Transcription
What are the data on how females signal, um, let's just say, you know, testosterone, estrogen, and um, other, you know, uh, relevant hormones? And for males as well? What are the what are the external signals or behavior or behavioral signals? Yeah, so there so they that there that's a really important point that you made because they both, you know, those things go together. So, uh, it's been most controversial for females, but you know, in my view, the data is pretty clear and it, you know, aligns I think with our own intuitions, um, just from from daily life, which is well, some things are are apparently not consciously perceptible; it's like hard to report. But um, but through studies where you just ask males for like, okay, is this, you know, how attractive is this woman? Or etc., um, that there are changes in the face, for example. And that's been one argument is that this is going to sound funny, but that the signals that non-human primates are in the rear are because we're walking upright; you can't see that really. So now it's kind of in in the face. And so these changes that um happen that that the ovulatory cycle is reflected in the turgidity, how how tight the skin is in the face, because it gets a little plumper and a little bit redder, and we may not be consciously aware of that, but the that that it's there, right? And it shows up in sort of preference data when when when you ask heterosexual male, you know, do you, you know, how attractive is this woman? Etc. So that that seems to be the case. Um, and also um, behavioral, you know, so so uh, sort of flirtatious behavior um increases around the time of ovulation.
Yeah, yeah, yeah. There's there is a classic study that um that exotic dancers, strippers, um would actually get bigger tips, more tips when they were ovulating than when they're not ovulating. Interesting. Uh, so there maybe and it could be by it could be by virtue of their their behavior, their it could be the way they they dance, proximity to the uh to the what I guess, the observers, clients, whatever you call them. I I I don't recall that being um quantified, but um, but it suggests that there's there's a latent signal there and that uh men are uh unconsciously processing this. They're not saying, oh, her cheeks are particularly exactly uh plump and red right now; they're that um, but that if you measure their ratings or scores of of attractiveness when she's ovulating, it's these features that are that might be drawing out that response.
Correct. We can take this back to the monkey porn studies, which is was our first real foray into trying to quantify the uh the value of various kinds of social information for guiding decisions. And we already came into this uh with a sense that like, yeah, things like status, physical prowess, mating status, um, you know, are you are you um you look like a good mate, mad mate? Are you in in mating condition? You know, you etc. And so when you know you think about that like how do you ask a monkey that question? You could ask them; they're not going to tell you, cuz they they can't talk, but you have to develop a behavioral way to elicit that. And so what we did, I think it was pretty clever, was to riff on the studies that you know I had already done uh looking at varying the expected value of two options. So this was the work I did as a postdoc with Paul Glimcher where we um revealed uh economic signals in the brain in the in the parietal cortex, an area between where visual signals come in and where you make a choice um to to to make a behavioral response. And we varied like in this case, monkeys don't work for money; they they'll work for juice. Okay, spend actually it's really fun; you spend a lot of time figuring out what juice they really love best and to then economically you would vary like the size of the juice reward that each of the two offered or its probability while maintaining size constant; that when you combine those, you multiply those together, you get expected value; that's the first model of economic decision-making that was really ever developed, right? You compute the expected value, different options, you choose the one has is the highest value; it it, you know, doesn't work all the time, but it's sort of a rough proxy. And we showed that yeah, neurons and PR cortex signal that monkeys are good economists; they choose the one that has a higher expected value. Okay, so now take that experiment; I'm going to have monkeys choosing between two options that vary in how much juice they pay out, but I'm also going to pop up a picture when they choose one of them, okay? And they don't know what picture's coming up, but the picture's going to be it could be it could be a nothing burger, just like some gray square; it doesn't mean anything, or it could be the the the perianea of a female; if it were males that we were studying, we did this with males uh sorry, females making choices eventually as well; could be face of a dominant male, face of a subordinate male, face of female, ET equivalent of of the uh swollen taint of a female monkey um for if you reverse the experiment and it's the female monkey who's making a choice about male monkeys, what do they what do they find really attractive in a male monkey? Yeah, so it's the taint of the male monkey, cuz it's providing a signal about how much monkeys looking at taints, how much testosterone is circul, you know, that they've got on board basically, which is a good predictor of their status, um, it's a good predictor of their, you know, fighting ability, all that kind of stuff. And and if you're a female and that's that's a reasonable kind of choice to make because if you have male offspring and females are predisposed to choose that, then they'll your male offspring are going to do pretty well. So that's what we did, and we varied how much juice; so sometimes monkeys would get paid; they'd have to give up juice to see the pictures; sometimes they get paid more to see the pictures. And what we did then is we we we construct a choice curve, and we use the differential; if that if it's not 50/50, if it slides one way or the other, it tells us that monkeys are are paying x amount to to see certain kinds of pictures or you have to overpay them, right? And so what did we find? It was really I think scientifically revealing, but it's pretty fun; people got it immediately; uh, they will pay juice, juice; they will give up juice; they will pay it to see pictures of the perianea, the the hind quarters of females; this was original study was in male monkeys; they will pay to see the faces of dominant males, and you had to pay them to see the faces of subordinate males.
Okay, so so so females will give up juice to see the taints of testosterone-rich male monkeys, and male monkeys will pay juice to see the swollen taints of female monkeys that are because the swelling indicates a better reproductive competence; yes, better, you know, DS, the time the time is ripe, okay, to to to M, but it just in general it's a signal that is like what we would say is it's important, has value, something you should track. And in fact, yeah, they're paying for it. So you know this just blew up on the Internet, even back then; it was like suddenly M, every website was like, oh, you proven monkey porn, blah blah blah. Um, it was kind of a fun ride; it did it was a New York Times uh idea of the year uh in 2005, which was um again kind of shocking, you know, this like word on that, but but people it makes sense. And the thing I want to point out is that um we ran the same experiment in people, not with uh unclothed humans, so we used and we used only well, no, it was it was and we had to create our own stimulus set because all the stimulus sets that were out there for visual studies of humans were like a bunch of, you know, German people looking very D; they were very well controlled, and we wanted something that's more natural. So we downloaded thousands of photos from this website, hotter.com; I don't know if you recall that, but it was a website where you could upload pictures and people would rate you; I mean, now that like probably wouldn't be allowed now. I remember I remember Rate My Pet, Rate My Pet, Rate My Professor, I think, which is still around. When you're saying rate rate, yes, rate rate with a T, my pet. Yeah, but this was hotter.com. So you get all these really natural-looking. And then we had this was really funny though, too. Um, so we had uh a group of separate groups of raters uh from the people who we actually test in the experiment. So we had, you know, a group of males, heterosexual males rating the female photos and vice versa. And um, that was interesting in its own right. So we were just trying to establish like we're not saying why they're attractive or anything like that, just like let's measure it, okay? And it was really fun because um, you know, by the and it took was hard work; you're having to do one every three seconds, and it took like an hour, and the uh, you know, when the women were done rating, they're like, okay, I'm glad that's over; uh, the hour is over. And our male raters were like, do you have any more? Um, you know, can I I I'd be happy to sit here and rate more photographs for you.
Interesting. Um, so women got sort of like uh they got tired of rating males for attractiveness; yes, males did not tire of rating females for; they did not at all, which that's anecdotal, but it's still I think it's revealing. Then we ran the pay-per-view experiment just like in monkeys uh on humans, and we also uh ran a couple of other economically, you know, econ standard economic tasks; one would be how long are you willing to wait? So that's a delay discounting, like, and generally you you will wait longer for a bigger reward, a smaller reward, and also how hard would you work? And we the work was like you had to alternate pressing two keys on a keyboard; it was really just menial, laborious, you know, etc. So um, the two interesting, just sociologically, it's interesting what comes out of this; um, our female subjects um basically wouldn't give up money; they were working for money; they were hearing the sound of coins coming out of a slot machine, which is proportional to how much money they actually got; choice, real money; if you ignored the pictures, you'd go home with like $17 uh extra compared to if if you were influenced by them. And the females did really well economically; so they pretty much kind of ignored the pictures of the males, even though they were rated, even the ones that were super hot; they were not very very uh concerned with that. For the males, it was the exact opposite. So the males are giving up essentially; they're paying, and they they had thousands of trials; they're paying somewhere between a half and three-quarters of a cent to see images of women who are rated in the top like third of of attractiveness; they also would wait significantly longer, and they would work really hard; it's like rats pressing for cocaine, quite literally, to keep those pictures up on the screen. Okay, so that's the setting we've established in monkeys and in people; similar economic principles uh that are guiding social you call attention, social evaluation, whatever. So we're like, okay, let's go look in the brain. So we did an MRI experiment, fMRI experiment, to measure measured blood flow to you know, different parts of the brain um in we only tested males um because they were the ones who displayed uh, you know, differential preferences there. And what we found is that um kind of parts of the visual system that are involved in encoding faces, but then the reward system was activated and tracked linearly how much money these guys were paying to see uh images; there's basically the trade-off value, the currency, the translation of pictures into money. Okay, then in monkeys, we studied all the same areas, but now we could record from individual neurons in those areas rather than looking at blood flow, which is a crude proxy. And we found exactly the same thing, which is that you know neurons in a reward system uh were spontaneously and strongly activated by those um pictures, you know, that uh and that made sense, right? So the pictures of the perianea of females um by uh dominant male faces um and that correspondence I thought was pretty compelling.