WEBVTT 00:00:01.006 --> 00:00:06.156 We have historical records that allow us to know how the ancient Greeks dressed, 00:00:06.180 --> 00:00:07.434 how they lived, 00:00:07.458 --> 00:00:08.980 how they fought ... 00:00:09.004 --> 00:00:10.528 but how did they think? NOTE Paragraph 00:00:11.432 --> 00:00:15.872 One natural idea is that the deepest aspects of human thought -- 00:00:15.896 --> 00:00:17.768 our ability to imagine, 00:00:17.792 --> 00:00:19.189 to be conscious, 00:00:19.213 --> 00:00:20.444 to dream -- 00:00:20.468 --> 00:00:22.087 have always been the same. 00:00:22.872 --> 00:00:24.371 Another possibility 00:00:24.395 --> 00:00:28.118 is that the social transformations that have shaped our culture 00:00:28.142 --> 00:00:31.927 may have also changed the structural columns of human thought. NOTE Paragraph 00:00:32.911 --> 00:00:35.435 We may all have different opinions about this. 00:00:35.459 --> 00:00:38.176 Actually, it's a long-standing philosophical debate. 00:00:38.644 --> 00:00:41.371 But is this question even amenable to science? NOTE Paragraph 00:00:42.834 --> 00:00:45.340 Here I'd like to propose 00:00:45.364 --> 00:00:50.136 that in the same way we can reconstruct how the ancient Greek cities looked 00:00:50.160 --> 00:00:52.548 just based on a few bricks, 00:00:52.572 --> 00:00:56.698 that the writings of a culture are the archaeological records, 00:00:56.722 --> 00:00:58.865 the fossils, of human thought. NOTE Paragraph 00:00:59.905 --> 00:01:01.079 And in fact, 00:01:01.103 --> 00:01:03.309 doing some form of psychological analysis 00:01:03.333 --> 00:01:06.877 of some of the most ancient books of human culture, 00:01:06.901 --> 00:01:12.856 Julian Jaynes came up in the '70s with a very wild and radical hypothesis: 00:01:12.880 --> 00:01:15.293 that only 3,000 years ago, 00:01:15.317 --> 00:01:20.205 humans were what today we would call schizophrenics. 00:01:21.753 --> 00:01:23.261 And he made this claim 00:01:23.285 --> 00:01:26.586 based on the fact that the first humans described in these books 00:01:26.610 --> 00:01:28.514 behaved consistently, 00:01:28.538 --> 00:01:31.554 in different traditions and in different places of the world, 00:01:31.578 --> 00:01:35.110 as if they were hearing and obeying voices 00:01:35.134 --> 00:01:38.174 that they perceived as coming from the Gods, 00:01:38.198 --> 00:01:39.396 or from the muses ... 00:01:40.063 --> 00:01:42.832 what today we would call hallucinations. 00:01:43.888 --> 00:01:46.514 And only then, as time went on, 00:01:46.538 --> 00:01:50.189 they began to recognize that they were the creators, 00:01:50.213 --> 00:01:52.728 the owners of these inner voices. 00:01:53.316 --> 00:01:56.031 And with this, they gained introspection: 00:01:56.055 --> 00:01:58.538 the ability to think about their own thoughts. NOTE Paragraph 00:01:59.785 --> 00:02:03.182 So Jaynes's theory is that consciousness, 00:02:03.206 --> 00:02:06.372 at least in the way we perceive it today, 00:02:06.396 --> 00:02:09.936 where we feel that we are the pilots of our own existence -- 00:02:09.960 --> 00:02:12.697 is a quite recent cultural development. 00:02:13.456 --> 00:02:15.242 And this theory is quite spectacular, 00:02:15.266 --> 00:02:16.699 but it has an obvious problem 00:02:16.723 --> 00:02:20.715 which is that it's built on just a few and very specific examples. 00:02:21.085 --> 00:02:22.848 So the question is whether the theory 00:02:22.872 --> 00:02:27.623 that introspection built up in human history only about 3,000 years ago 00:02:27.647 --> 00:02:30.631 can be examined in a quantitative and objective manner. NOTE Paragraph 00:02:31.543 --> 00:02:35.106 And the problem of how to go about this is quite obvious. 00:02:35.130 --> 00:02:38.590 It's not like Plato woke up one day and then he wrote, 00:02:38.614 --> 00:02:40.273 "Hello, I'm Plato, 00:02:40.297 --> 00:02:43.186 and as of today, I have a fully introspective consciousness." NOTE Paragraph 00:02:43.210 --> 00:02:45.503 (Laughter) NOTE Paragraph 00:02:45.527 --> 00:02:48.860 And this tells us actually what is the essence of the problem. 00:02:49.467 --> 00:02:53.522 We need to find the emergence of a concept that's never said. 00:02:54.434 --> 00:02:58.744 The word introspection does not appear a single time 00:02:58.768 --> 00:03:00.687 in the books we want to analyze. NOTE Paragraph 00:03:01.728 --> 00:03:05.815 So our way to solve this is to build the space of words. 00:03:06.571 --> 00:03:09.858 This is a huge space that contains all words 00:03:09.882 --> 00:03:12.684 in such a way that the distance between any two of them 00:03:12.708 --> 00:03:15.591 is indicative of how closely related they are. 00:03:16.460 --> 00:03:17.611 So for instance, 00:03:17.635 --> 00:03:20.532 you want the words "dog" and "cat" to be very close together, 00:03:20.556 --> 00:03:24.387 but the words "grapefruit" and "logarithm" to be very far away. 00:03:24.809 --> 00:03:28.705 And this has to be true for any two words within the space. NOTE Paragraph 00:03:29.626 --> 00:03:32.967 And there are different ways that we can construct the space of words. 00:03:32.991 --> 00:03:34.634 One is just asking the experts, 00:03:34.658 --> 00:03:36.554 a bit like we do with dictionaries. 00:03:36.896 --> 00:03:38.324 Another possibility 00:03:38.348 --> 00:03:42.063 is following the simple assumption that when two words are related, 00:03:42.087 --> 00:03:44.436 they tend to appear in the same sentences, 00:03:44.460 --> 00:03:45.913 in the same paragraphs, 00:03:45.937 --> 00:03:47.707 in the same documents, 00:03:47.731 --> 00:03:50.913 more often than would be expected just by pure chance. 00:03:52.231 --> 00:03:54.281 And this simple hypothesis, 00:03:54.305 --> 00:03:55.611 this simple method, 00:03:55.635 --> 00:03:57.242 with some computational tricks 00:03:57.266 --> 00:03:58.655 that have to do with the fact 00:03:58.679 --> 00:04:01.743 that this is a very complex and high-dimensional space, 00:04:01.767 --> 00:04:03.432 turns out to be quite effective. NOTE Paragraph 00:04:04.155 --> 00:04:06.957 And just to give you a flavor of how well this works, 00:04:06.981 --> 00:04:10.893 this is the result we get when we analyze this for some familiar words. 00:04:11.607 --> 00:04:12.792 And you can see first 00:04:12.816 --> 00:04:16.094 that words automatically organize into semantic neighborhoods. 00:04:16.118 --> 00:04:18.335 So you get the fruits, the body parts, 00:04:18.359 --> 00:04:20.784 the computer parts, the scientific terms and so on. NOTE Paragraph 00:04:21.119 --> 00:04:25.341 The algorithm also identifies that we organize concepts in a hierarchy. 00:04:25.852 --> 00:04:27.003 So for instance, 00:04:27.027 --> 00:04:30.624 you can see that the scientific terms break down into two subcategories 00:04:30.648 --> 00:04:32.748 of the astronomic and the physics terms. 00:04:33.338 --> 00:04:35.584 And then there are very fine things. 00:04:35.608 --> 00:04:37.513 For instance, the word astronomy, 00:04:37.537 --> 00:04:39.352 which seems a bit bizarre where it is, 00:04:39.376 --> 00:04:41.424 is actually exactly where it should be, 00:04:41.448 --> 00:04:43.043 between what it is, 00:04:43.067 --> 00:04:44.337 an actual science, 00:04:44.361 --> 00:04:45.897 and between what it describes, 00:04:45.921 --> 00:04:47.413 the astronomical terms. NOTE Paragraph 00:04:48.182 --> 00:04:50.073 And we could go on and on with this. 00:04:50.097 --> 00:04:52.157 Actually, if you stare at this for a while, 00:04:52.181 --> 00:04:54.039 and you just build random trajectories, 00:04:54.063 --> 00:04:57.229 you will see that it actually feels a bit like doing poetry. 00:04:58.018 --> 00:04:59.900 And this is because, in a way, 00:04:59.924 --> 00:05:02.864 walking in this space is like walking in the mind. NOTE Paragraph 00:05:04.027 --> 00:05:05.644 And the last thing 00:05:05.668 --> 00:05:09.708 is that this algorithm also identifies what are our intuitions, 00:05:09.732 --> 00:05:13.628 of which words should lead in the neighborhood of introspection. 00:05:13.652 --> 00:05:14.875 So for instance, 00:05:14.899 --> 00:05:18.878 words such as "self," "guilt," "reason," "emotion," 00:05:18.902 --> 00:05:20.791 are very close to "introspection," 00:05:20.815 --> 00:05:21.966 but other words, 00:05:21.990 --> 00:05:24.157 such as "red," "football," "candle," "banana," 00:05:24.181 --> 00:05:25.633 are just very far away. NOTE Paragraph 00:05:26.054 --> 00:05:28.816 And so once we've built the space, 00:05:28.840 --> 00:05:31.666 the question of the history of introspection, 00:05:31.690 --> 00:05:34.023 or of the history of any concept 00:05:34.047 --> 00:05:38.826 which before could seem abstract and somehow vague, 00:05:38.850 --> 00:05:40.454 becomes concrete -- 00:05:40.478 --> 00:05:43.216 becomes amenable to quantitative science. NOTE Paragraph 00:05:44.216 --> 00:05:46.978 All that we have to do is take the books, 00:05:47.002 --> 00:05:48.383 we digitize them, 00:05:48.407 --> 00:05:51.216 and we take this stream of words as a trajectory 00:05:51.240 --> 00:05:53.209 and project them into the space, 00:05:53.233 --> 00:05:56.987 and then we ask whether this trajectory spends significant time 00:05:57.011 --> 00:06:00.003 circling closely to the concept of introspection. NOTE Paragraph 00:06:00.760 --> 00:06:01.956 And with this, 00:06:01.980 --> 00:06:04.092 we could analyze the history of introspection 00:06:04.116 --> 00:06:06.037 in the ancient Greek tradition, 00:06:06.061 --> 00:06:08.663 for which we have the best available written record. 00:06:09.631 --> 00:06:11.886 So what we did is we took all the books -- 00:06:11.910 --> 00:06:14.194 we just ordered them by time -- 00:06:14.218 --> 00:06:15.970 for each book we take the words 00:06:15.994 --> 00:06:17.955 and we project them to the space, 00:06:17.979 --> 00:06:21.011 and then we ask for each word how close it is to introspection, 00:06:21.035 --> 00:06:22.265 and we just average that. 00:06:22.590 --> 00:06:25.788 And then we ask whether, as time goes on and on, 00:06:25.812 --> 00:06:29.064 these books get closer, and closer and closer 00:06:29.088 --> 00:06:30.842 to the concept of introspection. NOTE Paragraph 00:06:30.866 --> 00:06:34.667 And this is exactly what happens in the ancient Greek tradition. 00:06:35.698 --> 00:06:38.825 So you can see that for the oldest books in the Homeric tradition, 00:06:38.849 --> 00:06:42.261 there is a small increase with books getting closer to introspection. 00:06:42.285 --> 00:06:44.491 But about four centuries before Christ, 00:06:44.515 --> 00:06:49.223 this starts ramping up very rapidly to an almost five-fold increase 00:06:49.247 --> 00:06:51.747 of books getting closer, and closer and closer 00:06:51.771 --> 00:06:53.453 to the concept of introspection. 00:06:54.159 --> 00:06:56.583 And one of the nice things about this 00:06:56.607 --> 00:06:57.805 is that now we can ask 00:06:57.829 --> 00:07:01.976 whether this is also true in a different, independent tradition. NOTE Paragraph 00:07:02.962 --> 00:07:06.138 So we just ran this same analysis on the Judeo-Christian tradition, 00:07:06.162 --> 00:07:08.883 and we got virtually the same pattern. 00:07:09.548 --> 00:07:14.183 Again, you see a small increase for the oldest books in the Old Testament, 00:07:14.207 --> 00:07:16.121 and then it increases much more rapidly 00:07:16.145 --> 00:07:17.984 in the new books of the New Testament. 00:07:18.008 --> 00:07:20.040 And then we get the peak of introspection 00:07:20.064 --> 00:07:22.191 in "The Confessions of Saint Augustine," 00:07:22.215 --> 00:07:24.072 about four centuries after Christ. 00:07:24.897 --> 00:07:26.841 And this was very important, 00:07:26.865 --> 00:07:30.238 because Saint Augustine had been recognized by scholars, 00:07:30.262 --> 00:07:32.434 philologists, historians, 00:07:32.458 --> 00:07:34.536 as one of the founders of introspection. 00:07:35.060 --> 00:07:38.357 Actually, some believe him to be the father of modern psychology. NOTE Paragraph 00:07:39.012 --> 00:07:40.851 So our algorithm, 00:07:40.875 --> 00:07:43.717 which has the virtue of being quantitative, 00:07:43.741 --> 00:07:45.004 of being objective, 00:07:45.028 --> 00:07:47.044 and of course of being extremely fast -- 00:07:47.068 --> 00:07:49.465 it just runs in a fraction of a second -- 00:07:49.489 --> 00:07:52.992 can capture some of the most important conclusions 00:07:53.016 --> 00:07:55.238 of this long tradition of investigation. 00:07:56.317 --> 00:07:59.968 And this is in a way one of the beauties of science, 00:07:59.992 --> 00:08:03.468 which is that now this idea can be translated 00:08:03.492 --> 00:08:06.063 and generalized to a whole lot of different domains. NOTE Paragraph 00:08:06.769 --> 00:08:11.536 So in the same way that we asked about the past of human consciousness, 00:08:11.560 --> 00:08:14.966 maybe the most challenging question we can pose to ourselves 00:08:14.990 --> 00:08:19.127 is whether this can tell us something about the future of our own consciousness. 00:08:19.550 --> 00:08:21.020 To put it more precisely, 00:08:21.044 --> 00:08:23.460 whether the words we say today 00:08:23.484 --> 00:08:28.681 can tell us something of where our minds will be in a few days, 00:08:28.705 --> 00:08:29.856 in a few months 00:08:29.880 --> 00:08:31.062 or a few years from now. NOTE Paragraph 00:08:31.597 --> 00:08:34.617 And in the same way many of us are now wearing sensors 00:08:34.641 --> 00:08:36.427 that detect our heart rate, 00:08:36.451 --> 00:08:37.720 our respiration, 00:08:37.744 --> 00:08:39.411 our genes, 00:08:39.435 --> 00:08:43.086 on the hopes that this may help us prevent diseases, 00:08:43.110 --> 00:08:46.631 we can ask whether monitoring and analyzing the words we speak, 00:08:46.655 --> 00:08:49.338 we tweet, we email, we write, 00:08:49.362 --> 00:08:54.170 can tell us ahead of time whether something may go wrong with our minds. 00:08:55.087 --> 00:08:56.621 And with Guillermo Cecchi, 00:08:56.645 --> 00:08:59.646 who has been my brother in this adventure, 00:08:59.670 --> 00:09:01.225 we took on this task. 00:09:02.228 --> 00:09:07.760 And we did so by analyzing the recorded speech of 34 young people 00:09:07.784 --> 00:09:10.585 who were at a high risk of developing schizophrenia. NOTE Paragraph 00:09:11.434 --> 00:09:14.315 And so what we did is, we measured speech at day one, 00:09:14.339 --> 00:09:17.581 and then we asked whether the properties of the speech could predict, 00:09:17.605 --> 00:09:20.101 within a window of almost three years, 00:09:20.125 --> 00:09:22.160 the future development of psychosis. 00:09:23.427 --> 00:09:25.793 But despite our hopes, 00:09:25.817 --> 00:09:28.934 we got failure after failure. 00:09:29.793 --> 00:09:33.675 There was just not enough information in semantics 00:09:33.699 --> 00:09:36.492 to predict the future organization of the mind. 00:09:36.516 --> 00:09:38.325 It was good enough 00:09:38.349 --> 00:09:42.524 to distinguish between a group of schizophrenics and a control group, 00:09:42.548 --> 00:09:45.260 a bit like we had done for the ancient texts, 00:09:45.284 --> 00:09:48.278 but not to predict the future onset of psychosis. NOTE Paragraph 00:09:49.164 --> 00:09:50.870 But then we realized 00:09:50.894 --> 00:09:54.982 that maybe the most important thing was not so much what they were saying, 00:09:55.006 --> 00:09:56.679 but how they were saying it. 00:09:57.679 --> 00:09:58.899 More specifically, 00:09:58.923 --> 00:10:01.750 it was not in which semantic neighborhoods the words were, 00:10:01.774 --> 00:10:04.374 but how far and fast they jumped 00:10:04.398 --> 00:10:06.699 from one semantic neighborhood to the other one. 00:10:07.247 --> 00:10:08.978 And so we came up with this measure, 00:10:09.002 --> 00:10:11.391 which we termed semantic coherence, 00:10:11.415 --> 00:10:16.219 which essentially measures the persistence of speech within one semantic topic, 00:10:16.243 --> 00:10:17.772 within one semantic category. NOTE Paragraph 00:10:19.294 --> 00:10:23.341 And it turned out to be that for this group of 34 people, 00:10:23.365 --> 00:10:27.024 the algorithm based on semantic coherence could predict, 00:10:27.048 --> 00:10:29.548 with 100 percent accuracy, 00:10:29.572 --> 00:10:32.079 who developed psychosis and who will not. 00:10:32.976 --> 00:10:35.913 And this was something that could not be achieved -- 00:10:35.937 --> 00:10:37.445 not even close -- 00:10:37.469 --> 00:10:40.595 with all the other existing clinical measures. NOTE Paragraph 00:10:42.525 --> 00:10:46.104 And I remember vividly, while I was working on this, 00:10:46.128 --> 00:10:48.445 I was sitting at my computer 00:10:48.469 --> 00:10:51.104 and I saw a bunch of tweets by Polo -- 00:10:51.128 --> 00:10:54.295 Polo had been my first student back in Buenos Aires, 00:10:54.319 --> 00:10:56.389 and at the time he was living in New York. 00:10:56.413 --> 00:10:58.501 And there was something in this tweets -- 00:10:58.525 --> 00:11:02.026 I could not tell exactly what because nothing was said explicitly -- 00:11:02.050 --> 00:11:04.071 but I got this strong hunch, 00:11:04.095 --> 00:11:07.050 this strong intuition, that something was going wrong. 00:11:08.347 --> 00:11:11.070 So I picked up the phone, and I called Polo, 00:11:11.094 --> 00:11:13.013 and in fact he was not feeling well. 00:11:13.362 --> 00:11:15.299 And this simple fact, 00:11:15.323 --> 00:11:17.814 that reading in between the lines, 00:11:17.838 --> 00:11:22.100 I could sense, through words, his feelings, 00:11:22.124 --> 00:11:24.743 was a simple, but very effective way to help. NOTE Paragraph 00:11:25.987 --> 00:11:27.625 What I tell you today 00:11:27.649 --> 00:11:30.157 is that we're getting close to understanding 00:11:30.181 --> 00:11:34.467 how we can convert this intuition that we all have, 00:11:34.491 --> 00:11:35.856 that we all share, 00:11:35.880 --> 00:11:37.077 into an algorithm. 00:11:38.102 --> 00:11:39.563 And in doing so, 00:11:39.587 --> 00:11:44.237 we may be seeing in the future a very different form of mental health, 00:11:44.261 --> 00:11:49.882 based on objective, quantitative and automated analysis 00:11:49.906 --> 00:11:51.615 of the words we write, 00:11:51.639 --> 00:11:53.176 of the words we say. NOTE Paragraph 00:11:53.200 --> 00:11:54.351 Gracias. NOTE Paragraph 00:11:54.375 --> 00:12:01.258 (Applause)