Leiter on EP

Brian Leiter has finally said something about Evolutionary Psychology that is more than just quick verbal jab. He did so in the update to this post. Note that the update is many times longer than the original post. I like it when people back up their claims with arguments. Maybe Leiter will do it more often, now.

If you're familiar with Gould's critique of EP, then you probably don't need to read Leiter's post (though there are some interesting facts in it), because it's pretty much the same thing. Interestingly, Buller, whom Leiter has mentioned favorably in the past, spends some time in his book arguing that this line of attack (the "we can't just assume it's an adaptation" line) is a critique that is neither fair to EP, nor extremely damaging to it. It will be interesting to see whether Leiter, in the article on biology in law that he says he is writing, references Buller or some of the replies to this critique by Evolutionary Psychologists. For the most part, on the biological side of things, I'd prefer to take Buller's approach, which, by the way, also notes that EP is woefully poor biologically (and neuroscientifically, and methodologically, and cognitively, and so on).

UPDATE: I should have noted that Leiter's arguments are more than those of Gould. Tacked on are those of Elisabeth Lloyd. I mention this mostly to post a link to her very good paper on EP, which you should read.

If You Were Wondering Why I Blog Anonymously

See here.

Another Note on the Study of Bisexuality

People are reacting quite harshly to the study on sexual arousal in bisexual males described in the previous post, especially in the comments here (Lindsay actually takes a level-headed approach to the study, though some of her commenters do not), here, and here. One commenter even went so far as to label the research "Bell Curve-esque," arguing that no matter how good the study is, we should not accept it, writing,

"Reform" in this case is capitulation to an anti-democratic, anti-human agenda, couched in terms of "scientific freedom of inquiry."

This level of hyperbole is just plain absurd, especially coming from people who haven't read the study! Criticize Bailey for being dramatic and going beyond his data, but don't dismiss scientific results just because you don't like them, or argue that studies on the topic of sexual arousal in different groups shouldn't be done. The questions that motivate such research are interesting, and potentially important. It's true that some people, including (perhaps) Bailey will misuse the results, but that's where scientists and supporters of scientists have to step in and say, "No! Look at the data, not the spin." That's what I tried to do in the last post, but for the most part, people commenting on the study have been blinded by the NYT spin (which is, in part, Bailey's spin).

I personally think the study raises all sorts of interesting questions about sexual orientation, the relationship between subjective and physical arousal in different contexts, the connection between sexual attraction and physical arousal, and so on, that are largely unanswered and warrant further research that can shed a great deal of light on human sexuality. It's a damn shame that the New York Times, Bailey (though not entirely -- see again the quote from the discussion section of his paper in the previous post), and the blog commenters are ignoring those questions, that all of them are doing so for ideological reasons, and in the case of the blog commenters and, in all likelihood, the NYT reporter, without having read the fucking research. You simply cannot evaluate a study based on an article about it in the New York Times (a fact, I should note, that Lindsay is well aware of, and is even now looking to the research reports before she comments further on the topic). It is undeniable that ideology can drive scientific work, but it is also undeniable that even ideologically-driven research can raise interesting questions and lead to new, interesting, and important research directions.

Here, by the way, are some quotes from the research article that explicitly avoid some of the ideological-biases that Bailey displays in the NYT quotes:

Sexual orientation refers to the degree of sexual attraction, fantasy, and arousal that one experiences for members of the opposite sex, same sex, or both.

Note that here, unlike in the article, Bailey and his students define sexual orientation with reference to much more than simple physical arousal.

In terms of behvior and identity, bisexual men clearly exist. Skepticism about male bisexuality must therefore concern claims about bisexual feelings, that is, strong sexual attraction and arousal to both sexes. The primary methodological challenge for investigating this issue is to employ a measure of sexual feelings that does not depend on self-report. At present, this is possible only for genital sexual arousal.

In other words, bisexuality does exist, but questions about it remain. This study is an attempt to answer one of those questions, and the authors note that their ability to do so is extremely limited because only genital sexual arousal is easily and reliably measurable. This qualifies any interpretation of the data they gather, and they note this both in the introduction and discussion sections of the paper. Furthermore, the finding of subjective arousal clearly shows the existence of strong sexual attraction to both sexes, even if this attraction does not correlate with genital sexual arousal. Once again, this means that the study raises more questions than it answers, but the questions are interesting, and should be explored.

Does Male Bisexuality Exist?

Does bisexuality exist? No one study could answer such a complex question, since sexuality is not a strictly objective thing. Of course, that didn't keep the New York Times from reporting on one study, and doing so quite poorly. Once again, the mainstream media shows that, if you want scientific knowledge to spread, it is incapable of performing the task. Though in this case, the primary researcher, Michael Bailey of Northwestern University, didn't help much. He said some pretty stupid things, like, "There's no hint that true bisexual arousal exists, and that for men arousal is orientation." As someone who has been in the spotlight before, and at the center of a great deal of controversy due to the fact that he does research on the genetics of sexual orientation, and published a widely-criticized book on transsexuals, Bailey should know better than to give juicy quotes like that to a reporter. It's something he simply can't back up with evidence. As a result of the careless speech and sloppy reporting of Bailey and the New York Times, several bloggers have attacked (and another) the study based on what the article reports. Therefore, I feel the need to describe the study in a bit more detail than the article, and without all of its drama.

Bailey does have evidence about the existence of bisexuality in men. It's very preliminary,and hardly tells a definitive story, but at least it's some evidence. It's a shame that in his interview, he didn't stick to it, and that the reporter wasn't responsible enough to do so either. The evidence is reported in a paper titled "Sexual arousal patterns of bisexual men," by Rieger, Chivers, and Bailey (Rieger and Chivers are two of his graduate students) that is currently in press at Psychological Science. Here are the basics of the experiment. Bailey and his students recruited 30 gay, 38 straight, and 33 bisexual men through "gay-oriented" and alternative magazines in the Chicago area. Sexual orientation was measured entirely through self-report, using the Kinsey scale, with 1 indicating homosexuality, 5 indicating heterosexuality, and 2-4 indicating bisexuality. They had these men view six 2-minute videos of sexual material, along with videos of sexually-neutral material. Two of the sexual videos showed male-male sex (oral and anal), two showed female-female sex (oral and vaginal penetration using a strap-on dildo), and two showed male-female sex (oral and vaginal). They measured physical arousal using a technique called plethysmography that measures changes in the circumference of the penis. This is a fairly widely used technique, and short of neuroimaging (which comes with its own set of problems), it's the best way to measure physical arousal. In addition, they had the participants rate their subjective arousal continuously, using a lever that could be moved in a 180 degree arc, with 0 meaning no arousal, and 180 meaning orgasm-level arousal.

After weeding out several participants due to insufficient levels of arousal to any of the sexual videos (plethysmography is notoriously bad at detecting low levels of arousal), they compared the physical and subjective arousal of the 22 remaining self-reported bisexual to the 21 straight and 25 gay men who made the statistical cut. The question was, do self-reported bisexual men show and report significantly more arousal to male-male sex videos than straight men, and to female-female videos than gay men^*? This is what we would predict if bisexual men are attracted to both sexes. This is in fact what they found for the subjective arousal measure. Bisexual men showed high levels of subjective arousal to both male-male and female-female videos. However, the measures of physical arousal were not consistent with bisexual attraction to both genders. Instead, the bisexual men showed high levels of arousal to either the male-male or female-female videos, but not both. Most of them showed high levels of arousal only to the male-male videos. Bisexual males were the only ones in the study whose subjective and physical arousal levels did not show high positive correlations.

What does this mean? Here is what the authors of the study concluded:

[O]ur results suggest that male bisexuality is not simply the sum of, or the intermediate between, heterosexual and homosexual orientation. Indeed, with respect to sexual arousal and attraction, it remains to be shown that male bisexuality exists. Thus, future research should also explore nonsexual reasons why some men might prefer a bisexual identity to a homosexual or heterosexual identity.

Now this is a carefully worded paragraph at the end of a discussion section in a scientific paper (the emphasis is all mine). Their results don't say anything conclusively, they merely "suggest," and while the authors clearly believe that bisexuality doesn't exist, they only say that its existence "remains to be shown." In addition, they don't suggest that further research on the existence of bisexuality should not be conducted, but that researchers should also study alternative explanations for self-reported bisexuality.

Now there are problems with this conclusion. First, they offer no justification anywhere in the article for equating sexual attraction with sexual arousal as measured by changes in the circumference of the penis. In fact, they do have evidence that bisexual "attraction," if not arousal, exists. The evidence is in their measures of subjective arousal. If subjective arousal doesn't measure attraction, then I have no idea what it measures. What they did find, it appears, is a dissociation between attraction and arousal for bisexual men. What this means, however, is a question that will have to be answered by future research. Bailey and one of his undergrads are actually conducting more research, this time using neuroimaging to measure arousal, a technique that they suggest in this paper. The results of that study are not currently available, though.

In addition to the problems with the conclusions they draw from the study, there are problems with the study itself. The biggest problem is that all of the men were recruited through gay and alternative magazines (though they do not report how many were recruited from each). It's quite reasonable to assume that bisexual men who regularly read gay magazines are more aroused by men than women. This is another instance of the recruitment problem that plagues much of the research on sexual orientation. With a relatively small and likely unrepresentative sample, it's not clear how generalizable the results are. Another problem, which they do mention, is the crudeness of their measure of arousal. While plethysmography is the most reliable method currently available, roughly one third of the men in this study (and others that use the method) had to be excluded due to failure to detect significant differences in arousal between the sexual and non-sexual videos. Better measures might show more subtle differences in arousal levels between gay, straight, and bisexual men. Imaging techniques, if they show converging results, could help, though imaging data would be difficult to interpret.

The point, then, which is completely lost in the NYT's article, is that the question, "Does male bisexuality exist?" is not answered by this study. The results are interesting, and certainly make the case for further research, but that's about all they do. It would be a serious mistake to dismiss self-reported sexual attraction and orientation based on one preliminary study. Instead, we should do what scientists should always do, and what the authors suggest: explore all of the possible explanations for the data, while continuing to attempt to gather better data.

UPDATE: One more comment on Bailey's quote in the NYT article, in which he said, "For men arousal is orientation." This seems to be a hypothesis, derived from the evidence showing that for both gay and straight men, self-reported sexual orientation, subjective arousal, and physical arousal are all highly and positively correlated (the correlations are up around .95). However, this theory makes a prediction about the correlation of self-report, subjective arousal, and physical arousal for bisexual men, and this prediction was not supported by the data. Instead of admitting this, Bailey instead sticks to his hypothesis, and offers an explanation for the bisexual data that is not justified by that data -- that male bisexuality does not exist. A more scientif approach would be to note that the prediction is not supported by the data, and then call for further data to attempt to either bridge the gap between the hypothesis and the data (as the research article actually does) , or suggest alternative hypotheses. Given the data we do have, from Bailey's own experiment, the hypothesized identity between sexual orientation and arousal in men has no more, or depending on your interpretation, less support than the existence of male bisexuality (which is supported by self-reported sexual orientation and the subjective arousal data).

^* The male-female videos were only included to ensure that straight men were not simply averse to homosexual sex. Since all males (gay, straight, or bisexual) showed physical arousal to all types of video, and since straight men showed high arousal to the female-female videos, the male-female condition is really unnecessary. The female-female video is a better for comparison to the male-male video, because it does not involve any member of the unpreferred sex for straight men, or the preferred sex for gay men.

Zombies and Politics

In lieu of substantive posting (there's some coming, I promise -- if you want to be prepared, you can start by reading this), here's a funny opinion article on the movie "Land of the Dead." Whose idea was it to use zombies as political symbols? Anyway, here's the funniest part:

The greatest irony here is that, were Romero not obsessed with having the zombies be the underdog heroes of his story, there are several other prime targets in today's political world just begging for the kind of rich, symbolic commentary that only zombie movies can provide.

For example, consider the rhetorical position of many in the right wing who feel oppressed by the tattered remnants of the left. Republican politicians claim their agenda is being thwarted, despite the fact that they control the presidency, both houses of Congress, and a soon-to-be-increasing majority on the Supreme Court. Hawkish neocons claim that, despite getting their way in every key decision related to the Iraq war, it will be liberal dissent that dooms the mission. Conservative Christians, despite being spectacularly influential in the government and society at large, claim they're being persecuted by secular liberals.

Like the zombies of "Land of the Dead," the right wing seems content to live out an empty parody of American life, happily pursuing the surface appearance of days gone by until disturbed by outside forces. Then they unite, marching forward, becoming better organized, smarter and more dangerous, until at last they overwhelm all those who foolishly place themselves above the fray.

Only once all resistance has been destroyed do they return to their former state of existence, a vast monoculture that stretches from sea to shining sea. (Except for a few wacko holdouts in Canada.)

The thing is, I thought Rove, Limbaugh, Hannity, Ann Coulter, and the like really were the right-wing undead. Heck, Coulter even looks like a zombie.

My First Meme

I've been blogging for close to a year, now (9 months, to be exact), and I've yet to participate in a single one of those infernal blog memes, but I'm going to break down and do this one. This is partly because it was started by Richard, whom I like, and continued by Lindsay and Brandon, whom I also like. It's also because Richard touts it as a potentially rich source of data for social scientists. I'm not so sure about that in this case (the political test, at least, seems kind of silly), I've been very interested in the dynamics of internet communities, lately, and I want to encourage blogger participation in projects like this one. Trust me, in the next few years, sociologists and social psychologists are going to be all over the blogosphere, conducting research that requires blogger participation. We might as well get used to it now.

The meme involves two tests, the links to which are at the end of this post. The first is a personality test (I recommend the long one -- I took both, just to see how similar the answers were, and while the trends were the same, the numbers were sometimes quite different). My results are not really surprising. I'm introverted, liberal, sympathetic, messy, and a melancholy, brooding intellectual who loves art. Much of that you could probably have guessed from this blog. The second test is a political test. Not much of a surprise there, either, with me being fairly far to the left, and down at the libertarian end of the spectrum. So, without further ado, here they are. At the end, you'll find the instructions to participate in Richard's meme yourself.

Survey:

Age: 29
Gender: Male
Location: United States
Religion: None
Occupation: Scientist
Began blogging (dd/mm/yy): 09/03/05

Political Compass results
Left/Right: -5.63
Libertarian/Authoritarian: -7.54

IPIP-NEO results

EXTRAVERSION: 19
Friendliness 10
Gregariousness 2
Assertiveness 70
Activity Level 34
Excitement-Seeking 41
Cheerfulness 28

AGREEABLENESS:98
Trust 29
Morality 94
Altruism 90
Co-operation 84
Modesty 96
Sympathy 99

CONSCIENTIOUSNESS: 41
Self-Efficacy 85
Orderliness 1
Dutifulness 45
Achievement-Striving 79
Self-Discipline 28
Cautiousness 71

NEUROTICISM: 35
Anxiety 18
Anger 18
Depression 87
Self-Consciousness 81
Immoderation 14
Vulnerability 9

OPENNESS TO EXPERIENCE: 99
Imagination 84
Artistic Interests 95
Emotionality 99
Adventurousness 98
Intellect 91
Liberalism 98

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Instructions (to join in the experiment):

1) Take the IPIP-NEO personality test and the Political Compass quiz, if you have not done so already.

2) Copy to the clipboard that section of this post that is between the double lines, and paste it into your blog editor. (Blogger users may wish to use 'compose' mode to preserve formatting and hyperlinks. Otherwise, be sure to add hyperlinks as necessary.)

3) Replace the answers in the "survey" section below with your own.

4) Add your blog information to the "track list", in the form: "Linked title - URL - optional GUID".

5) Any additional comments should go outside of the double lines, including the (optional) nomination of bloggers you wish to pass this experimental meme on to.

6) Post it to your blog!

=============================================================

Track List:
1. Philosophy, et cetera - pixnaps.blogspot.com - pixnaps97a2
2. Mixing Memory

One Team, Two Team(s), Red Team, Blue Team

Once upon a time, I wrote:

I have to admit, I don't think the evolution v. creationism debate is worth having. There is simply no version of creationism, from young-earth creationism to intelligent design theory, that has the scientific merits to warrant a scientific debate. Still, if people must have such a debate, can't they at least try to do so civilly? All of the evidence speaks to the contrary.

The latest blog war over comments by Mark Kleiman about the tone of the evolution-creationism debate have proved that I was even more right than I thought I was. It turns out that those of us on the side of science can't even be civil to each other.

I'm not really sure why Kleiman's remarks have created such a stir. To be sure, the "red team" and "blue team" labels are not only inaccurate, but silly, but for the most part the post seems to me to be fairly innocuous, even where it's wrong, but since most of the people who comment on his post adopt those labels, that can't be the source of the blog controversy. Kleiman starts out with an undeniably true assertion, namely that the debate over evolution is not about science, but about culture. For many on Kleiman's "red team," or more accurately, for many conservative Christians, evolution is a symbol of what they see as secular moral, social, and cultural trends, ranging from more open-minded sexual attitudes to the removal of the Ten Commandments from courtrooms in Kentucky and Alabama. These people aren't anti-science across the board; they're just as likely to jump on the science bandwagon when it means receiving medical treatment, logging onto a computer to post a scathing anti-evolution blog post, or otherwise serves their interests or ideology, as are those on the "blue team," which is to say, those who are not Biblical literalists or ultra-conservative evangelicals (there are plenty on the "red team," as usually conceived, who don't fall within those categories, which is why Kleiman's labels are so silly). Since the issue is a moral/cultural one, that's where we should be addressing it.

Kleiman goes from there to argue that we who are the side of evolution should be more civil when talking with those on the side of creationism or Intelligent Design, because we have to respect their cultural and moral world-view. Once again, Kleiman is right. We do have to be more respectful. However, he does seem to have the reasons for this respect wrong, and this seems to be where people like Dr. Myers and someday-Dr. Beyerstein start to find Kleiman's post offensive. As Lindsay notes in her second post, "They deserve the same courtesy as anyone who is advancing a view in a public debate, but they don't deserve any special deference from us because their beliefs are well-intentioned and/or faith-based." I might also add that they deserve the same respect from us liberals as we would give any other culture. In particular, we should respect their right to hold a world-view different from ours. None of this, however, as both Lindsay and Kleiman note, means we should tolerate the bad behaviors that arise from that world-view, which include trying to sneak their religion into the classroom.

It's important to note that even in this discussion, some of us "blue teamers" haven't really been doing this. Dr. Myers (several others have picked on him, and he's handled it well, so I will use him as an example) is quick to point out that he doesn't mean all Christians when he attacks creationists and IDers, but because his rhetoric is often very harshly worded and, at times, a bit overly general or at least without argumentation, as for example when he writes: "…so how can he then turn around and say that Genesis is "providing a potentially powerful prop to moral behavior"? It clearly isn't. It is a historical, empirical, ongoing failure as a moral force for good," or frames the debate as one between "reason" and "superstition", it's easy to understand why some might not see it that way. Again, I don't think that Dr. Myers' is attempting to disparage all religion, or even all Christianity, but I can certainly see how someone might interpret him as doing so, and in reality, plenty do, including some on the "blue team." If Kleiman is arguing that we have to be careful to be respectful of the world-views, even if we disapprove, and openly express our disapproval, of some of the world-view-induced behaviors, then we have to watch our tone, and the scope of our language.

Everyone seems to agree on this, even if they don't always practice it to the same degree, and Kleiman's someone convoluted arguments for this position, about Genesis, faith, and the like, can't possibly be the reason for the starting of a blog war. There are other candidates, though. For instance, Dr. Myers rightly takes exception to this little nugget from Kleiman:

Insofar as middle-school Darwinism asserts that each of us is merely an animal of a particular species, fundamentally like animals of other species, it undercuts both halves of that double-barreled moral proposition. If I'm merely an animal, why shouldn't I act like one if I feel like it? And, if you're merely an animal, why shouldn't I beat you up, if I'm so inclined and bigger than you are?

What Kleiman should have concluded from this is that education, which is a form of respect, is what is needed. If the "red teamers" believe that evolution implies "middle-school Darwinism," then science educators have failed, and need to get off their collective ass and start giving people a more accurate representation of evolution and modern biology. This is also where we can begin to bring the discussion around to the cultural/moral issues that have made it so contemptuous. We can point out to creationists that evolution implies that we are all related to each other, that we are brothers or sisters to each and every human being, and thus that from a world-view that includes evolution we can derive the moral views of Christianity, from thou shalt not kill to the golden rule, just as readily as we can scripture and faith. We also have to do a better job of pointing out that belief in evolution does not preclude belief in scripture, and a moral world-view derived from faith. In short, what Kleiman should have said is that the fact that people on the "red team" accept the "middle-school Darwinism" version of evolution is where all of the problems begin, and the greatest respect we can show them is to disabuse them of this misconception. Perhaps it is because Kleiman nowhere makes this point that so many have criticized his entire post.

Even so, I hope that most of us agree with Kleiman's larger point about the evolution-creationism debate, or at least the part that he gets right, which is that it is a debate over a cultural issue, and if we're going to participate in the debate, we should debate it on cultural terms. No amount of scientific reasoning will convince people who fear evolution for cultural reasons. I also think that most of us agree with what I take to be Kleaiman's point at the end of the post, namely that we should point out, again and again, to the "red team" that their justifications of torture, extreme nationalism (in the form of "America first"), and their support for a war of choice, go against their stated moral world-view, whether it is derived exclusively from scripture or not.

In the end, then, I hope that the people on the "blue team" who have been criticizing Kleiman at least recognize what he gets right, and notice where they too are failing, through their observation of what Kleiman leaves out.

Evolutionary Psychology vs. evolutionary psychology

A psychologist who is writing a book on evolutionary psychology (I don't want to mention his name, since he hasn't given me permission to do so) wrote me today with the following:

I recently discovered your blog (via Cognitive Daily), and read two of your skeptical about EP pieces. What I'm puzzled about here is how critics of EP (including Buller and Sharon Begley in the Wall Street Journal) hardly ever mention (or seem to be aware of) the rival version of EP coming out of human behavioral ecology (as found, e.g., in Barrett, Dunbar, & Lycette, Human Evolutionary Psychology, Princeton UP). They, too, reject massive modularity but maintain a thoroughly Darwinian approach to understanding human behavior.

Any comment you have on this point would be much appreciated.

I responded to him in email, noting that the reason the negative focus has been on one particular strand of evolutionary psychology is that it is that strand that gets all of the attention in the popular press. I mention all of this, though, because his email made me realize that with the exception of my last post on the topic, I haven't really distinguished between the different evolutionary approaches in psychology. To be fair to Buller, though, he has in fact mentioned the distinction. He's quite careful to make it in his opening chapter, even going so far as to use Evolutionary Psychology, with initial capitals, to refer to the Cosmides, Buss, and Pinker variety that both he and I criticize, and evolutionary psychology, in all lowercase, to refer to evolutionary approaches to human behavior and cognition in general. They are quite distinct, and anyone who is interested in alternative approaches can choose from a variety of easily accessible resources from which to learn. I've heard that the Barrett et al. book is quite good, and I've bought it, but haven't read it yet, so I can't really recommend it. Instead, in this post I'll link to a few other resources that approach psychological issues from an evolutionary perspective that is quite different from that of Tooby, Cosmides, and the like, or at least does not entail that perspective.

• First there is the strain of evolutionary psychology that comes out of sociobiology. The only book I've read on the topic, and therefore the only one I can recommend, is John Alcock's The Triumph of Sociobiology. However, there are several others out there, and if that book doesn't do it for you, I'm sure you can find one that does.

• One of the most interesting, hotly debated, and fashionable topics in evolutionary psychology (lowercase version) today is the evolution of language. There area all sorts of books out there now on the topic. My favorite is Ray Jackendoff's Foundations of Language: Brain, Meaning, Grammar, Evolution. This isn't a book about the evolution of language, and you have to wade through 7 chapters of some pretty heavy linguistics (an experience akin to being subjected to several different types of medieval torture at once) to get to the 30-page chapter on the evolution of language, but the anguish you experience getting there is well worth it, because he presents one of the most level-headed and plausible accounts of the evolution of language out there. If you don't have the stomach for the linguistics, or simply don't want to read a long book by an academic, you can also check out his Trends in Cognitive Sciences paper from a few years ago, in which he gives a glimpse of his view. Also, it may interest some of you to know that Jackendoff has used his approach to the language faculty to study music, and even written about potentially innate capacities related to musical cognition, in this manuscript for instance.
  
  Of course, if you're reading up on the evolution of language, you have to read Derek Bickerton's Language and Species, and you should probably read Pinker and Bloom's 1990 Behavioral and Brain Sciences paper, because both have been incredibly influential and are discussed in virtually every writing on the topic.
  
  With Bickerton, Jackendoff, Pinker, and Bloom you will get a set of views on the evolution of language that all fall within the Chomskyan tradition. For slightly (or in some cases dramatically) different perspectives, you might want to read Robin Dunbar's book, Grooming, Gossip and the Evolution of Language. In that book, language evolution is said to be an adaptation to the increasing size of human communities, which makes the other forms of intimacy and communication (e.g., grooming) less effective for maintaining social bonds and retaining knowledge of social relationships and structure. In short, language evolved so we could gossip. Then there's Peter MacNeilage's frame/content theory of language evolution, which he presents in this BBS paper. If you're partial to the Chomskyan versions in the sources above, MacNeilage's account might seem downright wacky, but you should still find it interesting. If you're like me, on the other hand, you'll find it to be a welcome relief.
  
  Finally, if you just want a general book on the evolution of language, the compilation Approaches to the Evolution of Language : Social and Cognitive Bases, edited by Hurford et al., which contains chapters by Bickerton, Dunbar, and MacNeilage, along with several others, including a little John Locke thrown in for good measure, is an excellent resource.

• Another very interesting area of research is cultural evolution and the evolution of culture. Robin Dunbar, along with a few others, recently edited a book on the topic, titled The Evolution of Culture: An Interdisciplinary View. You'll get a lot of primatology and other non cog-sci perspectives in the book, which is a good thing, since cognitive scientists tend to have a pretty rudimentary knowledge of evolution, which is why we have Evolutionary Psychology (initial caps version) in the first place.
  
  Much of the interesting work in this area by cognitive scientists themselves has been in the area of religious cognition, and one of the foremost researchers who takes an evolutionary approach to issues of culture is Scott Atran, whose book In Gods We Trust: The Evolutionary Landscape of Religion is both interesting and full of great citations if you want to follow it up with some more thorough research. One of the interesting ideas to come out of the work in the evolution of religion is the existence of an agency-detection module. Note, however, that the existence of an agency-detection module does not in any way imply massive modularity. Atran's related work on folk biology, mostly conducted with Doug Medin, as well as similar work by other cognitive scientists, is discussed in the book he and Medin edited, titled simply Folkbiology, which may also be of interest to those seeking non-Evolutionary Psychology evolutionary psychology.
  
  Then there's one of my favorite cognitive scientific books, by one of my favorite cognitive scientists, Michael Tomasello's The Cultural Origins of Human Cognition. This book is an anti-evolutionary psychologist's guide to evolutionary psychology. In it, he argues that the primary cognitively-significant adaptation in human evolutionary history was an advanced capacity for mimesis. It is through this capacity that we are able to actively teach our young, and ultimately develop a cumulative culture. It is through this capacity, and the accumulation of cultural knowledge that it allows, that we developed our capacities for language and complex reasoning, along with virtually every other exclusively human cognitive ability. The book, while excellent, does have its weak points. Fortunately, Tomasello has been actively working on his theory. For a later treatment, you can read his paper (which I believe is still in press at BBS, which means it might actually be published at some point in the next 35 years) titled "Understanding and sharing intentions: The origins of cultural cognition."
  

That's probably enough for now. With this list, you should be able to access a wide variety of evolutionary psychological views that are independent from, if not diametrically opposed to those of the Cosmides, Buss, and Pinker crowd. Now I feel like I've done my duty in making an important distinction, one that I've failed to explicitly make in posts in the past, and can already sense my karma improving.

By the way, if you're reading this and are more familiar with some of these literatures (particularly sociobiology) and know of some good sources, leave me a comment and I will be sure to add an update.

The Epistemology of Neuroimagining

Via the Online Papers in Philosophy blog, I discovered a nice paper by William Bechtel titled, "The Epistemology of Evidence in Cognitive Neuroscience." In the paper, he discusses in some detail, and with great examples, the ways in which neuroscientists have used three different methodologies: lesion/deficit studies, single-cell recordings, and neuroimagining (PET and fMRI in particular). The first two methods have been used for decades in neuroscience proper, and with a great deal of success. Single-cell recording studies, for instance, have painted an incredibly thorough picture of the visual cortex, especially its early parts (and most especially V1, about which we probably know more than we do about any other brain area). Still, both lesion and single-cell recording methods have their limits (it's unlikely that either will tell us much about higher-level cognitive processes anytime soon), and this has led cognitive neuroscientists to rely heavily on neuroimagining techniques. In my last post, I made some pretty snide remarks about neuroimagining studies (heck, the whole post was a snide remark about neuroimagining studies). I thought it might be appropriate, then, to link to a paper which does a good job of discussing the problems with neuroimagining techniques, and in particular, the problems with the subtraction method that is most commonly used in cognitive neuroscience.

If that's not enough for you, you might also check out Sartori and Umilta's excellent paper on the subtraction method, and alternative methods, titled, "How to Avoid the Fallacies of Cognitive Subtraction in Brain Imaging." It was published in Brain and Language in 2001 (vol. 74, pp. 191-212), but I can't seem to find an online version that doesn't require a subscription. If anyone knows of one, please let me know.

And finally, while you're reading Bechtel, you might also check out his very interesting paper on the symbolic-connectionist debate, which was also linked on the Online Papers in Philosophy blog. That paper is here.

Orgasm in the Brain, or Porn for Neuroscientists

Sometimes I really think I went into the wrong area of cognitive science. I mean, I'm not really a big fan of cognitive neuroscience; I tend to think it's a faddish discipline that tells us little more than that cognition happens in the brain (a joke that I stole, but since none of you are likely to know the person from whom I stole it, and since he probably isn't reading this, I'm going to pretend it's my own). But when I read about studies like the one I'm about to describe, my opinion of imaging research changes dramatically, not so much because I think it's more scientifically sound, but because I would really like to run the experiments.

The research, which I discovered through John Hawks (my new source for all things cool and neuroscientific), involves looking at the brain regions that are active during sexual arousal and orgasm. The article that John links in his post is mostly about a study on female orgasms, and more specifically on the differences between the brain areas that are active during faked and real female orgasms. That research is so new that I can't find it on any of the article databases that I usually use. The research on male orgasm, however, was published a couple years ago, so I can talk about that^*.

Here is the background: several studies of brain activation, or dysfunction as a result of brain lesions, during ejaculation have been conducted using rats, along with at least one study using nonhuman primates. These studies have been inconclusive with regard to the specific functions of different brain regions during ejaculation, and there are differences between the activation in rat and primate brains. These two facts limit our ability to draw conclusions about brain activation in human males during ejaculation from the animal literature. Now that we have some fairly good imaging techniques (in particular, fMRI and positron emission tomography, or PET), though, we can look at brain activation in humans during ejaculation directly, and bypass the animal literature altogether.

How, you might ask, do we get people to ejaculate while in a PET scan machine? Well, that's where this research gets interesting (for me, at least), and what makes me think I should have gone into the neuroscience of sex. Here is the description of the experiment, from the methods section of the above-linked paper:

The volunteers were asked to perform the following tasks twice: rest, erection, sexual stimulation, and ejaculation induced by sexual stimulation. To minimize motor activity by the volunteer during the scan, sexual stimulation was provided by his female partner by means of manual penile stimulation in the tasks stimulation and ejaculation. Manual stimulation was continued throughout ejaculation. The volunteer's head was maintained in position with a head-restraining adhesive band, and, to minimize visual input, volunteers were asked to keep their eyes closed.

Seriously, does this not sound like neuroscientist porn (complete with bondage)? If sessions were taped, how much do you want to bet that the videos are currently being sold on some neuroscience email group? Anyway, in order to make sure that the volunteers could perform the task, it was suggested that for a few weeks prior to the experimental session, they practice at home, "especially regarding minimizing head and limb movements." So the experiments were probably fun for the participants as well.

Once they had them in the machines, they took scans during stimulation and during orgasm, and later analyzed the data by comparing the stimulation scans to orgasm scans in 11 volunteers (only 8 of the 11 could be used for some analyses, for reasons discussed in the paper that are simply too uninteresting to mention in a blog post).

Most of the results are unsurprising. They found the strongest activation during ejaculation in the mesodiencephalic transition zone (MTZ), which is comprised of several regions involved in the brain's rewards system, and its dopamanergic reward system in particular. Specifically, the ventral tegmental area is part of the MTZ, and is associated with the pleasurable sensation people get from drugs like heroin and cocaine. Thus, orgasm and heroin highs appear to use the same brain structures in males. Activation was also found in the right thalamus and neighboring regions, which are associated with arousal and "visceral sensory responses." The right parietal lobe, which is also associated with sensation, was also active during ejaculation. All of this sounds about right. The same goes for the activation found in certain parts of the visual system, including the precuneus (visual memory) and the secondary visual cortex, because as the authors note, most of the volunteers reported using visual imagery during the session.

Finally, and perhaps this is a bit surprising, they found a lot of activation in the cerebellum. Traditionally, the cerebellum has been thought to be primarily involved in movement, but the volunteers' movements were restricted, and their female partners were doing all of the work. Recently (over the last decade or so), researchers have begun to realize that the cerebellum is involved in a lot more than just movement, though. In particular, it appears to be heavily involved in emotion, and the authors of the article explain its activation by arguing that cerebellum activity during ejaculation produces a "rush" similar to that experienced during other rewarding activities, such as heroin use and listening to pleasant music.

The researchers did find deactivation in two areas, the amygdala and entorhinal cortex. These areas, especially the amygdala, are also associated with emotion. The amygdala is particularly associated with fear responses, and decreased activation in this area has been shown to cause euphoric states associated with drug use and intense love. So, the corresponding activation of the cerebellum and deactivation of the amygdala appear to cause the intense euphoric emotional state associated with orgasm.

Thus, in sum, human male brain activity during orgasm looks a lot like it does when we're doing drugs. The authors also note that it also looks more like nonhuman primate activation than rat activation, a fact which probably ruins a lot of potential jokes. Furthermore, the bulk of the activation during ejaculation was in the right hemisphere, which makes me wonder whether left-handers have stronger orgasms (a speculation that is completely unwarranted by the data, but I'm pretending to be a cognitive neuroscientist now). Mostly, though, given the terrible resolution (both spatial and temporal) of the imaging techniques that are available today (both PET and fMRI were used in this study), what we've really learned is that male orgasm causes brain activation. The authors themselves note that the resolution isn't sufficient to distinguish the activation in different parts of the MTZ, and it's hard to say exactly which of the functions of the other multi-functional brain areas are involved, because we can't tell exactly which parts, much less which neurons, are active. As is usually the case with brain imaging studies, the conclusions involve inferences to the best theoretical bias. Still, we've got to start studying the role of the brain in male orgasm somewhere, sometime, and even if I don't think this sort of research tells us a whole hell of a lot, I sure wish I could get in on it.

^* Just in case you're new to the blog, or you've forgotten, it's my policy not to comment on research that I only know about through articles in the popular press, because the press generally does a horrible job of reporting about science, especially cognitive science.

Why Is Yawning Contagious?

Today as I was riding home from campus on the bus, I was talking on the phone, and my interlocutor yawned. Almost immediately, I yawned as well. She made a joke about it, and I said that it wasn't my fault, because yawning is contagious -- when you see or hear someone yawn, you tend to yawn as well. I thought that was a well-known fact, but apparently she had never heard it, or noticed it before, so my first instinct was to prove that it was true by explaining to her why it happened. Then I realized that I had no idea why it happened. So I decided that when I got home, I would look it up. Let it never be said that I am not a geek.

So, I got home and started researching the topic, and quickly discovered that I was not alone. It seems that nobody's sure why yawning is contagious. There do appear to be some differences in individuals who are susceptible to contagious yawning and those who are not¹. In particular, contagious yawners score lower on the Schizotypal Personality Questionnaire, which was designed to measure the symptoms of Schizotypal Personality Disorder. These symptoms involve less social and self-awareness, along with schizophrenia-like symptoms such as altered or unusual perceptions, particularly in social contexts, which can lead to paranoia. Lower scores on the test indicate lower levels of schizotypal symptoms. Contagious yawners also performed better when answering questions about stories designed to test for theory-of-mind ability. Finally, they also had much faster reaction times when asked to identify their own face presented on a computer screen. Steven Platek and his co-authors argue that these findings, that contagious yawners score lower on the Schizotypal Personality Questionnaire, and show better theory-of-mind and self-recognition performance, indicates that self-awareness and empathy underlie contagious yawning.

This would fit with what we do know, and can easily see about contagious yawning: it is automatic and unconscious. We don't try to yawn when we see or hear someone else do so; we just do. Self-recognition and theory-of-mind mechanisms are generally fast, automatic, and unconscious, and thus it is plausible, given the data described above, that they are involved in contagious yawning. But the data I described above is pretty thin, and is certainly open to alternative interpretations. To find out for sure, I looked to neuroscience. Unfortunately, when I got there, the picture got a bit muddier. In a very recent study (published in February), researchers had participants watch videos of yawning while they were scanned using functional magnetic resonance imaging (fMRI)². They found that people who watched the yawning videos had increased activation in the right posterior superior temporal sulcus and in the anterior superior temporal sulcus in both hemispheres. These areas are associated with the processing of social information, and the increased activation in these areas thus fits with the theory that social awareness may underlie contagious yawning. However, they did not find activation in Broca's area, which is thought to house the human version of the mirror neuron system, and believed to be associated with theory of mind. Furthermore, they found that participants who watched the yawning videos showed decreased activation in the left periamygdalar region. This area of the brain is associated with the recognition of emotional facial expressions.

These last two findings are confusing, and perhaps inconsistent with Platek's theory. It appears that, while social information processing does underlie contagious yawning, action and emotion recognition, which are parts of our theory-of-mind abilities, are not associated with contagious yawning. However, to make things even more confusing, Platek and his colleagues have conducted their own imaging study³. When contrasted with laughing and neutral videos, yawning videos caused increased activation in the posterior cingulate and precuneus, areas associated with, among other things, autobiographical memory, emotion, and self-judgements. Thus, Platek's findings are consistent with his theory, but inconsistent with the only other imaging study of contagious yawning.

The take home message, then, is that it's not quite clear what causes contagious yawning. Sure, we can say with a high degree of certainty that social-information processing is involved, but that seems obvious. What's less obvious is what else is involved. Are empathy and self-awareness involved? The neuroimaging data is too inconsistent to say for sure.

However, if it turns out that empathy and self-awareness are involved in contagious yawning, then another finding becomes much more interesting. It was previously thought that, while yawning occurs in many animal species, only humans yawned contagiously. It turns out, chimps may yawn contagiously as well. James Anderson and his colleagues published a paper in late 2004 in which they presented six adult female chimpanzees with videos depicting facial expressions, including yawning. When the videos showed yawning, two of the six chimps yawned more frequently than when watching other expressions⁴. While this is obviously a preliminary finding, if it turns out that chimps do yawn contagiously, and that contagious yawning requires empathy and self-awareness, as Platek argues, then we would have strong evidence that chimps are self aware and have some level of theory-of-mind/empathy.

¹Platek, S.M., Critton, S.R., Myers, T.E., & Gallup, G.G., Jr. (in press, 2003). Contagious yawning: The role of self-awareness and mental state attribution. Cognitive Brain Research, 17(2):223-7.
²Schurmann, M., Hesse, M..D, Stephan, K.E., Saarela, M., Zilles, K., Hari, R., & Fink, G.R. (2005). Yearning to yawn: the neural basis of contagious yawning. Neuroimage, 24(4), 1260-1264.
³ Platek, S.M., Mohamed, F.B., & Gallup, G.G. Jr. (In Press). Contagious yawning and the brain. Cognitive Brain Research.
⁴Anderson, J.R., Myowa-Yamakoshi, M., & Matsuzawa, T. (2004). Contagious yawning in chimpanzees. Proceedings of the Royal Society: Biological Sciences, 271, Biology Letters Supplement 6, S468 - S470.

Your Cat Could Change Your Personality

A few years ago, I read about this strange parasite that cats pass to rats, and rats pass back to cats, that caused infected rats to lose their fear of cats (the title of the original paper was, "Fatal attraction in rats infected with Toxoplasma gondii"¹. Now researchers have demonstrated that it can have more subtle effects when humans become infected. First, I learned that researchers showed that those who are infected with the parasite, whom researchers had known showed slower reaction times in laboratory experiments, were 2.65 times more likely to be in car accidents than uninfected people. Now I've learned that they've also discovered even stranger effects on people's personalities (thanks to John Hawks, who linked this article). In 1999, this paper reported the differences found in women who were infected. This is from the abstract:

The subjects with latent toxoplasmosis had higher intelligence, lower guilt proneness, and possibly also higher ergic tension. The difference in several other factors (desurgency/surgency, alaxia/protension, naivete/shrewdness, and self sentiment integration) concerned changes in the variances, rather then the mean values of the factors.

Then I found this 1996 paper which showed than men who were infected were more likely to disregard rules, were less trusting and tolerant, and more jealous, reserved, critical, detached, and guilt prone. Infected women, on the other hand, were more "warmhearted," outgoing, easygoing, trusting, accepting, tolerant, astute, worldly, and polished. In other words, the effects on men and women were in entirely opposite directions. Even more disturbing was the 2003 paper reporting research using military personell that showed infected men to be more impulsive, extravagant, and disorderly (they looked more ragged), along with having lower IQs, lower education levels, and lower levels of novelty seeking.

All this sounds pretty bad for us men, and perhaps not that great for women either. Men become dirty, dogmatic recluses, and women become naive, outgoing, and promiscuous (some of the evidence indicates that they have sex with more men). The authors of the 2003 paper (the first author is the same in each of the papers that I've linked) suggest that the specific behavioral differences in infected men may indicate that the parasite affects the dopamanergic system, which may be why there is a link between infection and schizophrenia.

It turns out, though, that the most recent research indicates that the parasite may not be the cause of some of the behavioral differences. Instead, it appears that there are physical differences between infected and uninfected males that are unrelated to infection, and which may be related to decreased immune response to the parasite. These differences may also be associated with some of the behavioral differences, indicating that the differences may have existed in the individuals prior to infection. So, the parasite may not be causing people's personalities to change afterall. Or at least, it may not be causing all of the differences (e.g., IQ differences and differences in reaction times). The jury is still out, though, so for now, I'm going to be staying away from cats and cat people.

¹Berdoy, M., Webster, J. & Macdonald, D. (2000). Fatal attractions in rats infected with Toxoplasma gondii. Proceedings of the Royal Society of London (B) 267: 1591-1594.

Orac and Galileo

Via Brandon, I came across this excellent reply to the misgivings of a young creationist. Unfortunately, at the age of 14, his or her beliefs may be too set in stone to be altered by facts or reason. Still, Orac gives him both, and does so in an extremely respectful tone. Given the lack of civility that dominates the debate between science and religion, Orac definitely deserves recognition for the way he handle the situation.

I was particularly impressed with the way he ended the post, posing an extremely interesting and important question to the young creationist. Orac wrote:

I'd like to leave you with a few questions to ponder: If, as you almost certainly believe, God is indeed the source of all truth, why would He leave so much evidence scattered about His creation showing that the earth is billions of years old and that animals and plants evolved into different species over hundreds of millions of years if it were not the truth that this is so? Why would He endow humans with the intellect and desire to delve deeply into the mysteries of His creation to try to learn what His natural laws are, if the truth of creation and His natural laws are not the same as what His creation tells them? As a Christian, does it not make more sense to conclude, as the minister above (and others) do, that God set things in motion and evolution was His preferred mechanism to produce all the diversity of life on this planet?

This immediately reminded me of a point that Galileo made in his famous "Letter to the Grand Duchess Christina of Tuscany." In that letter, he defends his views concerning the relationship between the Earth and the sun against the criticisms coming from within the Church. His comments largely concern the relationship between science and religion, and I've often felt that the letter should be required reading for creationists. I won't post the whole letter, but here's a good chunk of it:

I think in the first place that it is very pious to say and prudent to affirm that the holy Bible can never speak untruth-whenever its true meaning is understood. But I believe nobody will deny that it is often very abstruse, and may say things which are quite different from what its bare words signify. Hence in expounding the Bible if one were always to confine oneself to the unadorned grammatical meaning, one might; fall into error. Not only contradictions and propositions far from true might thus be made to appear in the Bible, but even grave heresies and follies. Thus it would be necessary to assign to God feet, hands ans eyes, as well as corporeal and human affections, such as anger, repentance, hatred, and sometimes even the forgetting of` things past and ignorance of those to come. These propositions uttered by the Holy Ghost were set down in that manner by the sacred scribes in order to accommodate them to the capacities, Of the common people, who are rude and unlearned. For the sake of those who deserve to be separated from the herd, it is necessary that wise expositors should produce the true senses of such passages, together with the special reasons for which they were set down in these words. This doctrine is so widespread and so definite with all theologians that it would be superfluous to adduce evidence for it.

Hence I think that I may reasonably conclude that whenever the Bible has occasion to speak of any physical conclusion (especially those which are very abstruse and hard to understand), the rule has been observed of avoiding confusion in the minds of the common people which would render them contumacious toward the higher mysteries. Now the Bible, merely to condescend to popular capacity, has not hesitated to obscure some very important pronouncements, attributing to God himself some qualities extremely remote from (and even contrary to) His essence. Who, then, would positively declare that this principle has been set aside, and the Bible has confined itself rigorously to the bare and restricted sense of its words, when speaking but casually of the earth, of water, of the sun, or of any other created thing? Especially in view of the fact that these things in no way concern the primary purpose of the sacred writings, which is the service of God and the salvation of souls - matters infinitely beyond the comprehension of the common people.

This being granted, I think that in discussions of physical problems we ought to begin not from the authority of scriptural passages but from sense­experiences and necessary demonstrations; for the holy Bible and the phenomena of nature proceed alike from the divine Word the former as the dictate of the Holy Ghost and the latter as the observant executrix of God's commands. It is necessary for the Bible, in order to be accommodated to the understanding of every man, to speak many things which appear to differ from the absolute truth so far as the bare meaning of the words is concerned. But Nature, on the other hand, is inexorable and immutable; she never transgresses the laws imposed upon her, or cares a whit whether her abstruse reasons and methods of operation are understandable to men. For that reason it appears that nothing physical which sense­experience sets before our eyes, or which necessary demonstrations prove to us, ought to be called in question (much less condemned) upon the testimony of biblical passages which may have some different meaning beneath their words. For the Bible is not chained in every expression to conditions as strict as those which govern all physical effects; nor is God any less excellently revealed in Nature's actions than in the sacred statements of the Bible. Perhaps this is what Tertullian meant by these words:

"We conclude that God is known first through Nature, and then again, more particularly, by doctrine, by Nature in His works, and by doctrine in His revealed word."

From this I do not mean to infer that we need not have an extraordinary esteem for the passages of holy Scripture. On the contrary, having arrived at any certainties in physics, we ought to utilize these as the most appropriate aids in the true exposition of the Bible and in the investigation of those meanings which are necessarily contained therein, for these must be concordant with demonstrated truths. I should judge that the authority of the Bible was designed to persuade men of those articles and propositions which, surpassing all human reasoning could not be made credible by science, or by any other means than through the very mouth of the Holy Spirit.

Yet even in those propositions which are not matters of faith, this authority ought to be preferred over that of all human writings which are supported only by bare assertions or probable arguments, and not set forth in a demonstrative way. This I hold to be necessary and proper to the same extent that divine wisdom surpasses all human judgment and conjecture.

But I do not feel obliged to believe that the same God who has endowed us with senses, reason and intellect has intended us to forego their use and by some other means to give us knowledge which we can attain by them. He would not require us to deny sense and reason in physical matters which are set before our eyes and minds by direct experience or necessary demonstrations. This must be especially true in those sciences of which but the faintest trace (and that consisting of conclusions) is to be found in the Bible. Of astronomy; for instance, so little is found that none of the planets except Venus are so much as mentioned, and this only once or twice under the name of "Lucifer." If the sacred scribes had had any intention of teaching people certain arrangements and motions of the heavenly bodies, or had they wished us to derive such knowledge from the Bible, then in my opinion they would not have spoken of these matters so sparingly in comparison with the infinite number of admirable conclusions which are demonstrated in that science. Far from pretending to teach us the constitution and motions of the heavens and other stars, with their shapes, magnitudes, and distances, the authors of the Bible intentionally forbore to speak of these things, though all were quite well known to them. Such is the opinion of the holiest and most learned Fathers, and in St. Augustine we find the following words :

"It is likewise commonly asked what we may believe about the form and shape of the heavens according to the Scriptures, for many contend much about these matters. But with superior prudence our authors have forborne to speak of this, as in no way furthering the student with respect to a blessed life-and, more important still, as taking up much of that time which should be spent in holy exercises. What is it to me whether heaven, like a sphere surrounds the earth on all sides as a mass balanced in the center of the universe, or whether like a dish it merely covers and overcasts the earth? Belief in Scripture is urged rather for the reason we have often mentioned; that is, in order that no one, through ignorance of divine passages, finding anything in our Bibles or hearing anything cited from them of such a nature as may seem to oppose manifest conclusions, should be induced to suspect their truth when they teach, relate, and deliver more profitable matters. Hence let it be said briefly, touching the form of heaven, that our authors knew the truth but the Holy Spirit did not desire that men should learn things that are useful to no one for salvation."

The same disregard of these sacred authors toward beliefs about the phenomena of the celestial bodies is repeated to us by St. Augustine in his next chapter. On the question whether we are to believe that the heaven moves or stands still, he writes thus:

"Some of the brethren raise a question concerning the motion of heaven, whether it is fixed or moved. If it is moved, they say, how is it a firmament? If it stands still, how do these stars which are held fixed in it go round from east to west, the more northerly performing shorter circuits near the pole, so that the heaven (if there is another pole unknown to us) may seem to revolve upon some axis, or (if there is no other pole) may be thought to move as a discus? To these men I reply that it would require many subtle and profound reasonings to find out which of these things is actually so; but to undertake this and discuss it is consistent neither with my leisure nor with the duty of those whom I desire to instruct in essential matters more directly conducing to their salvation and to the benefit of the holy Church."

From these things it follows as a necessary consequence that, since the Holy Ghost did not intend to teach us whether heaven moves or stands still, whether its shape is spherical or like a discus or extended in a plane, nor whether the earth is located at its center or off to one side, then so much the less was it intended to settle for us any other conclusion of the same kind. And the motion or rest of the earth and the sun is so closely linked with the things just named, that without a determination of the one, neither side can be taken in the other matters. Now if the Holy Spirit has purposely neglected to teach us propositions of this sort as irrelevant to the highest goal (that is, to our salvation), how can anyone affirm that it is obligatory to take sides on them, that one belief is required by faith, while the other side is erroneous? Can an opinion be heretical and yet have no concern with the salvation of souls? Can the Holy Ghost be asserted not to have intended teaching us something that does concern our salvation? I would say here something that was heard from an ecclesiastic of the most eminent degree: "That the intention of the Holy Ghost is to teach us how one goes to heaven. not how heaven goes."

But let us again consider the degree to which necessary demonstrations and sense experiences ought to be respected in physical conclusions, and the authority they have enjoyed at the hands of holy and learned theologians. From among a hundred attestations I have selected the following:

"We must also take heed, in handling the doctrine of Moses. that we altogether avoid saying positively and confidently anything which contradicts manifest experiences and the reasoning of philosophy or the other sciences. For since every truth is in agreement with all other truth, the truth of Holy Writ cannot be contrary to the solid reasons and experiences of human knowledge."

And in St. Augustine we read:

"If' anyone shall set the authority of Holy Writ against clear and manifest reason, he who does this knows not what he has undertaken; for he opposes to the truth not the meaning of the Bible, which is beyond his comprehension, but rather his own interpretation, not what is in the Bible, but what he has found in himself and imagines to be there."

This granted, and it being true that two truths cannot contradict one another, it is the function of expositors to seek out the true senses of scriptural texts. These will unquestionably accord with the physical conclusions which manifest sense and necessary demonstrations have previously made certain to us. Now the Bible, as has been remarked, admits in many places expositions that are remote from the signification of the words for reasons we have already given. Moreover, we are unable to affirm that all interpreters of the Bible speak by Divine inspiration for if that were so there would exist no differences among them about the sense of a given passage. Hence I should think it would be the part of prudence not to permit anyone to usurp scriptural texts and force them in some way to maintain any physical conclusion to be true, when at some future time the senses and demonstrative or necessary reasons may show the contrary. Who indeed will set bounds to human ingenuity? Who will assert that everything in the universe capable of being perceived is already discovered and known? Let us rather confess quite truly that "Those truths which we know are very few in comparison with those which we do not know."

Ten Most Harmful Books

Thanks to Rob "Helpychalk," I discovered this wonderful list of the Ten Most Harmful Books of the 19th and 20th Century. It was put together by a conservative group, so some of the books were obvious choices. Number 1 is the Communist Manifesto, with Das Kapital at number 6. The list also provides some pretty big hints about the kinds of conservatives who did the ratings. For instance, Darwin made the Honorable Mention list twice, with The Origin of the Species and Descent of Man. Appparently evolution is pretty harful. The Kinsey Report came in at number 4 (number 4!), meaning that sex is only slightly less harmful than Marx, Hitler, and Mao (whose books are number 1, 2, and 3 respectively). I was excited to find that some of my favorite authors/books are there as well. Nietzsche's Beyond Good and Evil came in at number 9 (its description ends with, "The Nazis loved Nietzsche"), John Dewey made the list with Democracy and Education at number 5, and Michael Foucault, Simone de Beauvoir, and Theodor Adorno (with his book about authoritarianism, which links it to conservativism) all made the Honorable Mention list.

The descriptions of the books are great. I'll just give you a taste, from the description of Democracy and Education.

In Democracy and Education, in pompous and opaque prose, he disparaged schooling that focused on traditional character development and endowing children with hard knowledge, and encouraged the teaching of thinking “skills” instead. His views had great influence on the direction of American education--particularly in public schools--and helped nurture the Clinton generation.

Connecting Dewey and Clinton to make it clear just how harmful Dewey has been is ingenius. I'm a little confused, though, about the use of the adjectives "pompous" and "opaque" to describe the prose in Democracy and Education. It's generally considered one of his most easily read books, and while I doubt anyone would call Dewey a great writer, I've always thought that this book (especially compared to his early writings) was quite clearly written.

Buller, the Short Version

If you don't want to go out and buy Buller's book, you can read a shorter version of his critique of Evolutionary Psychology in his upcoming Trends in Cognitive Sciences paper, which is here. Notice the critique of the use of Wason selection tasks. As I said in yesterday's review, if you're familiar with the literature, you will be baffled.

Has Evolutionary Psychology Been Demolished? A Review of Buller, Chapter 4

Before I begin, I need to give a brief explanation of terminology (if I don't, I can guarantee you that Razib of Gene Expression will note that I should have). There are two senses of the label "evolutionary psychology," and since Buller is only addressing one, I will be as well. The first, broader sense, includes any psychology that takes evolution seriously, or includes evolutionary considerations in its explanations of psychological phenomena. The second, which is generally associated with Leda Cosmides, John Tooby, David Buss, and Steven Pinker, includes only those evolutionary psychologists who adhere to a certain set of tenets, including massive modularity, assumptions about the "environment of evolutionary adaptedness" (or the EEA), and a belief that the modern mind evolved in the EEA. To distinguish this second sense from the first, I will use Buller's convention or referring to it with capital letters (Evolutionary Psychology, Evolutionary Psychologists), and using only lowercase letters for the first sense.

If you've read through my archives (I can't imagine anyone has), or have been reading this blog for a while, you probably know that I am no fan of Evolutionary Psychology (EP). I'm not alone in feeling that way. Most cognitive scientists aren't fans. And we have good reasons not to be.

I'm also not a fan of attacking the scholarship of others without providing at least some semblance of a critique (in fact, I feel bad about doing just that in the previous post, even if everything I said is true, and I've offered more than a semblance of a critique of Lakoff in past posts). It's not always easy to avoid doing that where EP is concerned, as it stirs up a lot of emotions among cognitive scientists. To be honest, I've been guilty of some pot shots towards EP and its adherents in the past. It doesn't help that I harbor a deep personal animosity towards one of EP's most prominent figures (I won't mention any names, but you can ride him to work), an animosity built largely around my dislike for his research. However, even he is a very bright guy, and he works hard at what he does, as do most Evolutionary Psychologists. So, as scholars, I think we owe it to them, and any other scholars, to give reasons for any harsh words we may utter about their work. That's why I took Brian Leiter to task for his post entitled "Evolutionary Psychology Demolished." That post referenced a bad book review of a book that it's not clear Dr. Leiter has read, on a topic it's not clear Dr. Leiter is qualified to address (he may be, but he's given no indication that he is). But even my attack on Dr. Leiter's post made me feel a bit guilty, so I feel like I should say something a bit more substantial about the book reviewed in the article he linked.

It just so happens that I have read the book. My general policy is not to read books on EP, because in books, you can say just about anything you want, and Evolutionary Psychologists tend to do that more than most. Even carefully reviewed academic books are subjected to standards far below those of peer reviewed journals. I'm particularly reticent to read books on EP by philosophers (after reading the God-awful Furnishing the Mind, which I also got for free, I'm wary of any books on cognitive psychology by philosophers). But I got a copy of Buller's Adapting Minds for free, and I had heard about it through the grape vine, so I went against my general policy and read the book. It turns out that on the whole, it's a very good book. The first three chapters are excellent, and the chapters on Mating, Marriage, and Parenthood (chapters 5, 6, and 7) are very good, too.

But those areas of EP are its weakest. They are the areas with very little experimental work, and a heavy reliance on incredibly large and poorly controlled surveys. It's true that they are the most popular areas among the general public, but that's because they're the sexiest (sometimes literally). So, if you want to say that EP has been demolished, you have to do more than attack its weakest links. To do that, you have to critique its strongest points. And it goes without saying that from a methodological and theoretical standpoint, EP's strongest point is the work of Leda Cosmides, John Tooby, and their colleagues on social exchange. They use actual experiments, rather than surveys, and they've produced a great deal of challenging data. Buller addresses their work in Chapter 4 (which he co-wrote with Valerie Gray Hardcastle), and in my mind, that is the book's weakest chapter. If his weakest chapter is a critique of EP's best research, then it may be difficult to say that Buller has demolished EP. Furthermore, since Dr. Leiter wants "law-and-economics" folk to read this book to see how shoddy EP is as science, Chapter 4 is the most relevant to his purposes. It is the work on social exchange that has been seen as directly applicable to economics. Cosmides and Tooby have even written a paper on applications of EP to economics. So, if EP is to be demolished even for Dr. Leiter's purposes, Chapter 4 has to do the bulk of the work.

To see why it's important to critique the work of Cosmides and Tooby in order to show how misguided EP really is, it's important to understand the goals of EP, and how Cosmides and Tooby's work is integral to the accomplishment of those goals. Dan Sperber and Vittorio Girotto put it this way¹:

Evolutionary psychology--in its ambitious version well formulated by Cosmides and Tooby (e.g., Cosmides & Tooby 1987, Tooby & Cosmides 1992)--will succeed to the extent that it causes cognitive psychologists to rethink central aspects of human cognition in an evolutionary perspective, to the extent, that is, that psychology in general becomes evolutionary. The human species is exceptional by its massive investment in cognition, and in forms of cognitive activity--language, metarepresentation, abstract thinking--that are as unique to humans as echolocation is unique to bats. The promise of evolutionary psychology is thus to help explain not just traits of human psychology that are homologous to those of many other species, but also traits of human psychology that are genuinely exceptional and that in turn help explain the exceptional character of human culture and ecology. (p. 197)

However, most of the work done in evolutionary psychology so far is on aspects of human psychology that are not specifically human except in their details. Showing, for instance, how human preferences in mate choice are fine-tuned in the way the theory of evolution would predict is of great interest (see e.g., Buss 1994) but it can be done on the basis of a relatively shallow psychology.

Thus, Sperber and Girotto argue, if EP is to accomplish its goals, work like that of Cosmides and Tooby (CT from now on) on specifically cognitive, and specifically human characteristics must be at the forefront. I would further argue that the primacy of work like that of CT is paramount if EP is to accomplish the goal of making psychology evolutionary. If psychology were to become evolutionary in the manner of work by people like Buss, it would truly be a regression, rather than a progression, in psychological science. Even the area most adjacent to the EP research on mating and parenting, social psychology, has been using experimental methods for nearly a century. Thus, whatever theoretical gains the evolutionization (yes, I made that word up) of psychology might bring us, it would cancel them out with losses in methodological rigor. I've already seen this happening within the realm of EP itself. I've attended many job talks by graduate students and post docs. Those that presented experimental research were so undertrained in experimental methods that, when they presented their work, everyone in the audience who was not an Evolutionary Psychologist (and perhaps some who were) could do little more than roll their eyes. And these were the best applicants to the best EP program in the country, and thus were the best that EP's next generation had to offer. Thus, from both a theoretical and methodological standpoint, the work of CT, and their intellectual progeny, is integral to the aims of EP itself.

OK, enough of all that preliminary stuff. On to Chapter 4 itself. The chapter is not just about the work of Cosmides and Tooby, but about modularity in general (it also discusses theory of mind, which I'll get to at the end of this post.. It begins quite well, arguing that massive innate modularity is unlikely, if not unlikely, from the perspective of developmental neurobiology. He gives a detailed description of the development of the brain in the human fetus and soon after birth, and argues that the facts of this development argue strongly against the existence of a large number of innate cognitive modules. He also addresses some of the arguments for massive modularity, such as the one which Donald Symons once characterized by saying,

It is no more probably that some sort of general-purpose brain/mind mechanism could solve all of the behavioral problems an organism faces (find food, choose mate, select a habitat, etc.) than it is that some sort of general-purpose organ could perform all the physiological functions (pump blood, digest food, nourish an embryo, etc.).²

Buller points out that neural plasticity, and the way that it allows brain circuits to be shaped by experience, allows the brain to evolve as a general-purpose organ. In fact, given the dynamic nature of the environment of our evolutionary ancestors, neural plasticity is likely a more adaptive solution than massive modularity, which restricts the brain to a specific set of tasks. It's also a more likely solution, since modules would quickly become obsolete as the environment changed. He also addresses Pinker's argument for modularity, which compares all of cognition to language in the first section, noting that language is likely unusually complex, cognitively, and that we do many incredibly complex things that we obviously do not have modules for (like playing chess). Language is likely a bad analogy, then.

Overall, the theoretical and developmental discussion of massive modularity is very good. However, after that, he turns to the evidence for modularity, which consists almost entirely of CT's work on social exchange. Note, first, that while it may be that the brain is not massively modular (it isn't!), it is still possible that there are a few individual modules for specific cognitive tasks that did not change over long periods of our evolutionary history. It could be that a cheater detection module did evolve, even if it's not accompanied by a lot of other domain-specific modules. Thus, Buller's arguments against the massive modularity thesis of EP can't be used as a critique of social exchange theory³. Also, as Buller himself notes, theoretical arguments are great, but they only go as far as the empirical data, and as any good scientist will tell you, no matter how foolproof the logic of a theory sounds, if in the face of that theory the data remains recalcitrant, we have to let it go. If the data is most consistent with the existence of a cheater detection module like the one that social exchange theory posits, even though theoretical arguments against the existence of cognitive modules make a lot of sense, we, as scientists, are going to have to go with social exchange theory.

Buller devotes the bulk of chapter 4 to examining the evidence for a cheater detection module. Before I get to his critique of that evidence, though, I should probably summarize social exchange theory and the evidence for a cheater detection module. I've done it before, but since I'm too lazy to go back and find the posts, I can't expect anyone to actually read them.

In his classic 1971 paper titled "The evolution of reciprocal altruism,"⁴ Robert Trivers argued that in order for reciprocal altruism to evolve, two other capabilities must have been present: the ability to detect cheaters, and the tendency to reward reciprocators. This insight has been confirmed by several game-theoretic simulations⁵. Drawing on these arguments, Cosmides developed social exchange theory, which is designed to explain the evolution of reciprocal altruism in humans. As part of this theory, she hypothesized that humans have evolved a cheater-detection module that allows them to detect those who do take benefits without reciprocating. This cheater-detection mechanism would allow humans to satisfy Trivers' two requirements for the evolution of reciprocal altruism.

There is evidence of a cheater detection algorithm in several nonhuman species. The most frequently cited example (perhaps because it's just plain cool) comes from vampire bats. Apparently vampire bats will regurgitate excess blood so that other members of their group can eat it. Furthermore, they can tell when another bat is not regurgitating excess food, by looking at its fat belly. A fat belly and no regurgitation equals cheating, and bats will not regurgitate their food for cheaters⁶. In humans, however, it's a bit more difficult to detect cheating (a fact which is unfortunate for researchers studying cheater detection). According to CT, the complexity of detecting cheaters means that we must have evolved a mechanism specifically designed to do so. This mechanism would recognize social exchange situations, and activate the appropriate reasoning principles in order to detect any cheaters.

The evidence for the existence of such a module comes almost exclusively from experiments using multiple variants of a single task, the Wason selection task (see this post for my short description of this task). There are two relevant versions of this task, the descriptive and the deontic. The descriptive task uses an indicative conditional of the form "If p, then q," and the deontic form uses a deontic conditional of the form "If you do p, then you must also do q," or some variant thereof. One of the classic findings from Wason task experiments is the "content effect," in which people perform quite poorly on the descriptive version, and quite well on the deontic version. Cosmides argues that the increased performance in the deontic version is due to the fact that it activates the cheater-detection module, and thus allows people to use domain-specific reasoning mechanisms to solve the task, whereas the descriptive version requires the use of domain-general reasoning mechanisms.

It is to this argument which Buller replies in Chapter 4. He offers two criticisms of this research, one of which is a "big picture" criticism, and the other of which is a "devil in the details" criticism. Here is his description of the first, from pp. 171-172:

Cosmides derives the hypothesis of a cheater-detection module from Trivers's argument that reciprocal altruism is evolutionarily unstable unless parties to reciprocal exchanges of benefits have the ability to detect when someone is taking a benefit from them without providing them with a benefit in return. Reciprocal altruism concerns what Cosmides calls social exchanges, which occur when two individuals perform acts that benefit one another at a cost to each. Social exchanges are thus relations between two individuals, and cheating in social exchange involves benefiting from an act performed by another individual without performing an act that benefits the individual. Virtually all of the experimental results that purportedly provide evidence of a cheater-detection module, however, derive from selection tasks involving what Cosmides and Tooby call social contracts, which is a much broader class of phenomena than the class of social exchanges. [Emphasis in original.]

But wait, that's not how CT define social exchange. Here is how they define it⁷:

[A] situation in which, in order to be entitled to receive a benefit from another individual or group, an individual is obligated to satisfy a requirement of some kind (often, but not necessarily, at some cost to him- or herself). Those who are rationing access to the benefit impose the requirement because its satisfaction creates a situation that benefits them.

This definition is completely consistent with Trivers' analysis of reciprocal altruism, and completely consistent with the problems used to detect the cheater-mechanism in CT's experiments. If that doesn't seem obvious from the "beer" example in the post I linked above, here are some more to help make it clear:

• If you go canoeing on the lake, then you have to have a clean bunk house.
• If a man eats cassava root, then he must have a tattoo on his face. (Accompanied by a story in which cassava root is an aphrodisiac, and tattoos are a sign that a man is married.)
• If I give you some potatoes, then you must give me some corn.

In fact, the last of these, which was used in one of the papers that Buller cites, is perfectly consistent with Buller's definition as well. If CT are actually testing the definition of social exchange that they offer, and derived from Trivers, and even use problems that are consistent with Buller's definition, then why does Buller offer this groundless criticism? I have no idea, but even more baffling than that is his second criticism.

Buller's second criticism, which he spends 16 pages describing in reference to several different experimental results, is simple. He points out, correctly, that the logic of an indicative conditional is different from that of a deontic conditional. For an indicative conditional, ~q is the negation of the consequent. However, for deontic conditionals, the equivalent of the "~q" card in the Wason task doesn't actually negate the consequent (such a negation would be something like, "doesn't have to have a tattoo on his face," for the cassava root example above). Instead, it simply says that condition of the rule has not been obtained (e.g., "no tattoo"). So, solving the deontic version of the Wason task involves using a different set of logical principles. Buller argues that this explains the difference in performance in the descriptive and deontic versions (the "content effect,") and CT and their colleagues have never realized this.

Upon concluding these 16 pages, all anyone who is familiar with the literature on social exchange theory can do is say, "Huh?" Cosmides herself noted this in the 1989 paper in which she first described social exchange theory⁸. In fact, a debate has been raging for the last 16 years about whether the content effect can be explained by reference to a mechanism that uses the logical principles of deontic conditionals (Buller's explanation), or whether a cheater-detection mechanism is needed⁹. Sixteen years of debate, and Buller treats the issue like he is the first to notice the problem. In fact, CT believe that they have addressed this issue, by showing that social exchange deontic conditionals produce better performance on the Wason task than non-social exchange deontic conditionals (e.g., in Fiddick, et al. 2000, reference in footnote 7). Since Buller cites this paper, without acknowledging that they address his criticism, I can't believe that he's simply unaware of their answers to it. He doesn't cite, and therefore may not be aware of the neurological evidence that Cosmides and her colleagues have offered to demonstrate that social exchange and non-social exchange deontic conditionals are understood using different brain regions¹⁰. They showed that a patient with brain damage to an area of the brain associated with social reasoning was unable to perform social exchange versions of the Wason task, but performed quite well in non-social exchange deontic versions.

None of this is to say that the Wason tasks actually do provide evidence for the existence of a cheater-detection module. In fact, reasoning researchers and other cognitive scientists have been poking holes in this research for the better part of two decades. Most notably, Sperber and Girroto (e.g., their 2003 paper, cited in footnote 1) note that relevance theory, a theory that states that people use pragmatic cues to search for information that is relevant to their perspective, actually predicts CT's findings, along with another set of Wason task findings that social exchange theory cannot predict. They show that by manipulating perspective and the availability of relevance cues, you can make people perform well or poorly in deontic and descriptive versions of the Wason task. The domain of the problem is irrelevant. Thus, they argue convincingly that the Wason selection task cannot provide evidence for the existence of a cheater-detection module. Sperber and Girroto therefore arrive at the same conclusion that Buller does, but unlike Buller, they do so by actually addressing the claims and research of Cosmides and Tooby.

The neurological data is problematic as well, but Buller doesn't even address it, so readers of his book would be unaware of the problems. They only had an n of 1, which means they were unable to show a double dissociation, and his brain damage was to the medial orbitofrontal cortex and anterior temporal cortex (both bilateral), two regions which are associated with a wide range of social reasoning abilities. Their Wason task is unable to dissociate cheater-detection from general social reasoning, and is therefore not evidence for their theory.

Before I wrap up this review of chapter 4, I should say something about his short discussion of the research on theory of mind. I don't really want to, because I'm genuinely embarrassed for Buller. If he intentionally or unintentionally ignored large portions of the literature on social exchange, he at least made an attempt to look like he was familiar with that literature. In his discussion of theory of mind, however, he makes no such effort. In fact, while there is a huge body of literature, written almost exclusively by non-Evolutionary Psychologists, which demonstrates fairly conclusively that humans have at least some innate theory of mind abilities (i.e., abilities to reason about the thoughts and desires of others), Buller only addresses one finding. He doesn't address the infant gaze-following literature, the language-learning literature, or many of the developmental reasoning tasks showing that from early in infancy, children reason about animate objects differently than they reason about inanimate objects. The finding that he does address, that autistic children tend to perform worse on false belief tasks than non-autistic children, has been criticized extensively already, because the false belief task may not detect theory of mind at all. Buller repeats this, and then argues baselessly that this indicates that there are no innate theory-of-mind mechanisms.

So, if you've read this far, you've probably realized by now that Buller doesn't demolish Evolutionary Psychology. In fact, while he does a very good job of showing just how shoddy EP's shoddiest research, that on mating and parenting, really is, he doesn't even touch EP's strongest research. Of course, even this strongest research has been thoroughly dealt with in the literature. For most cognitive scientists, social exchange theory is either falsified or evidenceless. Even those most willing to accept social exchange theory must admit that the reliance on a single experimental paradigm which has been shown, over the last 30 years, to cause several difficulties in interpretation, is problematic. But one would never know this from Buller's book. All we get, in chapter 4, is baseless criticisms. It might be fair to say that Buller failed to demolish a theory that was already demolished to begin with.

So, while I would definitely recommend this book to the general public, so that they might read the excellent chapters 1-3, and the good chapters 5-7, I wouldn't recommend it to anyone who's interested in the scholarly debate of these issues. I also wouldn't recommend it to economists and legal scholars. While the general public is most interested in what EP has to say about sex, they tend to be interested in what it has to say about social exchange, and since Buller's book is so far off on the social exchange research, it would be worthless to them.

¹Sperber, D. & Girotto, V. (2003). Does the selection task detect cheater-detection? In Fitness, J. & Sterelny, K. (Eds.). From Mating to Mentality. Macquarie Monographs in Cognitive Science, Psychology Press.
²Symons, D. (1992). On the use and misuse of Darwinism in the study of human behavior. In Barkow, J.H., Cosmides, L., and Tooby, J. (eds.), The Adapted Mind: Evolutionary Psychology and the Generation of Culture (pp. 137-159). New York: Oxford University Press.
³Of course, Cosmides and Tooby also tend to treat evidence of a cheater detection module as evidence of massive modularity. However, evidence for one module is not evidence of massive modularity. Buller successfully argues that point when he counters Pinker's analogy to the language module.
⁴ Trivers, R.L. (1971). The evolution of reciprocal altruism. Quarterly Review of Biology, 46, 29-47.
⁵Axelrod, R. & Hamilton, W.D. (1981). The evolution of cooperation. Science, 211, 1390-1396.
⁶Wilkinson, G.S. (1984). Reciprocal food sharing in the vampire bat. Nature, 308, 181-184.
⁷Fiddick, L., Cosmides, L., & Tooby, J. (2000). No interpretation without representation: The role of domain-specific representations and inferences in the Wason selection task. Cognition, 77, 1-79.
⁸Cosmides, L. (1989). The logic of social exchange: Has natural selection shaped how humans reason? Studies with the Wason selection task. Cognition, 31, 187-276.
⁹See e.g., Cheng, P., & Holyoak, K. (1989). On the natural selection of reasoning theories. Cognition, 33, 285-313.
¹⁰Stone, V.E., Cosmides, L., Tooby, J., Kroll, N., & Knight, R.T. (2002). Selective impairment of reasoning about social exchange in a patient with bilateral limbic system damage. Proceedings of the National Academy of Sciences, 99(17), 11531-11536.