeah, but there are other people 00:30:13.850 --> 00:30:14.550 speaking other things. 00:30:14.550 --> 00:30:18.260 Yeah, but then zero parental influence on the way in which 00:30:18.260 --> 00:30:19.520 you produce your language. 00:30:19.520 --> 00:30:21.840 So there's a lot of different things to think as we move 00:30:21.840 --> 00:30:24.700 from language to personality, but it's turning out to be 00:30:24.700 --> 00:30:26.810 surprisingly hard on some dimensions to show an 00:30:26.810 --> 00:30:30.610 influence of parental environment on child 00:30:30.610 --> 00:30:31.730 development, especially in personality. 00:30:31.730 --> 00:30:32.548 Yeah. 00:30:32.548 --> 00:30:35.964 AUDIENCE: So, first off, for the adopted sibling thing. 00:30:35.964 --> 00:30:39.380 It seems like that way, not only would they get similar 00:30:39.380 --> 00:30:42.308 parental environment, but they also probably have similar 00:30:42.308 --> 00:30:43.290 school environment-- 00:30:43.290 --> 00:30:43.690 PROFESSOR: Oh, yes. 00:30:43.690 --> 00:30:45.710 It's worse than that. 00:30:45.710 --> 00:30:46.810 This is a very good question. 00:30:46.810 --> 00:30:49.120 It's not only that they have adoptive parents, if they have 00:30:49.120 --> 00:30:50.780 another kid in the house, there's another kid in the 00:30:50.780 --> 00:30:53.590 house, they probably go to the same-- if they go to church or 00:30:53.590 --> 00:30:57.150 synagogue or anything like that. 00:30:57.150 --> 00:31:02.680 Same school, same state, same influence of whoever's the NBA 00:31:02.680 --> 00:31:04.870 basketball champion. 00:31:04.870 --> 00:31:05.770 The whole list. 00:31:05.770 --> 00:31:07.290 And it seems to be-- 00:31:07.290 --> 00:31:09.206 you can't identify anything in that. 00:31:09.206 --> 00:31:10.870 Yeah? 00:31:10.870 --> 00:31:16.226 AUDIENCE: Something that is biological but not in DNA, 00:31:16.226 --> 00:31:17.710 that is also 50-50? 00:31:17.710 --> 00:31:18.260 PROFESSOR: Yeah. 00:31:18.260 --> 00:31:20.330 So diet would influence that. 00:31:20.330 --> 00:31:22.782 Who knows? 00:31:22.782 --> 00:31:24.856 AUDIENCE: Stuff like you're born with, so that it's not 00:31:24.856 --> 00:31:27.662 just as an environmental thing, but it's not, strictly 00:31:27.662 --> 00:31:29.630 speaking, in your DNA. 00:31:29.630 --> 00:31:32.150 Because that's what identical twins-- 00:31:32.150 --> 00:31:34.630 PROFESSOR: Well, let me stop you there for one moment. 00:31:34.630 --> 00:31:37.770 I think at some level of analysis, all environmental 00:31:37.770 --> 00:31:38.290 influences-- 00:31:38.290 --> 00:31:40.580 education, parenting, everything-- 00:31:40.580 --> 00:31:44.410 will have a biological counterpart in your body and 00:31:44.410 --> 00:31:46.360 in your brain, right? 00:31:46.360 --> 00:31:49.280 Because the environment has to affect you by how it changes 00:31:49.280 --> 00:31:51.630 your body or brain. 00:31:51.630 --> 00:31:52.540 After you're born. 00:31:52.540 --> 00:31:53.310 It could be added in. 00:31:53.310 --> 00:31:54.010 There's things-- 00:31:54.010 --> 00:31:57.370 methylation, there's a lot-- yeah, it could be all those 00:31:57.370 --> 00:32:01.680 things, but who's driving that? 00:32:01.680 --> 00:32:03.390 So it's not-- 00:32:03.390 --> 00:32:05.370 my bet is that we'll discover stuff about this that 00:32:05.370 --> 00:32:07.280 we don't grasp yet. 00:32:07.280 --> 00:32:10.600 The answer is not going to be parenting makes no difference, 00:32:10.600 --> 00:32:12.580 or environments make no difference, or schools make no 00:32:12.580 --> 00:32:15.340 difference, for personality. 00:32:15.340 --> 00:32:17.610 But we just don't know how to think about that yet is the 00:32:17.610 --> 00:32:19.870 best guess, because it's just hard to believe. 00:32:19.870 --> 00:32:20.512 Yeah. 00:32:20.512 --> 00:32:23.450 AUDIENCE: Is there a correlation between IQ and any 00:32:23.450 --> 00:32:24.580 kind of personality? 00:32:24.580 --> 00:32:26.030 PROFESSOR: IQ and personality? 00:32:26.030 --> 00:32:27.655 There is a moderate-- 00:32:27.655 --> 00:32:29.460 of conscientiousness especially, 00:32:29.460 --> 00:32:30.490 but that makes sense. 00:32:30.490 --> 00:32:32.110 On average-- 00:32:32.110 --> 00:32:35.650 and we certainly know people who are very smart and very 00:32:35.650 --> 00:32:39.430 sloppy, but on average, the more conscientious you are, 00:32:39.430 --> 00:32:41.580 like if you go to school, you do your homework, that kinds 00:32:41.580 --> 00:32:43.385 of stuff, there is a positive correlation. 00:32:46.630 --> 00:32:48.640 So there's all kinds of-- one question is how much 00:32:48.640 --> 00:32:50.880 personality is fixing your environment. 00:32:50.880 --> 00:32:54.100 So how much is the way you are, from the moment you're 00:32:54.100 --> 00:32:57.000 born, driving actually the way the teacher responds to you in 00:32:57.000 --> 00:32:58.820 school, the way the parent responds to you? 00:32:58.820 --> 00:33:01.310 And so that's why your personality's already driving 00:33:01.310 --> 00:33:03.760 your actual environment. 00:33:03.760 --> 00:33:05.070 Because we could say, well, you're in a school, but 00:33:05.070 --> 00:33:06.952 really, do you like the teacher, do you 00:33:06.952 --> 00:33:07.810 not like the teacher? 00:33:07.810 --> 00:33:09.020 Do you like your parents? 00:33:09.020 --> 00:33:09.820 Do you follow them? 00:33:09.820 --> 00:33:11.100 Do you oppose them? 00:33:11.100 --> 00:33:12.830 Maybe those kinds of things are happening. 00:33:12.830 --> 00:33:18.240 Sometimes people think that your personality is driving 00:33:18.240 --> 00:33:21.010 the way your environment responds to you. 00:33:21.010 --> 00:33:23.480 It might be done by sibling contrast. 00:33:23.480 --> 00:33:25.070 So you may have this experience that-- 00:33:28.740 --> 00:33:31.990 parents and other people and siblings yourself often think 00:33:31.990 --> 00:33:34.140 a fair bit how they are similar or dissimilar from 00:33:34.140 --> 00:33:36.570 their own sibling, and they might overdo it. 00:33:36.570 --> 00:33:39.410 Because a parent has two kids, one kid's like 1% more 00:33:39.410 --> 00:33:43.060 outgoing, and they go, that's the outgoing one. 00:33:43.060 --> 00:33:46.380 One kid plays 5% more time on the piano, and they go, oh, 00:33:46.380 --> 00:33:47.480 she's the real musician. 00:33:47.480 --> 00:33:49.920 And because he plays two more baseball games a year, he's 00:33:49.920 --> 00:33:51.020 the athlete. 00:33:51.020 --> 00:33:54.580 And then it starts to snowball that way, OK? 00:33:54.580 --> 00:33:55.800 Or parent identification. 00:33:55.800 --> 00:33:58.060 Could kids who identify with one parent or the other, 00:33:58.060 --> 00:34:00.770 again, by their predispositions, sort of be 00:34:00.770 --> 00:34:03.500 driving the way their parents interact with them in a way 00:34:03.500 --> 00:34:05.130 that's, again, driven by the personality? 00:34:05.130 --> 00:34:06.070 The personality-- 00:34:06.070 --> 00:34:08.370 from the first moment, for one reason or another-- 00:34:08.370 --> 00:34:11.120 is molding the environment around it and carrying the 00:34:11.120 --> 00:34:13.179 environmental effect as well. 00:34:13.179 --> 00:34:17.310 So one of the giant fights in all of psychology is this. 00:34:17.310 --> 00:34:18.435 And there's not going to be an answer, I'll just 00:34:18.435 --> 00:34:20.550 tell you the debate. 00:34:20.550 --> 00:34:23.020 And it's at the core of this question of why do we do the 00:34:23.020 --> 00:34:25.000 things we do. 00:34:25.000 --> 00:34:26.949 So personality adjusted psychologists will say, it's 00:34:26.949 --> 00:34:28.500 these things we've just discussed. 00:34:28.500 --> 00:34:31.179 It's our predispositions to like things and not like other 00:34:31.179 --> 00:34:33.880 things in a general way are personality. 00:34:33.880 --> 00:34:34.960 Social psychologists-- 00:34:34.960 --> 00:34:37.440 and we'll spend two lectures in just a few weeks on social 00:34:37.440 --> 00:34:37.969 psychology-- 00:34:37.969 --> 00:34:41.730 say people are all kind of the same. 00:34:41.730 --> 00:34:45.870 It's all about the social situation we're in. 00:34:45.870 --> 00:34:48.350 Probably it's like one of these nature-nurture things. 00:34:48.350 --> 00:34:50.270 Probably something about the situation is something about 00:34:50.270 --> 00:34:51.969 who you are. 00:34:51.969 --> 00:34:56.520 But let me tell you how some of this debate is played out. 00:34:56.520 --> 00:35:01.130 So a famous study that went against the idea of a 00:35:01.130 --> 00:35:04.890 personality being constant across situations and time 00:35:04.890 --> 00:35:06.530 came from Walter Mischel. 00:35:06.530 --> 00:35:08.020 And they looked at conscientiousness. 00:35:08.020 --> 00:35:10.710 And they said, OK, some kids score high or low or medium on 00:35:10.710 --> 00:35:12.140 conscientiousness. 00:35:12.140 --> 00:35:16.850 Now, let's look at 19 specific behaviors in their life. 00:35:16.850 --> 00:35:19.170 Not their report of how they are, or their parents' report 00:35:19.170 --> 00:35:21.590 of how they are, but things they do that we can measure. 00:35:21.590 --> 00:35:22.830 How often do they make their bed? 00:35:22.830 --> 00:35:24.410 How often do they go to class like they should? 00:35:24.410 --> 00:35:26.430 How often do they complete their homework assignments? 00:35:26.430 --> 00:35:28.910 How often do they have good class notes 00:35:28.910 --> 00:35:29.730 when they leave classes? 00:35:29.730 --> 00:35:33.310 So things you can check, yes or no. 00:35:33.310 --> 00:35:37.190 And they said gee, what we notice is somebody tends to be 00:35:37.190 --> 00:35:39.310 pretty consistent about whether they make their bed or 00:35:39.310 --> 00:35:41.020 not every morning-- not perfect, but pretty 00:35:41.020 --> 00:35:42.150 consistent. 00:35:42.150 --> 00:35:44.900 But that same person may or may not be so good at 00:35:44.900 --> 00:35:46.150 completing homework assignments. 00:35:48.520 --> 00:35:50.430 And that person that's very consistent on completing 00:35:50.430 --> 00:35:52.920 homework assignments may or may not be so good on having 00:35:52.920 --> 00:35:55.020 neat class notes. 00:35:55.020 --> 00:35:59.590 So it's not that people aren't consistent, but it's far more 00:35:59.590 --> 00:36:02.070 specific about what they're consistent about than a big 00:36:02.070 --> 00:36:04.910 personality dimension that covers a range of things that 00:36:04.910 --> 00:36:05.810 ought to go together. 00:36:05.810 --> 00:36:07.150 So this is situationism. 00:36:07.150 --> 00:36:10.290 You behave in a certain way in a certain situation. 00:36:10.290 --> 00:36:12.200 It's not like you have a personality that moves from 00:36:12.200 --> 00:36:16.300 situation to situation and predicts the same behavior. 00:36:16.300 --> 00:36:18.310 And here's another example of how they follow kids in a 00:36:18.310 --> 00:36:21.890 summer camp, and here's different behaviors from one 00:36:21.890 --> 00:36:23.280 child to another child. 00:36:23.280 --> 00:36:28.310 So this is a child who, when a peer approaches, how verbally 00:36:28.310 --> 00:36:29.600 aggressive they are. 00:36:29.600 --> 00:36:31.180 And so, aggression is high this way. 00:36:31.180 --> 00:36:32.320 These are different situations. 00:36:32.320 --> 00:36:34.160 And you can see for one child they're aggressive in this 00:36:34.160 --> 00:36:36.570 situation when they deal with an adult, and in this 00:36:36.570 --> 00:36:39.530 situation this other child is aggressive when he or she 00:36:39.530 --> 00:36:41.220 deals with a peer. 00:36:41.220 --> 00:36:43.880 So if you were to say there's an aggressive thing about 00:36:43.880 --> 00:36:45.710 people-- they're aggressive or they're not-- well, this 00:36:45.710 --> 00:36:47.890 person's aggressive with a peer, and this person is 00:36:47.890 --> 00:36:51.070 aggressive specifically with an adult. 00:36:51.070 --> 00:36:53.430 And so is aggressiveness a personality thing? 00:36:53.430 --> 00:36:56.430 Or situation by situation by situation? 00:36:56.430 --> 00:36:58.100 In the movies you see all the time-- 00:36:58.100 --> 00:37:01.920 if you watch The Sopranos or many movies, it's not uncommon 00:37:01.920 --> 00:37:05.590 to have the crime figure be really kind of nice with his 00:37:05.590 --> 00:37:10.450 family, and really brutal with a competing criminal gang. 00:37:10.450 --> 00:37:10.600 Right? 00:37:10.600 --> 00:37:13.350 Have you seen that? 00:37:13.350 --> 00:37:15.330 They're kind of nice at home, and then they go shoot people 00:37:15.330 --> 00:37:17.350 on two seconds notice if they're 00:37:17.350 --> 00:37:18.220 fighting about something. 00:37:18.220 --> 00:37:20.700 So you see that kind of an idea. 00:37:24.010 --> 00:37:27.510 Another thing that people have looked at that's related to 00:37:27.510 --> 00:37:28.760 personality is temperament. 00:37:31.560 --> 00:37:33.190 So it's an innate, biologically based propensity 00:37:33.190 --> 00:37:34.900 to engage in a certain style of behavior. 00:37:34.900 --> 00:37:36.050 It's broader than a trait. 00:37:36.050 --> 00:37:39.230 I'll describe one that's been well studied, but people like 00:37:39.230 --> 00:37:40.540 it because they think it's observable. 00:37:40.540 --> 00:37:43.720 So with traits, it's hard to just look at you and say 00:37:43.720 --> 00:37:46.430 you're extroverted or you're conscientious. 00:37:46.430 --> 00:37:48.020 I could follow you around all day and 00:37:48.020 --> 00:37:49.690 maybe have an estimate. 00:37:49.690 --> 00:37:52.830 But here, temperaments are broader than traits, and you 00:37:52.830 --> 00:37:56.050 can see it in terms of people's sociability, 00:37:56.050 --> 00:37:57.680 emotionality and activity level. 00:37:57.680 --> 00:37:59.460 You can just follow them and see them 00:37:59.460 --> 00:38:01.260 behave in certain ways. 00:38:01.260 --> 00:38:03.910 So let's think about the temperament of shyness. 00:38:03.910 --> 00:38:06.350 So the way these studies were done at Harvard was that some 00:38:06.350 --> 00:38:08.240 babies, even at six weeks, are more reactive 00:38:08.240 --> 00:38:09.150 to make sudden noises. 00:38:09.150 --> 00:38:10.410 They're more fussy. 00:38:10.410 --> 00:38:12.620 About 20% of children could be that way. 00:38:12.620 --> 00:38:14.925 They make a noise or something and they cry, they get 00:38:14.925 --> 00:38:16.650 disturbed, they're unhappy. 00:38:16.650 --> 00:38:19.870 And so he called those children high-reactive or 00:38:19.870 --> 00:38:21.610 inhibited babies. 00:38:21.610 --> 00:38:23.120 They use those two terms for the same 00:38:23.120 --> 00:38:24.540 idea, versus low reactive. 00:38:24.540 --> 00:38:26.770 Ones who were very disturbed by the environment, and ones 00:38:26.770 --> 00:38:29.800 who were, like, no big deal. 00:38:29.800 --> 00:38:32.770 And the ones who were inhibited babies cried more, 00:38:32.770 --> 00:38:34.870 they were distressed more, they showed more activity, 00:38:34.870 --> 00:38:38.110 faster heart rates, higher levels of cortisol. 00:38:38.110 --> 00:38:39.720 And they even have-- they could measure this in some 00:38:39.720 --> 00:38:41.440 cases-- faster heart rates in the womb, even 00:38:41.440 --> 00:38:42.790 before they were born. 00:38:42.790 --> 00:38:43.820 Their hearts were racing. 00:38:43.820 --> 00:38:45.750 So all they'd need is that one last little thing. 00:38:45.750 --> 00:38:47.680 And the idea is that maybe their sympathetic nervous 00:38:47.680 --> 00:38:50.360 system is easily aroused, seeks less arousing 00:38:50.360 --> 00:38:53.170 situations, and it's inhibited because they're already 00:38:53.170 --> 00:38:56.700 internally so aroused, they want calm. 00:38:56.700 --> 00:38:59.200 So there's going to be a surprise in this story. 00:38:59.200 --> 00:39:02.830 But as you go, in terms of thinking about shyness, and 00:39:02.830 --> 00:39:04.780 you can measure these at two months or four months with 00:39:04.780 --> 00:39:06.660 these very simple little things you do with babies to 00:39:06.660 --> 00:39:09.020 see how they respond to some noise. 00:39:09.020 --> 00:39:11.580 And to a decent extent, it predicts shyness in later 00:39:11.580 --> 00:39:13.140 childhood and adulthood. 00:39:13.140 --> 00:39:15.780 About a quarter of the children who look pretty 00:39:15.780 --> 00:39:19.990 inhibited aren't shy, but about 75% who look pretty 00:39:19.990 --> 00:39:21.480 inhibited end up shy. 00:39:21.480 --> 00:39:23.230 So that's a pretty good prediction from a 00:39:23.230 --> 00:39:25.290 two-month-old to a young adult. 00:39:25.290 --> 00:39:27.330 About 75% of these children who look 00:39:27.330 --> 00:39:29.800 pretty shy at two months-- 00:39:29.800 --> 00:39:31.440 and of course, they're not shy in a group, they're just 00:39:31.440 --> 00:39:32.970 responding to noises-- 00:39:32.970 --> 00:39:35.040 end up being kind of shy as adults. 00:39:38.740 --> 00:39:44.000 And they studied these until age 21, and again, in several 00:39:44.000 --> 00:39:49.530 outcomes, specifically things like-- let's pick one-- 00:39:49.530 --> 00:39:51.240 crime, how often they get in crime. 00:39:51.240 --> 00:39:54.270 Children who are well controlled don't get so much 00:39:54.270 --> 00:39:54.740 into crime. 00:39:54.740 --> 00:39:59.410 Children who at 21 had poor control at age three are more 00:39:59.410 --> 00:40:00.650 likely to get into trouble. 00:40:00.650 --> 00:40:04.130 So as if these temperament factors in early, early 00:40:04.130 --> 00:40:07.420 childhood are already risk factors for doing better or 00:40:07.420 --> 00:40:10.610 worse in the world. 00:40:10.610 --> 00:40:14.320 Another one that people enjoy studying is sensation seeking. 00:40:14.320 --> 00:40:17.130 You know, the bungee jumpers, the people who like to 00:40:17.130 --> 00:40:20.770 parachute, people who enjoy the thrill of activities, 00:40:20.770 --> 00:40:23.160 novel, high-stimulation situations. 00:40:23.160 --> 00:40:26.920 Statistically they have more fun, probably, in some ways. 00:40:26.920 --> 00:40:29.070 They're more likely to dive, they're more likely to drive 00:40:29.070 --> 00:40:31.100 fast, they're more likely to have drug or alcohol use, 00:40:31.100 --> 00:40:32.900 they're more likely to send flame emails, listen to punk 00:40:32.900 --> 00:40:34.260 music, and have driving accidents. 00:40:34.260 --> 00:40:38.460 So it's an interesting mix of enjoyment and trouble. 00:40:38.460 --> 00:40:41.540 And there's some evidence they have lower levels of something 00:40:41.540 --> 00:40:44.740 in the blood that may be a measure of something that lets 00:40:44.740 --> 00:40:47.710 dopamine last longer in the synapse in your brain. 00:40:47.710 --> 00:40:50.800 Dopamine is the reward neurotransmitter. 00:40:50.800 --> 00:40:54.330 So you could imagine that if the reward hangs around 00:40:54.330 --> 00:40:56.820 longer, maybe you're more drawn towards instantly 00:40:56.820 --> 00:40:59.750 rewarding things. 00:40:59.750 --> 00:41:04.745 Another sort of, I think, two-dimensional classification 00:41:04.745 --> 00:41:06.060 of personality. 00:41:06.060 --> 00:41:08.790 Again, one dimension that he focused on was this 00:41:08.790 --> 00:41:11.620 introversion to extroversion or stable to unstable. 00:41:11.620 --> 00:41:14.600 This is neuroticism or introversion/extroversion in 00:41:14.600 --> 00:41:16.280 the big five. 00:41:16.280 --> 00:41:18.220 But there's some interesting turns on this. 00:41:18.220 --> 00:41:19.160 Here's the interesting turn. 00:41:19.160 --> 00:41:20.380 I mentioned it, but let me tell you one more time, 00:41:20.380 --> 00:41:22.250 because it's counter-intuitive. 00:41:22.250 --> 00:41:24.120 It's the opposite of what you think in terms of what people 00:41:24.120 --> 00:41:25.390 have found. 00:41:25.390 --> 00:41:27.860 So we think of extroverts as people who go to parties, are 00:41:27.860 --> 00:41:30.620 very talkative, very outgoing, run around and have a social 00:41:30.620 --> 00:41:33.390 time, and introverts as more likely to be shy, quiet, 00:41:33.390 --> 00:41:33.940 withdrawn, right? 00:41:33.940 --> 00:41:36.920 That's the definitions of the words. 00:41:36.920 --> 00:41:39.495 But what people have found in a variety of studies is that 00:41:39.495 --> 00:41:40.310 extroverts-- the outgoing people-- 00:41:40.310 --> 00:41:42.710 are less easily aroused. 00:41:42.710 --> 00:41:44.020 So it's as if they seek stimulation. 00:41:44.020 --> 00:41:48.110 It's as if their internal arousal is low, and they want 00:41:48.110 --> 00:41:50.280 things that are stimulating in their environment to push up 00:41:50.280 --> 00:41:52.400 their internal arousal, right? 00:41:52.400 --> 00:41:54.170 Introverts are the opposite around. 00:41:54.170 --> 00:41:57.460 Introverts are aroused already, and it's as if they 00:41:57.460 --> 00:42:00.780 seek environments that are quiet, so their arousal is not 00:42:00.780 --> 00:42:02.820 pushed above some level of discomfort. 00:42:02.820 --> 00:42:05.120 So intuitively you might think extroverts are more aroused 00:42:05.120 --> 00:42:10.530 internally, but the thought is that extroverts are actually 00:42:10.530 --> 00:42:14.170 seeking arousal because they're a little lower inside. 00:42:14.170 --> 00:42:16.800 Introverts are already feeling pretty aroused, so they don't 00:42:16.800 --> 00:42:19.630 need more bungee jumping. 00:42:19.630 --> 00:42:22.690 They're already feeling like they're bungee jumping, OK? 00:42:22.690 --> 00:42:24.760 So then they're all seeking this sort of 00:42:24.760 --> 00:42:26.260 optimal level of arousal. 00:42:26.260 --> 00:42:29.070 So, for example, extroverts do better in noisy settings, they 00:42:29.070 --> 00:42:32.900 can take the extra stuff, they don't mind it. 00:42:32.900 --> 00:42:35.820 Introverts are more sensitive to pain, and they salivate 00:42:35.820 --> 00:42:36.700 more to lemon juice. 00:42:36.700 --> 00:42:41.570 They're already kind of revved up, is the story, internally. 00:42:41.570 --> 00:42:43.730 So here's one-- 00:42:43.730 --> 00:42:46.560 we couldn't do this early in the course, and this almost 00:42:46.560 --> 00:42:48.420 has practical concept-- 00:42:48.420 --> 00:42:51.040 you could think about this for your own test taking. 00:42:51.040 --> 00:42:53.025 A three-way interaction. 00:42:53.025 --> 00:42:55.690 This is three factors that all interact with one another in 00:42:55.690 --> 00:42:58.790 performance, and it involves situation and personality. 00:42:58.790 --> 00:42:59.970 So here we go. 00:42:59.970 --> 00:43:01.840 So the three factors are whether you're introverted or 00:43:01.840 --> 00:43:05.540 extroverted, whether you're taking a test-- a GRE kind of 00:43:05.540 --> 00:43:08.610 a test-- in the morning or the afternoon, and whether you 00:43:08.610 --> 00:43:11.390 drank a cup of coffee before the test or not. 00:43:11.390 --> 00:43:14.160 Three different things floating around. 00:43:14.160 --> 00:43:16.010 And here's what people have found several times in 00:43:16.010 --> 00:43:18.920 experiments when you're taking a test. 00:43:18.920 --> 00:43:20.840 Here's the upshot of the studies. 00:43:20.840 --> 00:43:25.180 If you're introverted and the test is in the late afternoon 00:43:25.180 --> 00:43:27.210 or evening, drink coffee. 00:43:27.210 --> 00:43:30.230 If you're outgoing, drink coffee in the morning. 00:43:30.230 --> 00:43:32.820 And I'll tell you the logic of this. 00:43:32.820 --> 00:43:35.500 All right? 00:43:35.500 --> 00:43:37.140 So here's the idea. 00:43:37.140 --> 00:43:39.190 Many studies have shown-- and you may know this, if you 00:43:39.190 --> 00:43:41.250 think about people you know or yourself. 00:43:41.250 --> 00:43:43.630 On average, introverts are most aroused in the morning. 00:43:43.630 --> 00:43:45.240 They tend to be get up early in the morning and get their 00:43:45.240 --> 00:43:46.430 day going people. 00:43:46.430 --> 00:43:48.310 Maybe because they didn't party deep into 00:43:48.310 --> 00:43:50.400 the previous night. 00:43:50.400 --> 00:43:52.345 There's cause and effect that's really hard to pull out 00:43:52.345 --> 00:43:54.520 in all of this. 00:43:54.520 --> 00:43:56.340 But introverts are more aroused in the morning and 00:43:56.340 --> 00:43:57.620 less in the evening. 00:43:57.620 --> 00:43:59.206 On average, they're the kind of people who are get up early 00:43:59.206 --> 00:44:00.500 in the morning, go do their stuff. 00:44:00.500 --> 00:44:03.450 In the evening they want to mellow down and maybe not go 00:44:03.450 --> 00:44:04.450 to sleep so late. 00:44:04.450 --> 00:44:06.590 Extroverts are more aroused in the evening, 00:44:06.590 --> 00:44:07.810 and less in the morning. 00:44:07.810 --> 00:44:09.300 And this is on average, and this has been 00:44:09.300 --> 00:44:10.650 found a number of times. 00:44:10.650 --> 00:44:13.050 So again, you can imagine if you're taking a test, if 00:44:13.050 --> 00:44:16.040 you're under-aroused, you could use the 00:44:16.040 --> 00:44:17.070 coffee to perk you up. 00:44:17.070 --> 00:44:18.830 If you're over-aroused, the coffee is going to make you 00:44:18.830 --> 00:44:20.470 jittery and push you over. 00:44:20.470 --> 00:44:22.260 So depending on the time of day, you're going to be in one 00:44:22.260 --> 00:44:23.430 state or the other depending on the kind of 00:44:23.430 --> 00:44:24.190 personality you have. 00:44:24.190 --> 00:44:24.710 Does that make sense? 00:44:24.710 --> 00:44:28.070 These three things come together like that in the 00:44:28.070 --> 00:44:30.660 famous Yerkes-Dodson Law of performance, which is this. 00:44:30.660 --> 00:44:33.030 And this is observed in many years. 00:44:33.030 --> 00:44:34.830 Here's arousal, how aroused you are. 00:44:34.830 --> 00:44:39.030 Super aroused, super nervous, shaky, so sleepy you're about 00:44:39.030 --> 00:44:41.110 to crash out. 00:44:41.110 --> 00:44:42.540 Somewhere in the middle usually goes with best 00:44:42.540 --> 00:44:46.130 performance, because this is too much, 00:44:46.130 --> 00:44:46.950 and this is too little. 00:44:46.950 --> 00:44:47.630 You know that. 00:44:47.630 --> 00:44:49.900 If you're too nervous, you don't tend to perform well. 00:44:49.900 --> 00:44:52.760 If you're too kind of out of it, you don't perform well. 00:44:52.760 --> 00:44:55.830 Somewhere in the middle is just right. 00:44:55.830 --> 00:44:58.690 So here's extroverts, for example. 00:44:58.690 --> 00:45:02.460 In the morning, they're pretty low on this, they could use 00:45:02.460 --> 00:45:04.860 some coffee to move to optimal. 00:45:04.860 --> 00:45:06.976 Here's introverts in the morning, they're already ready 00:45:06.976 --> 00:45:08.720 to go, I'm ready to go, I'm ready to go. 00:45:08.720 --> 00:45:11.820 The last thing they need is more coffee. 00:45:11.820 --> 00:45:14.520 I hope it's not a bubble test because my hands are shaking. 00:45:14.520 --> 00:45:15.050 OK? 00:45:15.050 --> 00:45:17.490 So three things. 00:45:17.490 --> 00:45:20.450 The kind of personality you are, the time of day, and 00:45:20.450 --> 00:45:22.920 whether your drinking coffee helps you to move to this 00:45:22.920 --> 00:45:23.880 middle position or not. 00:45:23.880 --> 00:45:25.420 Does that makes sense? 00:45:25.420 --> 00:45:27.760 So that's three different factors sort of adding up to 00:45:27.760 --> 00:45:30.120 optimize performance or not. 00:45:30.120 --> 00:45:33.390 OK, lastly I'd like to talk a little bit about some things 00:45:33.390 --> 00:45:37.400 we know about brain correlates of personality. 00:45:37.400 --> 00:45:42.480 And in some areas, these brain things are more informative at 00:45:42.480 --> 00:45:43.490 a broad level. 00:45:43.490 --> 00:45:45.420 Because sometimes people will say, well, personality is all 00:45:45.420 --> 00:45:46.900 this check box stuff. 00:45:46.900 --> 00:45:48.830 Is it even relevant to anything biological? 00:45:48.830 --> 00:45:50.900 Now, if it's relevant to behavior, 00:45:50.900 --> 00:45:52.370 it's relevant to biology. 00:45:52.370 --> 00:45:56.140 Behavior is biology, or biology is behavior. 00:45:56.140 --> 00:45:57.650 We're not going to get one relative to the other. 00:45:57.650 --> 00:46:00.490 But still, until recently, people couldn't measure this. 00:46:00.490 --> 00:46:01.780 So these are pictures of-- 00:46:01.780 --> 00:46:04.530 not of brain functions, of a task turning on-- we'll see 00:46:04.530 --> 00:46:05.920 pictures of those in a moment. 00:46:05.920 --> 00:46:09.510 This is measurement of brain structure. 00:46:09.510 --> 00:46:11.880 Measurement of brain structure. 00:46:11.880 --> 00:46:15.470 And specifically, thickness of cortex. 00:46:15.470 --> 00:46:17.920 So what you're seeing is a statistic here, which is, the 00:46:17.920 --> 00:46:20.710 more extroverted you are, the thicker your cortex is here. 00:46:20.710 --> 00:46:23.740 The more conscientious, the thicker your cortex here. 00:46:23.740 --> 00:46:28.700 The more neurotic, the thicker your cortex here, and so on. 00:46:28.700 --> 00:46:31.720 So we don't understand these deeply, but we do see 00:46:31.720 --> 00:46:34.130 physically measurable correlates of these 00:46:34.130 --> 00:46:36.250 personality dimensions. 00:46:36.250 --> 00:46:38.500 So that's physical brain structure. 00:46:38.500 --> 00:46:40.090 Let's talk about some function things. 00:46:40.090 --> 00:46:44.370 This is a slide you saw before that in the amygdala, the more 00:46:44.370 --> 00:46:46.960 emotionally intense something is, the more the response. 00:46:46.960 --> 00:46:50.890 The more neutral it is, the less the response. 00:46:50.890 --> 00:46:53.170 Here's a positive happy picture, right? 00:46:53.170 --> 00:46:54.140 I'm going to show you a neutral picture. 00:46:54.140 --> 00:46:56.140 I'm going to show you now the bad picture. 00:46:56.140 --> 00:46:57.470 Don't look if you don't want to see it again. 00:46:57.470 --> 00:46:58.260 It's the one you saw before. 00:46:58.260 --> 00:46:59.250 Close your eyes for a moment. 00:46:59.250 --> 00:46:59.850 Bad picture. 00:46:59.850 --> 00:47:00.010 OK. 00:47:00.010 --> 00:47:00.580 Here we go. 00:47:00.580 --> 00:47:01.940 Now you can all look. 00:47:01.940 --> 00:47:04.990 So people are introverted or extroverted. 00:47:04.990 --> 00:47:07.560 Extroverts are sociable, talkative. 00:47:07.560 --> 00:47:11.020 Introverts are, on average, more reserved or quiet. 00:47:11.020 --> 00:47:14.150 Extroverts report more positive experiences, more 00:47:14.150 --> 00:47:16.120 susceptible to positive mood induction. 00:47:16.120 --> 00:47:18.440 Lots of evidence for some differences among them. 00:47:18.440 --> 00:47:20.520 So imagine a study where you show people positive and 00:47:20.520 --> 00:47:21.320 negative slides. 00:47:21.320 --> 00:47:24.510 Again, people will say, well, if I'm on a diet, this is 00:47:24.510 --> 00:47:28.230 really negative, or something. 00:47:28.230 --> 00:47:29.090 You have people rate them. 00:47:29.090 --> 00:47:30.760 But on average these are negative, and on average these 00:47:30.760 --> 00:47:32.790 are positive. 00:47:32.790 --> 00:47:36.120 You measure their personality, and here's what you find in 00:47:36.120 --> 00:47:37.370 the amygdala. 00:47:39.170 --> 00:47:43.590 The more extroverted they are, the more their amygdala 00:47:43.590 --> 00:47:46.060 responds to positive things. 00:47:46.060 --> 00:47:48.480 The more introverted they are, the more it responds to 00:47:48.480 --> 00:47:50.830 negative things. 00:47:50.830 --> 00:47:53.390 So here's exactly what we mean by personality sort of 00:47:53.390 --> 00:47:54.220 instantiated in one example. 00:47:54.220 --> 00:47:55.990 And it's not the only example. 00:47:55.990 --> 00:47:57.030 What do we mean by personality? 00:47:57.030 --> 00:47:59.370 We mean there's a constant situation-- 00:47:59.370 --> 00:48:01.760 let's pretend a party you go to. 00:48:01.760 --> 00:48:03.090 A party deep in my memory. 00:48:03.090 --> 00:48:05.310 I remember parties I went to, the music is playing, and 00:48:05.310 --> 00:48:07.930 there's sticky beer on the floor, and there's people you 00:48:07.930 --> 00:48:09.590 know and a lot of people you don't know, right? 00:48:09.590 --> 00:48:12.810 So who walks in the door and thinks this is awesome? 00:48:12.810 --> 00:48:14.230 The extrovert, right? 00:48:14.230 --> 00:48:17.240 Who walks in the door and thinks why did my friend drag 00:48:17.240 --> 00:48:17.720 me to this? 00:48:17.720 --> 00:48:20.500 I could be doing something good like chess at home. 00:48:23.090 --> 00:48:26.270 So now, identical situation, different-- but that's true of 00:48:26.270 --> 00:48:27.970 so many things and preferences in life. 00:48:27.970 --> 00:48:29.950 That's almost what we mean by personality, right? 00:48:29.950 --> 00:48:31.750 Who likes what? 00:48:31.750 --> 00:48:34.020 Situations, people, activities. 00:48:34.020 --> 00:48:38.230 So for extroversion, here's the amygdala going, positive 00:48:38.230 --> 00:48:39.410 things, whoopee! 00:48:39.410 --> 00:48:42.620 They notice, so to speak, in their amygdala the positivity 00:48:42.620 --> 00:48:43.210 of the environment. 00:48:43.210 --> 00:48:45.250 They're drawn to things because they see positive. 00:48:45.250 --> 00:48:47.850 Here is the introverts going, danger, danger. 00:48:47.850 --> 00:48:48.570 OK? 00:48:48.570 --> 00:48:51.030 Everybody sees the same set of slides, but people are drawn 00:48:51.030 --> 00:48:53.580 to the positive or the negative aspects of this. 00:48:53.580 --> 00:48:54.850 And you could say, is one better, the other worse? 00:48:54.850 --> 00:48:55.710 Well, no. 00:48:55.710 --> 00:48:58.110 Avoiding dangerous things is a good idea. 00:48:58.110 --> 00:49:00.130 Enjoying positive things is a good idea. 00:49:00.130 --> 00:49:01.830 One is not better than the other. 00:49:01.830 --> 00:49:02.850 They're just different. 00:49:02.850 --> 00:49:05.570 You're tuned to different rewards in life. 00:49:05.570 --> 00:49:07.490 And this is one example of that. 00:49:07.490 --> 00:49:09.440 How about a smiling face? 00:49:09.440 --> 00:49:12.610 Who thinks a smiling face is an invitation to go over and 00:49:12.610 --> 00:49:13.290 meet somebody new? 00:49:13.290 --> 00:49:15.760 The introvert or the extrovert? 00:49:15.760 --> 00:49:16.646 Help me on this. 00:49:16.646 --> 00:49:18.820 Who thinks the smiling face is pressure? 00:49:18.820 --> 00:49:19.770 Do I go over? 00:49:19.770 --> 00:49:21.020 Are they smiling at me? 00:49:23.696 --> 00:49:25.450 Or I'm going to go over and then they're 00:49:25.450 --> 00:49:26.700 not gonna like me. 00:49:26.700 --> 00:49:28.260 They like me now, right? 00:49:28.260 --> 00:49:31.220 I should tell you, I was quite-- 00:49:31.220 --> 00:49:33.920 only in my teaching mode do I appear extroverted, OK? 00:49:33.920 --> 00:49:35.310 But I definitely was an introvert in 00:49:35.310 --> 00:49:36.550 high school and college. 00:49:36.550 --> 00:49:38.080 So if I make fun of introverts, I'm 00:49:38.080 --> 00:49:40.820 making fun of myself. 00:49:40.820 --> 00:49:43.970 So here's a response to fearful faces. 00:49:43.970 --> 00:49:45.910 And we talked about that before, response in the 00:49:45.910 --> 00:49:48.040 amygdala regardless of personality. 00:49:48.040 --> 00:49:50.700 But now when we talk about the response in the amygdala for 00:49:50.700 --> 00:49:55.070 happy faces, big response if you're extroverted, little 00:49:55.070 --> 00:49:56.790 response if you're introverted. 00:49:56.790 --> 00:49:59.630 Because a happy face is like compelling, cool, wonderful 00:49:59.630 --> 00:50:04.780 for the extrovert, and not as enticing for the introvert. 00:50:04.780 --> 00:50:07.670 So again, the way we might imagine, how do individual 00:50:07.670 --> 00:50:08.980 differences in personality play out? 00:50:08.980 --> 00:50:12.130 They play out that some things are beguiling, wonderful, and 00:50:12.130 --> 00:50:13.070 other things not so much. 00:50:13.070 --> 00:50:15.652 And depending on your personality, that can vary. 00:50:19.350 --> 00:50:22.620 So these are the children who were studied from the ages of 00:50:22.620 --> 00:50:29.130 two and four months who were shy in temperament, 00:50:29.130 --> 00:50:30.700 inhibited, in orange. 00:50:30.700 --> 00:50:33.035 And they compared them to the most uninhibited. 00:50:33.035 --> 00:50:34.680 They take the extremes. 00:50:34.680 --> 00:50:36.950 But it's a very rare thing when you have a behavioral 00:50:36.950 --> 00:50:40.770 assessment of a child in their infancy, and then you brain 00:50:40.770 --> 00:50:44.950 image them about 20 years later when they're grown up. 00:50:44.950 --> 00:50:48.440 So now you're making this 20 years of your life story, and 00:50:48.440 --> 00:50:51.380 again in the amygdala, what they find is this. 00:50:51.380 --> 00:50:56.080 If you look at the people who are uninhibited, here's a 00:50:56.080 --> 00:50:58.570 novel face they see for the first time in the scanner, or 00:50:58.570 --> 00:51:00.440 a face they've seen many times, and there's not much 00:51:00.440 --> 00:51:01.770 difference. 00:51:01.770 --> 00:51:03.380 For the people who are inhibited, you see a much 00:51:03.380 --> 00:51:05.990 bigger amygdala response to the novel face. 00:51:05.990 --> 00:51:08.130 Well, this is exactly what you might intuitively think 00:51:08.130 --> 00:51:09.930 shyness would be about. 00:51:09.930 --> 00:51:12.490 If you're a shy person and you know somebody well, I think a 00:51:12.490 --> 00:51:14.440 lot of shyness disappears. 00:51:14.440 --> 00:51:17.460 But where shyness shows the most is a face that you don't 00:51:17.460 --> 00:51:20.560 know, a new person you haven't met, and maybe you're not so 00:51:20.560 --> 00:51:22.290 comfortable with them yet. 00:51:22.290 --> 00:51:25.300 So this is exactly the pattern you might expect, that it 00:51:25.300 --> 00:51:27.470 doesn't matter too much for an extrovert, a new face, a 00:51:27.470 --> 00:51:28.910 familiar face-- 00:51:28.910 --> 00:51:30.635 made familiar in the experiment, not somebody you 00:51:30.635 --> 00:51:31.470 really know-- 00:51:31.470 --> 00:51:33.230 it doesn't make much of a difference. 00:51:33.230 --> 00:51:35.825 For the person who is inhibited, much more response 00:51:35.825 --> 00:51:38.585 to the face they see for the first time only, as opposed to 00:51:38.585 --> 00:51:42.275 a face they've grown familiar with. 00:51:42.275 --> 00:51:45.130 A couple more examples along this line. 00:51:45.130 --> 00:51:46.010 Here's another scale. 00:51:46.010 --> 00:51:47.550 There's an infinite number of them. 00:51:47.550 --> 00:51:50.340 The Spielberger State and Trait Anxiety, so, state and 00:51:50.340 --> 00:51:50.980 trait, right? 00:51:50.980 --> 00:51:53.720 So they ask you-- this is just a reminder of that-- 00:51:53.720 --> 00:51:54.750 how do you feel right now? 00:51:54.750 --> 00:51:55.520 That would be your state. 00:51:55.520 --> 00:51:56.210 Right now. 00:51:56.210 --> 00:51:57.280 Do I feel at ease? 00:51:57.280 --> 00:51:58.400 Do I feel upset? 00:51:58.400 --> 00:52:00.770 And in general, how do you feel, at ease or upset? 00:52:00.770 --> 00:52:04.100 So this is day in day out, this is right now. 00:52:04.100 --> 00:52:07.200 We're going to focus on the trait, how you say you feel 00:52:07.200 --> 00:52:08.810 day in, day out. 00:52:08.810 --> 00:52:12.630 And now they're going to show you faces of people who are 00:52:12.630 --> 00:52:17.020 shown in full view, or who are shown in a subliminal masked 00:52:17.020 --> 00:52:19.000 version where a fear or neutral face is followed by 00:52:19.000 --> 00:52:19.730 another face. 00:52:19.730 --> 00:52:21.010 This is the critical face. 00:52:21.010 --> 00:52:24.060 So you see a face that you see pretty well, or you see a face 00:52:24.060 --> 00:52:26.310 that's presented under circumstances where you can't 00:52:26.310 --> 00:52:28.820 tell what the face was. 00:52:28.820 --> 00:52:29.880 OK? 00:52:29.880 --> 00:52:32.210 At first they say, what happens if we show you the 00:52:32.210 --> 00:52:34.720 regular face that you see perfectly well? 00:52:34.720 --> 00:52:35.850 Nothing makes much of a difference. 00:52:35.850 --> 00:52:37.550 Here's the amygdala response to fearful face. 00:52:37.550 --> 00:52:39.980 You've seen this now multiple times. 00:52:39.980 --> 00:52:42.620 But kind of interestingly, you get a smaller response in the 00:52:42.620 --> 00:52:46.600 amygdala, and it's driven by how anxious you report 00:52:46.600 --> 00:52:49.150 yourself to be on a regular basis. 00:52:49.150 --> 00:52:51.630 So the interpretation is this. 00:52:51.630 --> 00:52:53.930 If you see a fearful face, you go, well, it's a fearful face, 00:52:53.930 --> 00:52:56.620 I know it's a fearful phase, we're all the same. 00:52:56.620 --> 00:52:59.190 If you subliminally present it, you have an 00:52:59.190 --> 00:53:02.080 unknown source of danger. 00:53:02.080 --> 00:53:07.030 What we intuitively imagine anxiety is is feeling danger 00:53:07.030 --> 00:53:10.600 or threat in your environment more than is helpful, more 00:53:10.600 --> 00:53:11.950 than is comfortable. 00:53:11.950 --> 00:53:12.700 OK? 00:53:12.700 --> 00:53:14.330 And you don't even know exactly why. 00:53:14.330 --> 00:53:16.040 It's not entirely rational when you're 00:53:16.040 --> 00:53:17.790 anxious in that way. 00:53:17.790 --> 00:53:20.350 And so what happens is, the more anxious you are, the more 00:53:20.350 --> 00:53:24.120 these subliminal faces drive an amygdala response, and you 00:53:24.120 --> 00:53:26.010 don't have control over that, because you don't know what 00:53:26.010 --> 00:53:27.910 happened, because it was subliminally presented. 00:53:27.910 --> 00:53:29.040 Does that make sense? 00:53:29.040 --> 00:53:31.340 When it's clear, everybody knows what to do. 00:53:31.340 --> 00:53:33.740 It's just a face and not that scary. 00:53:33.740 --> 00:53:36.630 But when it's an unknown source of a bit of unease, the 00:53:36.630 --> 00:53:39.430 more chronically anxious you are, the more the brain's 00:53:39.430 --> 00:53:39.910 responding. 00:53:39.910 --> 00:53:42.420 Or we might say, the bigger the brain response is the 00:53:42.420 --> 00:53:47.270 basis, perhaps, of the chronic unease. 00:53:47.270 --> 00:53:49.710 So we talked also before about the amygdala being important 00:53:49.710 --> 00:53:53.050 for recognizing fearful expressions. 00:53:53.050 --> 00:53:56.340 And then I want to share two last examples. 00:53:56.340 --> 00:53:57.800 How about genetic influences? 00:53:57.800 --> 00:54:00.280 So we know genes are a big part of the story, but how big 00:54:00.280 --> 00:54:00.970 a part of the story? 00:54:00.970 --> 00:54:02.840 So again, we talked about single nucleotide 00:54:02.840 --> 00:54:06.330 polymorphisms, common genetic variance. 00:54:06.330 --> 00:54:08.450 And here's one that involves a serotonin 00:54:08.450 --> 00:54:10.830 transporter in the amygdala. 00:54:10.830 --> 00:54:15.380 There's a short or long allele, so we'll have two of 00:54:15.380 --> 00:54:16.660 these, all of us. 00:54:16.660 --> 00:54:19.650 The short allele is weakly correlated 00:54:19.650 --> 00:54:20.930 with anxiety traits. 00:54:20.930 --> 00:54:23.890 All this genetic stuff is pretty weak at the moment, for 00:54:23.890 --> 00:54:25.830 reasons that are not well understood. 00:54:25.830 --> 00:54:27.630 I'm only presenting you ones that have been at least 00:54:27.630 --> 00:54:28.780 replicated once. 00:54:28.780 --> 00:54:31.070 But practically every genetic example I'm going to show you, 00:54:31.070 --> 00:54:33.190 there's been non-confirmations as well. 00:54:33.190 --> 00:54:34.740 We don't know why this is. 00:54:34.740 --> 00:54:37.410 The genes are just so far away from complex human behaviors 00:54:37.410 --> 00:54:38.950 is probably the answer. 00:54:38.950 --> 00:54:41.710 But what has been replicated a number of times is this. 00:54:41.710 --> 00:54:45.200 If they show you fearful faces, and you have the short 00:54:45.200 --> 00:54:47.160 allele, the one that's slightly associated with 00:54:47.160 --> 00:54:50.145 anxiety, this is the difference between people with 00:54:50.145 --> 00:54:51.730 the long allele and the shorter allele, a much more 00:54:51.730 --> 00:54:54.910 powerful response to fearful faces if you 00:54:54.910 --> 00:54:55.790 have the shorter allele. 00:54:55.790 --> 00:54:58.470 So a single gene can be correlated with a more potent 00:54:58.470 --> 00:55:01.060 response to a sort of threat stimulus. 00:55:01.060 --> 00:55:03.550 And again, that goes with our sense of anxiety, and what we 00:55:03.550 --> 00:55:06.610 might call a less than desirable response to threat 00:55:06.610 --> 00:55:08.810 in the environment. 00:55:08.810 --> 00:55:12.410 So here's the last two slides. 00:55:12.410 --> 00:55:17.430 But it's the dream we all have in understanding people, and 00:55:17.430 --> 00:55:19.470 actually all animals on the face of this planet, but 00:55:19.470 --> 00:55:22.120 people most of all if you're curious about people, which 00:55:22.120 --> 00:55:25.380 is, what is the interaction between the genes we're born 00:55:25.380 --> 00:55:27.730 with and the life we lead, and how does that end up 00:55:27.730 --> 00:55:29.480 with us being us? 00:55:29.480 --> 00:55:32.950 And it's incredibly hard to study that, because everybody 00:55:32.950 --> 00:55:37.350 says in biology and neuroscience, we know it's a 00:55:37.350 --> 00:55:39.780 gene by experience interaction. 00:55:39.780 --> 00:55:43.020 The genes will make you strong in some circumstances and 00:55:43.020 --> 00:55:44.850 vulnerable in others. 00:55:44.850 --> 00:55:46.530 But it's very hard to specify that. 00:55:46.530 --> 00:55:48.590 The genes have been hard to identify. 00:55:48.590 --> 00:55:50.610 And we can't put people into experiments. 00:55:50.610 --> 00:55:53.340 We can't say, we'll take two identical twins and we'll put 00:55:53.340 --> 00:55:56.290 one into some horrible household full of stress and 00:55:56.290 --> 00:55:58.720 horribleness, and then one into a delightful household, 00:55:58.720 --> 00:56:00.730 and then see them at 20 and see what happened. 00:56:00.730 --> 00:56:01.210 OK? 00:56:01.210 --> 00:56:02.440 We're just not allowed to do that, right? 00:56:02.440 --> 00:56:06.620 So we can't experiment on the environment, and the genes are 00:56:06.620 --> 00:56:11.040 poorly understood, very poorly understood, in relation to 00:56:11.040 --> 00:56:12.850 basic human behaviors. 00:56:12.850 --> 00:56:15.630 But there's a study from Caspi that is a glimpse of where we 00:56:15.630 --> 00:56:16.730 think the field might be going. 00:56:16.730 --> 00:56:19.200 But I'm going to warn you that this has not always been 00:56:19.200 --> 00:56:20.520 replicated. 00:56:20.520 --> 00:56:22.150 It's been replicated sometimes, 00:56:22.150 --> 00:56:22.940 but not other times. 00:56:22.940 --> 00:56:26.700 So it's an asterisk, but it's still a finding that's really 00:56:26.700 --> 00:56:29.790 quite striking, if it turns out to be roughly correct. 00:56:29.790 --> 00:56:32.800 So again, this is polymorphism of the same gene that's 00:56:32.800 --> 00:56:34.880 associated with anxiety. 00:56:34.880 --> 00:56:37.870 And what they did in a very large sample in New Zealand 00:56:37.870 --> 00:56:46.040 was catalog stressful life events ages 21 to 26, job, 00:56:46.040 --> 00:56:48.820 whether you have a job or not, your salary, decent housing, 00:56:48.820 --> 00:56:50.950 terrible housing, good health, bad health, happy 00:56:50.950 --> 00:56:52.830 relationships, no relationships, terrible 00:56:52.830 --> 00:56:53.480 relationships. 00:56:53.480 --> 00:56:55.940 People are filling out forms telling you about the stresses 00:56:55.940 --> 00:56:57.530 in their life. 00:56:57.530 --> 00:57:00.830 And then they also have information about childhood 00:57:00.830 --> 00:57:01.380 maltreatment. 00:57:01.380 --> 00:57:04.700 Some of these children, very sadly, when they were younger 00:57:04.700 --> 00:57:07.080 were treated very poorly, they were abused in some way or 00:57:07.080 --> 00:57:10.610 another, were in very terrible circumstances, and some not. 00:57:10.610 --> 00:57:12.920 So they're going to look at stressful events in childhood 00:57:12.920 --> 00:57:18.350 and adulthood, and sort them out by the allele that the 00:57:18.350 --> 00:57:21.720 individuals have, the gene version, and what they find 00:57:21.720 --> 00:57:23.360 is-- and I'll show you the graph in a moment-- 00:57:23.360 --> 00:57:25.680 more depression and suicidality in response to 00:57:25.680 --> 00:57:29.310 stressful events if you have a short version of the allele. 00:57:29.310 --> 00:57:31.650 The short version, we just said, is the one that seems to 00:57:31.650 --> 00:57:35.025 drive a bigger anxiety response to fearful faces in 00:57:35.025 --> 00:57:36.220 the amygdala, OK? 00:57:36.220 --> 00:57:40.570 So it seems, first pass, to be a gene that's associated with 00:57:40.570 --> 00:57:45.120 responding in a more anxious way to environmental stress, 00:57:45.120 --> 00:57:47.810 threat, and bad things. 00:57:47.810 --> 00:57:49.010 So here's a couple of graphs. 00:57:49.010 --> 00:57:50.430 I'll just do a couple with you. 00:57:50.430 --> 00:57:55.170 Here's the probability of major depression if you've had 00:57:55.170 --> 00:57:59.130 no maltreatment as a child, if you've probably had some, or 00:57:59.130 --> 00:58:02.650 you've had documented horrible maltreatment as a child. 00:58:02.650 --> 00:58:04.920 And what you can see if you have the long version-- this 00:58:04.920 --> 00:58:06.070 is this line here-- 00:58:06.070 --> 00:58:09.610 the long version of this allele, no difference. 00:58:09.610 --> 00:58:14.910 It's as if if you happen to be born in the biological lottery 00:58:14.910 --> 00:58:18.920 that we all participate in at birth with these version of 00:58:18.920 --> 00:58:21.140 these genes-- and maybe many other genes that are part of 00:58:21.140 --> 00:58:23.890 this story, but they just measured this one. 00:58:23.890 --> 00:58:27.610 That it doesn't matter whether you live in a nice supportive 00:58:27.610 --> 00:58:30.970 environment or a brutalizing, horrible one, your probability 00:58:30.970 --> 00:58:32.800 of depression is about the same. 00:58:32.800 --> 00:58:36.560 It's a protective gene for stresses of life that are 00:58:36.560 --> 00:58:37.900 visited upon you. 00:58:37.900 --> 00:58:42.070 If you have the opposite, the short version, look. 00:58:42.070 --> 00:58:44.840 The worse the environment, you double your chances of 00:58:44.840 --> 00:58:46.230 depression. 00:58:46.230 --> 00:58:50.660 It's as if you're born with a gene that, if you're given a 00:58:50.660 --> 00:58:51.910 terrible environment-- 00:58:51.910 --> 00:58:54.200 this is exactly the interaction, right-- 00:58:54.200 --> 00:58:57.090 then you're very susceptible to that. 00:58:57.090 --> 00:59:01.540 And you see the same rough pattern in all of them, that 00:59:01.540 --> 00:59:05.310 individuals who have this version of the gene seem to be 00:59:05.310 --> 00:59:09.520 relatively impervious to environmental stressors. 00:59:09.520 --> 00:59:11.800 The ones born with this version of the gene are 00:59:11.800 --> 00:59:14.310 terribly-- so if this person's born with this version of the 00:59:14.310 --> 00:59:15.880 gene, but happens to be in a nice supportive 00:59:15.880 --> 00:59:17.550 household, no problem. 00:59:17.550 --> 00:59:19.010 Right? 00:59:19.010 --> 00:59:21.870 But if they happen to be born into a household where they 00:59:21.870 --> 00:59:26.200 experience, sadly, severe maltreatment, big problem. 00:59:26.200 --> 00:59:28.300 And so this is exactly what we imagine if we understood in 00:59:28.300 --> 00:59:32.100 any depth what people are about, the genetic 00:59:32.100 --> 00:59:34.600 potentiations you're born with, what's easy for you or 00:59:34.600 --> 00:59:36.640 hard for you by genes. 00:59:36.640 --> 00:59:39.380 And the world your handed as an infant, not under your 00:59:39.380 --> 00:59:41.600 control, but the environment you're given, supportive or 00:59:41.600 --> 00:59:45.480 threatening, how those two things play out in a sort of 00:59:45.480 --> 00:59:50.640 duet, making you safe or putting you at risk. 00:59:50.640 --> 00:59:52.320 That's exactly what would-- then we would deeply 00:59:52.320 --> 00:59:57.190 understand the biology and the psychology of human life. 00:59:57.190 --> 00:59:58.840 So this is the kind of study that gets a lot of attention, 00:59:58.840 --> 01:00:01.705 because if we had it exactly right, which we don't yet, we 01:00:01.705 --> 01:00:03.890 would understand something really deep about people and 01:00:03.890 --> 01:00:05.140 vulnerability in environments.