0:00:00.567,0:00:05.098 In the 17th century, a woman named Giulia Tofana 0:00:05.098,0:00:07.809 had a very successful perfume business. 0:00:07.809,0:00:10.066 For over 50 years she ran it. 0:00:10.066,0:00:12.851 It sort of ended abruptly when she was executed — (Laughter) — 0:00:12.851,0:00:18.282 for murdering 600 men. You see, it wasn't a very good perfume. 0:00:18.282,0:00:22.148 In fact, it was completely odorless and tasteless and colorless, 0:00:22.148,0:00:25.472 but as a poison, it was the best money could buy, 0:00:25.472,0:00:29.265 so women flocked to her in order to murder their husbands. 0:00:29.265,0:00:34.525 It turns out that poisoners were a valued and feared group, 0:00:34.525,0:00:38.694 because poisoning a human being is a quite difficult thing. 0:00:38.694,0:00:42.029 The reason is, we have sort of a built-in poison detector. 0:00:42.029,0:00:45.293 You can see this as early as even in newborn infants. 0:00:45.293,0:00:47.864 If you are willing to do this, you can take a couple of drops 0:00:47.864,0:00:50.427 of a bitter substance or a sour substance, 0:00:50.427,0:00:54.199 and you'll see that face, the tongue stick out, the wrinkled nose, 0:00:54.199,0:00:57.071 as if they're trying to get rid of what's in their mouth. 0:00:57.071,0:01:00.023 This reaction expands into adulthood and becomes 0:01:00.023,0:01:03.543 sort of a full-blown disgust response, no longer just 0:01:03.543,0:01:05.995 about whether or not we're about to be poisoned, 0:01:05.995,0:01:08.952 but whenever there's a threat of physical contamination 0:01:08.952,0:01:13.083 from some source. But the face remains strikingly similar. 0:01:13.083,0:01:17.036 It has expanded more, though, than just keeping us away 0:01:17.036,0:01:19.217 from physical contaminants, and there's a growing 0:01:19.217,0:01:22.700 body of evidence to suggest that, in fact, this emotion 0:01:22.700,0:01:25.742 of disgust now influences our moral beliefs 0:01:25.742,0:01:29.638 and even our deeply held political intuitions. 0:01:29.638,0:01:33.274 Why this might be the case? 0:01:33.274,0:01:36.269 We can understand this process by understanding 0:01:36.269,0:01:39.419 a little bit about emotions in general. So the basic human emotions, 0:01:39.419,0:01:42.614 those kinds of emotions that we share with all other human beings, 0:01:42.614,0:01:45.415 exist because they motivate us to do good things 0:01:45.415,0:01:47.726 and they keep us away from doing bad things. 0:01:47.726,0:01:51.109 So by and large, they are good for our survival. 0:01:51.109,0:01:53.918 Take the emotion of fear, for instance. It keeps us away 0:01:53.918,0:01:56.422 from doing things that are really, really risky. 0:01:56.422,0:02:00.262 This photo taken just before his death — (Laughter) — 0:02:00.262,0:02:03.108 is actually a — No, one reason this photo is interesting 0:02:03.108,0:02:06.725 is because most people would not do this, and if they did, 0:02:06.725,0:02:08.725 they would not live to tell it, because fear would have 0:02:08.725,0:02:12.400 kicked in a long time ago to a natural predator. 0:02:12.400,0:02:16.007 Just like fear offers us protective benefits, disgust seems 0:02:16.007,0:02:18.341 to do the same thing, except for what disgust does is 0:02:18.341,0:02:20.936 keeps us away from not things that might eat us, 0:02:20.936,0:02:23.601 or heights, but rather things that might poison us, 0:02:23.601,0:02:26.198 or give us disease and make us sick. 0:02:26.198,0:02:29.455 So one of the features of disgust that makes it such 0:02:29.455,0:02:34.238 an interesting emotion is that it's very, very easy to elicit, 0:02:34.238,0:02:37.121 in fact more so than probably any of the other basic emotions, 0:02:37.121,0:02:39.490 and so I'm going to show you that with a couple of images 0:02:39.490,0:02:41.373 I can probably make you feel disgust. 0:02:41.373,0:02:44.568 So turn away. I'll tell you when you can turn back. 0:02:44.568,0:02:45.701 (Laughter) 0:02:45.701,0:02:50.034 I mean, you see it every day, right? I mean, come on. (Laughter) 0:02:50.034,0:02:51.247 (Audience: Ewww.) 0:02:51.247,0:02:54.256 Okay, turn back, if you didn't look. 0:02:54.256,0:02:56.791 Those probably made a lot of you in the audience 0:02:56.791,0:03:00.626 feel very, very disgusted, but if you didn't look, 0:03:00.626,0:03:03.156 I can tell you about some of the other things that have been shown 0:03:03.156,0:03:05.839 sort of across the world to make people disgusted, 0:03:05.839,0:03:09.443 things like feces, urine, blood, rotten flesh. 0:03:09.443,0:03:11.277 These are the sorts of things that it makes sense 0:03:11.277,0:03:14.531 for us to stay away from, because they might actually contaminate us. 0:03:14.531,0:03:16.826 In fact, just having a diseased appearance 0:03:16.826,0:03:19.226 or odd sexual acts, these things are also 0:03:19.226,0:03:22.217 things that give us a lot of disgust. 0:03:22.217,0:03:24.595 Darwin was probably one of the first scientists 0:03:24.595,0:03:26.538 to systematically investigate the human emotions, 0:03:26.538,0:03:30.227 and he pointed to the universal nature and the strength 0:03:30.227,0:03:32.076 of the disgust response. 0:03:32.076,0:03:35.347 This is an anecdote from his travels in South America. 0:03:35.347,0:03:37.083 "In Tierro del Fuego a native touched with his finger 0:03:37.083,0:03:39.588 some cold preserved meat while I was eating ... 0:03:39.588,0:03:43.107 and plainly showed disgust at its softness, whilst I felt 0:03:43.107,0:03:46.105 utter disgust at my food being touched by a naked savage — (Laughter) — 0:03:46.105,0:03:48.262 though his hands did not appear dirty." 0:03:48.262,0:03:53.660 He later wrote, "It's okay, some of my best friends are naked savages." (Laughter) 0:03:53.660,0:03:56.404 Well it turns out it's not only old-timey British scientists 0:03:56.404,0:03:58.685 who are this squeamish. I recently got a chance 0:03:58.685,0:04:00.975 to talk to Richard Dawkins for a documentary, 0:04:00.975,0:04:04.842 and I was able to disgust him a bunch of times. Here's my favorite. 0:04:04.842,0:04:07.207 Richard Dawkins: "We've evolved around courtship and sex, 0:04:07.207,0:04:10.229 are attached to deep-rooted emotions and reactions 0:04:10.229,0:04:14.929 that are hard to jettison overnight." 0:04:14.929,0:04:18.966 David Pizarro: So my favorite part of this clip is that 0:04:18.966,0:04:21.609 Professor Dawkins actually gagged. 0:04:21.609,0:04:25.194 He jumps back, and he gags, and we had to do it three times, 0:04:25.194,0:04:28.750 and all three times he gagged. (Laughter) 0:04:28.750,0:04:31.896 And he was really gagging. I thought he might throw up on me, actually. 0:04:31.896,0:04:35.112 One of the features, though, of disgust, 0:04:35.112,0:04:38.042 is not just its universality and its strength, 0:04:38.042,0:04:41.081 but the way that it works through association. 0:04:41.081,0:04:44.816 So when one disgusting thing touches a clean thing, 0:04:44.816,0:04:48.170 that clean thing becomes disgusting, not the other way around. 0:04:48.170,0:04:51.377 This makes it very useful as a strategy if you want to 0:04:51.377,0:04:53.143 convince somebody that an object or an individual 0:04:53.143,0:04:56.811 or an entire social group is disgusting and should be avoided. 0:04:56.811,0:04:59.352 The philosopher Martha Nussbaum points this out 0:04:59.352,0:05:01.436 in this quote: "Thus throughout history, certain disgust 0:05:01.436,0:05:04.677 properties -- sliminess, bad smell, stickiness, decay, foulness -- 0:05:04.677,0:05:06.977 have been repeatedly and monotonously been associated with ... 0:05:06.977,0:05:10.829 Jews, women, homosexuals, untouchables, lower-class people -- 0:05:10.829,0:05:14.343 all of those are imagined as tainted by the dirt of the body." 0:05:14.343,0:05:17.475 Let me give you just some examples of how, some powerful 0:05:17.475,0:05:19.847 examples of how this has been used historically. 0:05:19.847,0:05:23.437 This comes from a Nazi children's book published in 1938: 0:05:23.437,0:05:26.247 "Just look at these guys! The louse-infested beards, 0:05:26.247,0:05:29.557 the filthy, protruding ears, those stained, fatty clothes... 0:05:29.557,0:05:32.323 Jews often have an unpleasant sweetish odor. 0:05:32.323,0:05:35.116 If you have a good nose, you can smell the Jews." 0:05:35.116,0:05:37.649 A more modern example comes from people who try to 0:05:37.649,0:05:40.110 convince us that homosexuality is immoral. 0:05:40.110,0:05:43.795 This is from an anti-gay website, where they said 0:05:43.795,0:05:47.072 gays are "worthy of death for their vile ... sex practices." 0:05:47.072,0:05:50.738 They're like "dogs eating their own vomit and sows wallowing in their own feces." 0:05:50.738,0:05:53.482 These are disgust properties that are trying to be directly 0:05:53.482,0:05:56.831 linked to the social group that you should not like. 0:05:56.831,0:05:59.603 When we were first investigating the role of disgust in 0:05:59.603,0:06:03.472 moral judgment, one of the things we became interested in 0:06:03.472,0:06:07.775 was whether or not these sorts of appeals are more likely 0:06:07.775,0:06:10.840 to work in individuals who are more easily disgusted. 0:06:10.840,0:06:12.969 So while disgust, along with the other basic emotions, 0:06:12.969,0:06:15.585 are universal phenomena, it just really is true 0:06:15.585,0:06:17.883 that some people are easier to disgust than others. 0:06:17.883,0:06:19.569 You could probably see it in the audience members 0:06:19.569,0:06:21.626 when I showed you those disgusting images. 0:06:21.626,0:06:24.326 The way that we measured this was by a scale that was 0:06:24.326,0:06:26.655 constructed by some other psychologists 0:06:26.655,0:06:29.512 that simply asked people across a wide variety of situations 0:06:29.512,0:06:31.613 how likely they are to feel disgust. 0:06:31.613,0:06:33.406 So here are a couple of examples. 0:06:33.406,0:06:35.578 "Even if I were hungry, I would not drink a bowl of my 0:06:35.578,0:06:39.386 favorite soup if it had been stirred by a used but thoroughly washed fly-swatter." 0:06:39.386,0:06:40.951 "Do you agree or disagree?" (Laughter) 0:06:40.951,0:06:43.231 "While you are walking through a tunnel under a railroad track, 0:06:43.231,0:06:46.895 you smell urine. Would you be very disgusted or not at all disgusted?" 0:06:46.895,0:06:49.551 If you ask enough of these, you can get a general overall 0:06:49.551,0:06:51.914 score of disgust sensitivity. 0:06:51.914,0:06:54.387 It turns out that this score is actually meaningful. 0:06:54.387,0:06:57.464 When you bring people into the laboratory and you ask 0:06:57.464,0:07:01.293 them if they're willing to engage in safe but disgusting behaviors 0:07:01.293,0:07:06.315 like eating chocolate that's been baked to look like dog poop, 0:07:06.315,0:07:10.280 or in this case eating some mealworms that are perfectly healthy but pretty gross, 0:07:10.280,0:07:13.271 your score on that scale actually predicts whether or not 0:07:13.271,0:07:15.614 you'll be willing to engage in those behaviors. 0:07:15.614,0:07:18.212 The first time that we set out to collect data on this 0:07:18.212,0:07:20.222 and associate it with political or moral beliefs, 0:07:20.222,0:07:23.099 we found a general pattern -- 0:07:23.099,0:07:26.401 this is with the psychologists Yoel Inbar and Paul Bloom -- 0:07:26.401,0:07:30.421 that in fact, across three studies we kept finding 0:07:30.421,0:07:32.942 that people who reported that they were easily disgusted 0:07:32.942,0:07:36.397 also reported that they were more politically conservative. 0:07:36.397,0:07:38.281 Another way to say this, though, is that people 0:07:38.281,0:07:43.688 who are very liberal are very hard to disgust. (Laughter) 0:07:43.688,0:07:47.958 In a more recent follow-up study, we were able to look at 0:07:47.958,0:07:50.639 a much greater sample, a much larger sample. In this case, 0:07:50.639,0:07:53.231 this is nearly 30,000 U.S. respondents, 0:07:53.231,0:07:56.008 and we find the same pattern. As you can see, 0:07:56.008,0:07:57.953 people who are on the very conservative side 0:07:57.953,0:08:00.655 of answering the political orientation scale are 0:08:00.655,0:08:03.425 also much more likely to report that they're easily disgusted. 0:08:03.425,0:08:05.920 This data set also allowed us to statistically control 0:08:05.920,0:08:08.144 for a number of things that we knew were both related 0:08:08.144,0:08:11.059 to political orientation and to disgust sensitivity. 0:08:11.059,0:08:13.664 So we were able to control for gender, age, income, 0:08:13.664,0:08:16.955 education, even basic personality variables, 0:08:16.955,0:08:19.257 and the result stays the same. 0:08:19.257,0:08:22.683 When we actually looked at not just self-reported political orientation, 0:08:22.683,0:08:25.583 but voting behavior, we were able to look geographically 0:08:25.583,0:08:28.529 across the nation. What we found was that in regions 0:08:28.529,0:08:32.426 in which people reported high levels of disgust sensitivity, 0:08:32.426,0:08:34.413 McCain got more votes. 0:08:34.413,0:08:37.531 So it not only predicted self-reported political orientation, 0:08:37.531,0:08:39.903 but actual voting behavior. And also we were able, 0:08:39.903,0:08:42.595 with this sample, to look across the world, 0:08:42.595,0:08:46.189 in 121 different countries we asked the same questions, 0:08:46.189,0:08:50.116 and as you can see, this is 121 countries collapsed 0:08:50.116,0:08:52.486 into 10 different geographical regions. 0:08:52.486,0:08:55.110 No matter where you look, what this is plotting is the size 0:08:55.110,0:08:58.521 of the relationship between disgust sensitivity and political orientation, 0:08:58.521,0:09:02.160 and no matter where we looked, we saw a very similar effect. 0:09:02.160,0:09:05.597 Other labs have actually looked at this as well 0:09:05.597,0:09:07.774 using different measures of disgust sensitivity, 0:09:07.774,0:09:10.326 so rather than asking people how easily disgusted they are, 0:09:10.326,0:09:12.666 they hook people up to physiological measures, 0:09:12.666,0:09:14.294 in this case skin conductance. 0:09:14.294,0:09:16.522 And what they've demonstrated is that people who report 0:09:16.522,0:09:20.648 being more politically conservative are also more physiologically aroused 0:09:20.648,0:09:24.222 when you show them disgusting images like the ones that I showed you. 0:09:24.222,0:09:26.391 Interestingly, what they also showed in a finding 0:09:26.391,0:09:30.416 that we kept getting in our previous studies as well 0:09:30.416,0:09:34.163 was that one of the strongest influences here is that 0:09:34.163,0:09:36.373 individuals who are very disgust-sensitive not only are 0:09:36.373,0:09:38.459 more likely to report being politically conservative, but 0:09:38.459,0:09:41.468 they're also very much more opposed to gay marriage 0:09:41.468,0:09:43.617 and homosexuality and pretty much a lot of 0:09:43.617,0:09:47.382 the socio-moral issues in the sexual domain. 0:09:47.382,0:09:50.871 So physiological arousal predicted, in this study, 0:09:50.871,0:09:52.569 attitudes toward gay marriage. 0:09:52.569,0:09:55.788 But even with all these data linking disgust sensitivity 0:09:55.788,0:09:58.947 and political orientation, one of the questions that remains is 0:09:58.947,0:10:02.018 what is the causal link here? Is it the case that 0:10:02.018,0:10:05.292 disgust really is shaping political and moral beliefs? 0:10:05.292,0:10:07.852 We have to resort to experimental methods to answer this, 0:10:07.852,0:10:10.627 and so what we can do is actually bring people into the lab 0:10:10.627,0:10:13.050 and disgust them and compare them to a control group 0:10:13.050,0:10:15.458 that hasn't been disgusted. It turns out that over 0:10:15.458,0:10:18.186 the past five years a number of researchers have done this, 0:10:18.186,0:10:21.012 and by and large the results have all been the same, 0:10:21.012,0:10:23.441 that when people are feeling disgust, their attitudes 0:10:23.441,0:10:25.544 shift towards the right of the political spectrum, 0:10:25.544,0:10:28.220 toward more moral conservatism as well. 0:10:28.220,0:10:31.900 So this is whether you use a foul odor, a bad taste, 0:10:31.900,0:10:37.190 from film clips, from post-hypnotic suggestions of disgust, 0:10:37.190,0:10:39.556 images like the ones I've shown you, even just 0:10:39.556,0:10:41.519 reminding people that disease is prevalent and they should 0:10:41.519,0:10:45.158 be wary of it and wash up, right, to keep clean, 0:10:45.158,0:10:47.938 these all have similar effects on judgment. 0:10:47.938,0:10:50.304 Let me just give you an example from a recent study 0:10:50.304,0:10:53.264 that we conducted. We asked participants 0:10:53.264,0:10:57.961 to just simply give us their opinion of a variety of social groups, 0:10:57.961,0:11:02.373 and we either made the room smell gross or not. 0:11:02.373,0:11:05.544 When the room smelled gross, what we saw was that 0:11:05.544,0:11:09.215 individuals actually reported more negative attitudes toward gay men. 0:11:09.215,0:11:11.438 Disgust didn't influence attitudes toward all the other 0:11:11.438,0:11:13.831 social groups that we asked, including African-Americans, 0:11:13.831,0:11:17.693 the elderly. It really came down to the attitudes they had 0:11:17.693,0:11:19.086 toward gay men. 0:11:19.086,0:11:22.647 In another set of studies we actually simply reminded people -- 0:11:22.647,0:11:24.573 this was at a time when the swine flu was going around -- 0:11:24.573,0:11:27.057 we reminded people that in order to prevent the spread 0:11:27.057,0:11:30.775 of the flu that they ought to wash their hands. 0:11:30.775,0:11:35.190 For some participants, we actually had them take questionnaires 0:11:35.190,0:11:38.111 next to a sign that reminded them to wash their hands. 0:11:38.111,0:11:40.631 And what we found was that just taking a questionnaire 0:11:40.631,0:11:44.344 next to this hand-sanitizing reminder made individuals 0:11:44.344,0:11:47.507 report being more politically conservative. 0:11:47.507,0:11:49.544 And when we asked them a variety of questions about 0:11:49.544,0:11:52.967 the rightness or wrongness of certain acts, what we also 0:11:52.967,0:11:55.282 found was that simply being reminded that they ought 0:11:55.282,0:11:58.591 to wash their hands made them more morally conservative. 0:11:58.591,0:12:00.888 In particular, when we asked them questions about 0:12:00.888,0:12:04.662 sort of taboo but fairly harmless sexual practices, 0:12:04.662,0:12:07.288 just being reminded that they ought to wash their hands 0:12:07.288,0:12:09.851 made them think that they were more morally wrong. 0:12:09.851,0:12:12.251 Let me give you an example of what I mean by harmless 0:12:12.251,0:12:15.016 but taboo sexual practice. We gave them scenarios. 0:12:15.016,0:12:18.774 One of them said a man is house-sitting for his grandmother. 0:12:18.774,0:12:21.492 When his grandmother's away, he has sex with his girlfriend 0:12:21.492,0:12:22.840 on his grandma's bed. 0:12:22.840,0:12:25.337 In another one, we said a woman enjoys masturbating 0:12:25.337,0:12:29.231 with her favorite teddy bear cuddled next to her. (Laughter) 0:12:29.231,0:12:31.863 People find these to be more morally abhorrent 0:12:31.863,0:12:36.179 if they've been reminded to wash their hands. (Laughter) 0:12:36.179,0:12:39.371 (Laughter) 0:12:39.371,0:12:42.900 Okay. The fact that emotions influence our judgment 0:12:42.900,0:12:44.783 should come as no surprise. I mean, 0:12:44.783,0:12:46.184 that's part of how emotions work. 0:12:46.184,0:12:47.748 They not only motivate you to behave in certain ways, 0:12:47.748,0:12:49.832 but they change the way you think. 0:12:49.832,0:12:52.622 In the case of disgust, what is a little bit more surprising 0:12:52.622,0:12:56.067 is the scope of this influence. It makes perfect sense, 0:12:56.067,0:12:58.946 and it's a very good emotion for us to have, that disgust 0:12:58.946,0:13:01.602 would make me change the way that I perceive 0:13:01.602,0:13:04.645 the physical world whenever contamination is possible. 0:13:04.645,0:13:07.577 It makes less sense that an emotion that was built 0:13:07.577,0:13:10.483 to prevent me from ingesting poison should predict 0:13:10.483,0:13:13.859 who I'm going to vote for in the upcoming presidential election. 0:13:13.859,0:13:16.667 The question of whether disgust ought to influence 0:13:16.667,0:13:19.019 our moral and political judgments 0:13:19.019,0:13:22.155 certainly has to be complex, and might depend on exactly 0:13:22.155,0:13:24.837 what judgments we're talking about, and as a scientist, 0:13:24.837,0:13:26.843 we have to conclude sometimes that the scientific method 0:13:26.843,0:13:30.347 is just ill-equipped to answer these sorts of questions. 0:13:30.347,0:13:32.395 But one thing that I am fairly certain about is, 0:13:32.395,0:13:35.214 at the very least, what we can do with this research is 0:13:35.214,0:13:38.066 point to what questions we ought to ask in the first place. 0:13:38.066,0:13:42.066 Thank you. (Applause)