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09. October 2017 by kurzbanepblog
Categories: Blog, Uncategorized | 1 comment

Leave of Absence

Dear Readers,

It is with sadness that I announce that I will be taking a leave of absence from this blog. I have very much enjoyed the last four years, including and especially reading your comments, but I find myself in need of a break. My hope is to resume after a year or so of leave, and I am working with the staff at Evolutionary Psychology, the online journal that hosts this blog, to find an interim replacement.

Thank you for your ideas, comments, and support over the last four years. Writing for this blog has been a highlight of my recent career, and I look forward to resuming when I can better afford the time at some point in the future.


Rob Kurzban

27. August 2014 by kurzbanepblog
Categories: Blog | 8 comments

Love is a Bridge (Burner)

The BBC reported on some work by Robin Dunbar that finds that people in romantic relationships have two fewer very close friends than people not in such relationships. The simplest – and probably the best – explanation for this is the fundamental zero-sumness of time. (By the way, the Fundamental Zero-Sumness of Time was the name of my Pink Floyd cover band.)Maintaining close relationships requires time, and a new love interest reduces the amount of time one has for non-lover relationship maintenance activities. Single people who try, often with limited success, to get their coupled friend to go out for nights on the town have first-hand experience of this phenomenon.

But if it’s a time constraint, then why do you lose two close friends instead of just one? One could imagine that romantic partners take up as much time as any other close friend.

This reminded me of an idea that I had some time ago, and even did a little work on in collaboration with Alex Shaw (now at the University of Chicago). We presented a poster on the topic back at the Human Behavior and Evolution Society annual conference back in 2009.

The idea takes some of its inspiration from Robert Frank’s classic account of love, which I’ve alluded to about a year and a half ago. (Wowsa. Has it really been that long?) Frank’s account turns on the notion of commitment. Take two potential lovers, equal in all other ways, but one cannot leave the relationship while the other one can. Because all else is equal, the committed one is a better choice; a lover who can’t leave means no risk of the loss of investment in the partner. In turn, this means that potential lovers gain an advantage by signaling that they can’t leave. If I can reliably demonstrate my inability to switch mates, then I become a better choice for you, again all else being equal.

Frank thinks that the emotion of love serves this function. For Frank, love entails irrational attachment to the individual who is loved, along with appropriate emotional expressions and behavior that conveys these feelings.

I have always worried about this answer because it seems to be susceptible to love mimics. What prevents people from signaling irrational ardor, but then leaving when another, better option presents itself?

This led to the Love as Burning Bridges idea. (I want to say up front that I don’t necessarily think that this is a good idea. Just that it’s an idea.)

Suppose that it’s true that people are better off when they have a larger, rather than smaller, group of close friends. This seems plausible from the perspective of various theories of what (human) friends are for. If, for instance, they are useful for reciprocal exchange, having more rather than fewer provides more chances for mutually beneficial transactions. If friends are used as allies, for support when conflicts arise, then, again, more is better than fewer.

Suppose further that as the size of your close friendship network gets smaller, each additional loss of a close friend is even more costly. Losing a friend when you have many isn’t a big deal; losing one when you have only one is a very big deal. All of this is in service of the argument that one way to convince a romantic partner that you aren’t likely to leave is to make the cost of leaving that much higher. One way to do this is to reduce the size of one’s close circle of friends. This puts all of one’s eggs, as in were, in one basket. A lover occupying one of six close friendship slots isn’t as costly to lose as a lover occupying one of four slots.

So, could it be that adding a lover doesn’t reduce the number of close friends one maintains simply as a side-effect of spending time with them? Could it be that part of the design of the emotion of love is to neglect one’s inner circle of friends, to convey that one’s partner is such a crucial part of one’s social circle that leaving them would be very costly?

As I intimated above, I don’t have a tremendous amount of confidence in this idea. With Alex Shaw – did I mention he’s now at the University of Chicago? – we ran a priming study. Here is part of the abstract:

… in order to get the benefits from this putative commitment device, love must be honestly signaled. If love caused individuals to spend less time with friends, this would impart a cost on the person in love and could potentially act as an honest signal of commitment. To test this idea, we assigned subjects to receive either a Love or Normal day (control) prime. Subjects also then filled out a questionnaire that asked them how likely it was that they would spend time with friends, take a nap, surf the internet, or do school work after the experiment. We found that individuals in the love prime reported being less likely to spend time with friends after the experiment than individuals in the control prime condition, but that these primes did not influence the likelihood of doing other activities.

These results do not, of course, settle the issue. Having said that, the data described by the BBC report seem interesting in this context, and the smaller number of close friends for those in romantic relationship is exactly the pattern that the Bridge Burning proposal predicts. Having said that, it’s not clear to me the best way to go about putting the Bridge Building model to the test. Maybe a reader will give this some thought, and have some ideas to share at the meeting of the Human Behavior and Evolution Society in Natal, Brazil at the end of the month…


Shaw, A., & Kurzban, R. (2009, June). Love as Burning Bridges. Poster Presented at the Human Behavior and Evolution Society Conference, Fullerton, CA.

08. July 2014 by kurzbanepblog
Categories: Blog | 2 comments


I’ve puzzled for some time about why people flirt. Students of (non-human animal) behavior know that males of many species aren’t typically subtle about signaling their interest in mating. A peacock displaying his tail feathers to a peahen is more or less saying, “My quality is this high, and I’m telling you this because I’d like to mate with you.” The males of other species sing, dance, strut, and generally make a big show to indicate their quality and their interest.

Set against this backdrop, humans seem, in a word, weird. People do signal to potential mates in various ways, displaying wealth and skills and so on, mirroring animal signals of quality. But at least some elements of human mating carry a certain ambiguity, especially regarding one’s intentions. “Do you want to visit the chili cook-off?” might reflect an intention for a casual, Platonic chat and a nice, hot bowl of chili. Or it might not.

As I say, I’ve puzzled over this for some time. So much so that from time to time I’ve conducted some field research on the subject, which led me to the conclusion that one important reason that people indicate their potential sexual intentions in a subtle way is that abandoning subtlety leads to drinks in one’s face, which in turn results in an unpleasant stinging sensation in the eyes. These informal investigations focused my attention on the issue of costs.

What are the costs of peacock-like signaling of sexual intent? In 2007, I had a talented group of undergraduates conduct a little study inspired by what we self-satisfyingly called the GIST model, standing for the Gradual Increase in Sexual Tension. One part of this model was the idea was that perhaps the costs of flirting had to do with third parties; if so, flirting should be more subtle when pairs were being observed. So, we had subjects chat with an opposite-sex partner in a chat room, either with or without a third party observer able to see the chat session. We got some small effects of this treatment – a bit more restraint when pairs believed (correctly) their chat session was being observed by another subjects – and a few additional undergraduate projects followed, many of which had similarly clever abbreviations and similarly small effects.

All of which leads me to a new paper (“Covert Sexual Signaling: Human Flirtation and Implications for Other Social Species”) that came out last week by Andrew Gersick and me in which we try to address this issue. Gersick is a student of the famous animal behavior scholars Robert Seyfarth and Dorothy Cheney, and has done some work showing that cowbirds sing songs of different “strength” depending on the social context.

A key part of the idea is that in various species, third party observers interfere with others’ mating attempts. This is unsurprising; male-male competition is more or less all about interfering with others’ mating attempts. Could this be driving the human subtlety of signaling one’s sexual intentions?

Perhaps. But as the drink-in-face example illustrates, there could be potential costs even if no one else is watching. For instance, in the context of a Platonic opposite-sex relationship, a (relatively explicit) signal of sexual interest might damage the relationship. Everyday experience – and When Harry Met Sally – suggests that an unmistakable sexual proposition in a previously non-sexual relationship tarnishes the relationship. In contrast, a subtle signal of potential sexual interest, if gently brushed aside, leaves both parties able to maintain the fiction that the interest was never signaled in the first place.

If explicit signals of sexual interest carry potential costs, either from the receiver or third parties, then less explicit signals might reduce or eliminate these costs. That raises the problem of how to indicate interest. One way to do this is to indicate interest in such a way that observers might not be able to infer with certainty that one’s intentions are, in fact, sexual. Ideally, one wants to signal in such a way that a receiver can detect that there might be sexual interest but in a way that is plausibly deniable.

One way to use this is to use “indirect speech.” When I ask if you want to go to the chili cook-off, there are (at least) two different questions I might be asking you. The surface meaning is whether or not you want to get some chili. A second meaning is a question about whether you’re interested in a date, a prelude to mating. If you are not the least bit interested in a date, you can interpret my remark as a simple invitation to chili, and indicate that you don’t like spicy food, or what have you. Further, if you challenge me by indicating that you’re engaged and so really shouldn’t be going to chili cook-offs, then I can innocently say that I was just being sociable, as opposed to making anything resembling a sexual overture. Indirect speech, and other ambiguous moves in social dynamics, allow parties to test the waters for interest while simultaneously minimizing potential costs imposed by the target or observers by leaving a safety valve of deniability.

We add one additional element, and by “we” I mean this piece was all Andy’s idea. Suppose it’s true that to be a “good” flirt, one has to be appropriately ambiguous. Considerably greater subtlety is required when one is trying to signal sexual interest, say, in front of a potential mate’s partner than in a context in which a pair is alone, with previously indicated mutual attraction. Using an appropriate level of overtness, then, itself becomes a kind of a metric of skill, and something on which potential mates are evaluated.

At the end of the paper, we identify a number of predictions for both sender and receivers of flirtation. Flirting is, in my experience, a difficult phenomenon to study, but I hope that this paper will stimulate additional work in this relatively sparse research area. If anyone out there wants to collaborate on some work testing these ideas, I’d be happy to discuss them. There’s this great chili cook-off we could go to…


12. June 2014 by kurzbanepblog
Categories: Blog | 5 comments

Trigger Warnings in Classrooms

I had a unique experience teaching my Evolutionary Psychology class this semester, and see, from a recent article in the New York Times that I am not alone.

[Note: the following post discusses “trigger warnings,” and, therefore, refers to topics that some might find unpleasant to read about.]

The above warning is, more or less, the issue. As the Times reports, campuses across the country are increasingly discussing the question of whether faculty members should warn students ahead of time if topics that might evoke unpleasant feelings might be discussed in class. People who have been traumatized, for example, might find it difficult to hear discussions or depictions of an event similar to the one which they have been involved.

My interest comes from having gotten feedback from my teaching assistants – so my experience, I should be clear, is second hand – that two students in my class were upset that I did not warn them about the content of the class, which included a discussion of research and data on sexual coercion and rape. I gave a presentation not unlike the one that I gave last year, discussing the adaptation/byproduct debate surrounding sexual coercion, and some of the data on victims, about which I wrote a little post.

I was surprised to get the complaints, if for no other reason than I had briefly discussed sexual coercion in the prior lecture, and the one that elicited the complaints was more or less continuing that discussion, which made me feel that students might have been able to predict what I would be talking about.

Another connection for me is that the institution where I received my PhD, the University of California Santa Barbara, has recently been in the news cycle on this issue. Back in February, the student senate asked the university to require warnings from professors when they plan to discuss material that might trigger symptoms of PTSD.

From the two articles that I read, it seems to me that there is actually more than just a single issue here, the question of warnings. In particular, the report in the Daily Nexus, the student paper, includes the point that the senate also wants professors to “refrain from docking points from those who opt out of attending class that day.” Another source indicates that the resolution states that “students who feel they may have a negative emotional response to such content, including distressing flashbacks or memories, should be allowed to leave the classroom or skip class altogether without being penalized.”

The first quote makes it sound like professors are being asked not to penalize people on the basis of attendance. The latter quote makes it sound like the professors are being asked to allow students not to be responsible for learning the material in question.

I myself am unsure where I stand on all of these issues, but it seems to me that this is a topic that might be relevant to people who teach evolutionary approaches to behavior, which includes topics that might be on the list of potentially triggering topics, including rape, intergroup aggression and violence, and so on.

The Times article lays out the arguments from various angles. On the one hand, it seems reasonable to try to minimize unnecessary trauma to those who have experienced unpleasant prior events. It seems to me that the question is how the weight of that concern compares to the arguments on the other side.

I myself don’t feel that it infringes on my academic freedom to tell students in advance what I’m going to discuss. My syllabus is, I admit, a bit sparse, especially compared to others I’ve seen. The week I discussed sexual coercion – in addition to other topics – is listed as “Mating Strategies.” This is, to be sure, vague. I’m not sure I would feel terribly put out to be asked, or even required, to indicate when I was going to discuss various topics, as long as the topics that I had to announce were sufficiently well specified that I could comply without too much trouble.

Of course, I would be a lot less sanguine about being asked to forgo covering material in my class because some people might find it disturbing or offensive. My sense isn’t that this is likely to happen at Penn or elsewhere any time soon. But I think that the risk of some harm to students is outweighed by the potential pedagogical loss of not being able to address particular topics at the behest of an administration. As I say, I don’t think this is yet a serious issue.

To me, however, there is a potentially genuine issue arising from those two quotations above that go beyond the question of warnings. Should be excused from class, and, further, excused from responsibility to learn the material?

I haven’t taken a firm stance on this, but I think I would oppose such policies. In essence, one aspect of the tradeoff seems to be the amount of discomfort saved by excusing such students set against the amount of harm done by excusing them from learning the material. Instructors wouldn’t, more or less, put material in their courses if they didn’t think there was value in learning it. Excusing students, then, undermines the pedagogical mission, which it seems to me ought to be given a great deal of weight. There could, I suppose, arise issues of equity. Are the students not so excused unfairly burdened with having to learn more material? Should there, then, be a some sort of test to qualify for being excused?

As I say, I think this issue might arise for members of the evolutionary psychology community because of the nature of the material that we teach, which includes – among many other topics of course – sex and violence. I would be interested to hear – offline or not – others’ experiences with this issue. My suspicion is that this issue will get increased attention in the near term, and those of us who teach classes might take this moment to reflect on our own views on the topic.

20. May 2014 by kurzbanepblog
Categories: Blog | 4 comments

Angry (Hungry) Birds

Note: This blog post is a joint Fatima Aboul-Seoud/Rob Kurzban production.

For some reason, I recently was interested in the relationship between food and aggression, and so I had a look at an old paper published in 2000 entitled “Effects of short-term hunger and competitive asymmetry on facultative aggression in nestling black guillemots Cepphus grylle.” In the research reported in this paper, the authors, Cook et al. were interested in something called the “food amount hypothesis.” Suppose that two siblings are being provisioned by parents. When times are good, inclusive fitness implies that the chicks will be, more or less, cooperative. When times are tough, however, the logic of parent/offspring conflict kicks in because the marginal benefit of food to me is now greater, so relationships between even full siblings might turn violent. As they put it, the prediction is that “dominant siblings become more aggressive during periods of food shortage, thereby obtaining a disproportionate share of total available parental resources.”

The happy couple.

The happy couple.

Black guillemots (pronounced: berdz) are a convenient model species because eggs are laid in pairs over a period of a few days. The authors set out to determine if the amount of food delivered was a proximate cue for sibling aggression. To do this, they recorded videos of 20 broods (5 in the control group and 15 in the experimental group). In both groups, they began observation before the eggs were laid and recorded when each egg was laid and hatched. The first chick to hatch was marked and called the A-chick, and the second chick to hatch was called the B-chick.

The experiment looked at what would happen if parents were prevented from feeding their chicks. The experimental manipulation, which is sort of awesome, is described this way: “[P]arental provisioning was prevented… by placing an adult scaring device—either balloons with painted eyes or a fiberglass great black-backed gull—near the entrance of the nest and in view of the returning adult.” So, for six hours out of a twelve hour observing cycle, parents were scared away from feeding their chicks.

Figure 1. Attacks by condition, over time.

Figure 1. Attacks by condition, over time.

In the control group, chicks were generally non-aggressive. (See Figure 1, from the original manuscript.)  In the experimental group, during period 1 (before the scaring device was introduced), rates of attacks between experimental groups and controls didn’t differ. Aggression rates were higher during period 2 (when the scaring device was present) and highest during period 3 (just after the device was removed).  The researchers also measured provisioning and, indicating the utility of aggression, after the deprivation phase of the study, A-chicks got a relatively larger fraction of feeds from parents relative to controls. The authors conclude (p. 285)”

A-chick aggression in black guillemot broods was elevated only after parental provisioning rates were experimentally reduced. When parental provisioning resumed, adults did not adjust their feeding rate in response to changes in their offsprings’ requirements, and the consequence of the intersibling aggression was a skew in the distribution of food received by siblings in favor of the dominant A-chick.

So, in summary, in these organisms, it appears that having less food causes increased aggression, even in the context of what would otherwise be a close, even cooperative, relationship. These results illustrate that aggression is deployed conditionally, in a principled way, depending on context.

Note that these results do not illustrate, at the risk of repeating myself, that chicks require parental provisioning in order to have the fuel necessary to muster the willpower not to harm their siblings. That would be an obviously silly way to understand these results. Right?

Anyway, part of the reason I looked at this paper was that I recently saw a talk by Johannes Haushofer, who ran studies investigating the effects of direct transfers of money to very poor households in Africa. Very generally, poor households endowed with more resources (compared to controls not so endowed) had (a little) better food security – because additional funds were used to buy food – and, in addition, domestic violence against women went down, as reported in a summary of the work. These results suggest (but of course can’t causally establish) that having less food leads to more aggression in the context what would otherwise be a close, even cooperative, relationship.

Oh, and, speaking of humans, and in completely unrelated other news, the Economist and other news outlets are reporting on a new paper in Proceedings of the National Academy of Sciences that shows a relationship between having less food and increased aggression in the context of what would otherwise be a close, cooperative relationship, the theme illustrated so well by the international “You’re Not You When You’re Hungry” Snickers ads, such as this one.


Cook, M. I., Monaghan, P., & Burns, M. D. (2000). Effects of short-term hunger and competitive asymmetry on facultative aggression in nestling black guillemots Cepphus grylle. Behavioral Ecology, 11(3), 282-287.

15. April 2014 by kurzbanepblog
Categories: Blog | 7 comments

Another Tool for Inferring Function: Maps

In The Heretic in Darwin’s Court, Ross Slotten describes the debate between Darwin and Wallace about the function of zebra’s stripes:

The zebra’s stripes, which Darwin regarded as useless on the open African plains, alerted a straggler to the location of the herd or camouflaged the animal when foraging or resting in the bush. ‘Until the habits of the zebra have been observed with special reference to these points,’ Wallace wrote, ‘it is surely somewhat hasty to declare that stripes ‘cannot afford any protection’”

A new paper, covered in a number of media outlets, vindicates Wallace’s proposal, but the protection is of a different sort from what he had in mind.

Caro et al., in a paper entitled “The function of zebra stripes,” suggest that the zebra stripes are not for protection against large predators, but rather against small ones: insects.

The paper has been covered by any number of media outlets – you know that a story is not news anymore when even Saturday Night Live Weekend Update picks it up (5:08) — so I’ll just comment on one aspect of the work that fits with a theme that I’ve possibly mentioned once or twice before on the pages of this blog, the nature of evidence of function.

A few years ago, for example, I wrote about horses of the sea variety, discussing work that used models of seahorse shapes to infer that the function of their distinctive heads had to do with increasing the range at which they could catch prey. The idea, which I think is an important one, is about the epistemological question of what sorts of evidence can be used to infer the function of a trait, whether physical or behavioral.

This issue arises in evolutionary psychology because Various Critics think to teach us in the field about what sorts of evidence biologists use when they make claims about function. This often has to do with genetics, heritability, phylogeny, and so forth. The point of the seahorse post was to say that while of course other sources of evidence are relevant to the question of inferring function, evidence from computer models also bear on the question. The key is finding or creating data that speak to the design features of the trait from the standpoint of the putative function.

The reason that I like the paper about zebra’s stripes is the evidence that it brings to bear in the service of the aggressive claim in the title of the paper, the function of zebra stripes. The authors reasoned as follows. Suppose zebra stripes, as Wallace seems to have thought, afford protection against large predators, such as hyenas, lions, and tigers. If so, then species that live in places with higher densities of these predators ought to be more likely to have stripes than closely related species who live in places with lower densities of these predators. Similarly, if stripes defend against insects, then species that inhabit regions with more of the insects that prey on zebras should be more likely to have stripes than species that inhabit regions with lower densities of these insects.

Where the zebras are.

Where the zebras are.

To look at this, the authors used maps, measuring the overlap between striped zebras compared to their non-striped relatives and the distribution of predators of the large (hyenas, etc.) and small (insect) variety. (See the accompanying figure.) In part, their results were that “the presence of body stripes was very strongly associated with presence of tsetse flies.” At the end of the first paragraph of the paper, the authors write: “A solution to the riddle of zebra stripes, discussed by Wallace and Darwin, is at hand.” Stripes are for protection form insects.

If that’s the function, what’s the mechanism? It seems to have to do with the perceptual apparatus of the flies. The alternating pattern of black and white might confuse the insects’ system sufficiently to reduce their ability to land on the zebras. Previous work showed that the distinctive zebra striping pattern attracted fewer houseflies (tabnids) by virtue of the fact that “the light and dark stripes of a zebra’s coat reflect very different polarizations of light in a way that disrupts the attractiveness to tabanids” and, further, that “the stripe widths of zebra coats fall in a range where the striped pattern is most disruptive to tabanids.”

07. April 2014 by kurzbanepblog
Categories: Blog | 1 comment

Excess Success – Research Practices in Psychology

A new paper adds to the continuing discussion of research practices in psychology. The paper (citation below), in press at Psychonomic Bulletin and Review by Gregory Francis, analyzes the last several years of published papers in Psychological Science, a premier outlet in psychology, and in essence asks if there is “too much success” in the reported studies.

The analysis uses the “test for excess significance” (TES) (Ioannidis & Trikalinos, 2007). The intuition is that if you run a number of experiments – N –  measuring an effect of a certain size, then it is possible to compute how likely getting N rejections of the null is for all N experiments. So, if the odds of getting an effect are, say, one in three, given the power to find the effect, then the chances of getting two such effects is the product of this probability, or one in nine. If one finds more successful rejections of the null than one would expect, given the power to reject the null, this suggests that something is amiss. From the analysis alone one can’t say where the excess success comes from, only that there is a bias in favor of positive results. According to Francis, the cutoff for the value of the TES is 0.1. As he puts it: “A power probability below this criterion suggests that the experiment set should be considered biased, and the results and conclusions are treated with skepticism.”

He ran the TES on published papers in Psychological Science between the years 2009 and 2012 (inclusive) that reported four studies or more – the minimum number for the TES analysis – and found that 82% of the 44 paper that met the inclusion criteria had values less than the cutoff value, suggesting a substantial degree of “excess success” in the journal.

I’m confident that the paper will stimulate a great deal of discussion. My interest for the remainder of this post is in a possible pattern in the TES data. When I first read the paper, my eye was caught (slightly ironically) by the short title of one of the papers investigated, The Wolfpack Effect, by my friend Brian Scholl and colleagues, which I wrote a little post about around the time it came out. This paper was one of the eight that surpassed the .1 threshold.

I looked a bit more closely into some of the others that similarly had TES values above .1. The largest TES value, .426, was also in the area of perception, looking at how people can quickly assign stimuli to categories (e.g., “animal”). The next largest TES value, .348, was another perceptual study, having to do with the way that objects are represented in the visual system. Two other papers had to do with, first, another effect in vision – how the color of light affects visual processing of fear-inducing stimuli – and, second, an effect in audition.

So five of the eight successes, as indexed by TES, are from the field of perception. The other three were not, having to do with predictors of subjective well-being, reducing prejudice, and appreciation of others’ help. One paper in the area of perception – about visual rivalry – didn’t fare as well. Neither did a paper looking at the possibility that people see objects they want as being closer to them.

So perception didn’t run the table, but, still, without looking very closely at all the papers in question, it seemed to me that the low-to-medium level perception work distinguished itself in the analyses. (I might add that another paper I posted about, didn’t do as well as the Scholl work.) The balance of the papers covered a fairly wide range of topics. To take just two to illustrate, one paper (TES = .041) presented six studies that purported to show that “[h]andling money (compared with handling paper) reduced distress over social exclusion and diminished the physical pain of immersion in hot water.” A second paper (TES = .036) purported to show that when “religious themes were made implicitly salient, people exercised greater self-control, which, in turn, augmented their ability to make decisions in a number of behavioral domains that are theoretically relevant to both major religions and humans’ evolutionary success.”

In any case, from the results that Francis reports, I don’t think any strong inferences can be drawn. To my eye, it looks like perceptual work does better than the other areas, but more systematic work will need to be done.

It seems to me that it’s worth knowing if some subfields score better in this respect because it speaks to the explanation for the problems. As Francis puts it: “Unless there is a flaw in the TES analysis…there are two broad explanations for how there could be such a high rate of apparent bias among the articles in Psychological Science: malfeasance or ignorance.” It doesn’t seem to me that there’s any reason to think that people in perception are any more ethical than people in other areas. If that’s true – though of course it might not be – then the place to look for the source of the problem is not in malfeasance.

Are there other candidate explanations? Could there be fewer opportunities for researcher degrees of freedom in perception? Could it have to do with the nature of theories in perception, compared to other areas?

I’m not really sure. But it could be that finding patterns in different areas of psychology might be useful for determining the sorts of best practices that will ameliorate these sorts of issues. My guess is that this paper will stimulate many profitable conversations.


Francis, G. (in press). The frequency of excess success for articles in Psychological Science. Psychonomic Bulletin and Review.

Ioannidis, J. P. A., & Trikalinos T. A. (2007). An exploratory test for an excess of significant findings. Clinical Trials, 4, 245-253.

06. March 2014 by kurzbanepblog
Categories: Blog | 9 comments

Why Are Gorillas So Strong If They Don’t Go to the Gym?

Who says gorillas don't know squat?

Who says gorillas don’t know squat?

Let me start by saying that I don’t actually know much about the topic I’m writing about today and, in a tiny, personal celebration of blissful ignorance, I decided not to try to learn much about the topic I’m writing about before setting pen to paper. I sort of think of this post as a cry for help, so if anyone wants to tell me gently (to spare my feelings), offline (to spare my reputation) what I should  have read before trying to write about this, please drop me a line.

Ok, here’s the thing. Human muscles seem to atrophy with disuse, as anyone will tell you who has had to take a six week hiatus from the gym because of a bunch of gorram injuries. Muscles are a bit like foreign languages and health flexible spending accounts: use it or lose it.

My sense is that many people think that this is a general property of muscles. Or, at least, my sense is that people think that in order for muscles to get big and stay that way, they need to be used.

Don’t get me wrong. I think that’s true of (some, most, all?) human muscle tissue. But just because it’s true for humans, I don’t think that it’s true for other critters, and I don’t think that it had to be true for human muscles, whatever that “had to” might mean.

Part of the reason I was thinking about this is because of the self-control literature I’ve been subjecting myself to, in which people say that self-control is “like a muscle.” In that word “like,” self control researchers seem to have in mind, first, that self control is “like” a muscle in that muscles get tired with use over the short term and, second, that muscles get stronger with use over the long term.

Now, the first part probably has to do with the way that muscles work. Muscles turn chemical energy into mechanical energy. This is accomplished through mysterious processes going on in the cells, and the little power plants that do the work run out of fuel, produce metabolic byproducts, and heat up, some or all of which reduce their ability to produce mechanical energy, which is why each rep is harder than the last one. There are, then, physiological constraints that tissues face over time. This reduction in output is, in short, a necessary side effect.

What about the second bit, the idea that muscles get stronger with use over longer time scales? Or, in the same vein, why do human muscles seem to get weaker over the long term if you don’t use them.

Which brings me to gorillas. I don’t know about you, but I’ve spent a fair bit of time watching gorillas in zoos, not to mention Gorillas in the Mist, and they strike me as, in a word, lazy. Juvenile gorillas do seem to frolic a bit in the enclosure, but adult males seem to punctuate their bouts of sitting around munching on foliage with short intervals of sitting around not munching on foliage. Ok, sure, in the wild, right, every now and then two male gorillas will get into a fight, and I’m sure that provides a robust work out. And of course in zoos, no such battles occur because no zoo would put potential rivals in the same enclosure, and risk the loss of a precious gorilla.

Lazy zoo gorillas, then, don’t seem to get much of a workout, but those dudes are huge.

So, from my completely informal observations that gorillas in zoos are A) lazy and B) buff, I infer that there’s nothing intrinsic about (gorilla) muscles that requires that they atrophy with disuse.

If human muscles atrophy if unused, but gorilla muscles don’t, then it seems that some sort of explanation is required.

My guess is that the relationship between how much you use a muscle and how big it gets is a design feature, not a byproduct, and this relationship varies across species.

For gorillas, my guess is that no matter what sort of life you’re leading, you might need your muscles at any given moment. In the case of males, this is either to defend the harem against rivals, or, on the other side, fight to take over a harem. If such attacks might occur at any time, then muscles must be kept robust more or less continuously, independent of whether you’re working out regularly. As with everything else, there’s a tradeoff, and the metabolic cost of maintaining the muscles is a good investment insofar as the defenses must always be manned.

Maybe something different is going on with humans. People are unusual in many ways. In How the Mind Works, Steve Pinker quotes Ambrose Bierce’s Devil’s Dictionary, which defines humans thusly:

Man, n. An animal so lost in rapturous contemplation of what he thinks he is as to overlook what he indubitably ought to be. His chief occupation is extermination of other animals and his own species, which, however, multiplies with such insistent rapidity as to infest the whole habitable earth and Canada.

That last part is relevant to the present point. People live and probably have lived in tremendously different ecologies. The ecology probably influences which muscles are worth paying the metabolic cost to maintain. Are you doing a lot of persistence hunting? Probably you want to invest in big leg muscles. Paddling a kayak? Best to have big upper body muscles.

And of course the best way for the system to know which muscles are worth investing in are the one that are being used. So, a good design feature is to build up muscles for tomorrow that you’ve been using a lot today. Other muscles, by virtue of the fact that you’re not using them, aren’t worth the cost. So, unused muscles are hung out to dry.

26. February 2014 by kurzbanepblog
Categories: Blog | 9 comments

What Are Social Psychologists Talking About in 2014?

Some members of the Buss tree, at SPSP 2014

Some members of the Buss tree, at SPSP 2014

The Fifteenth Annual Meeting of the Society for Personality and Social Psychology was held this past weekend in Austin, Texas. I was able to attend the event, and managed to go to nearly as many sessions as I did last year, though I missed last year’s total by one. On the flip side, I was able to make excellent use of my time, rekindling old relationships with friends and colleagues and developing some new ones.

The highlight for me was, perhaps unsurprisingly, the evolutionary psychology preconference, sponsored by the Evolution and Human Behavior Society. (I myself was speaking at a different preconference, so did not make the entirety of the event. Still, I managed to sneak away for a while in order to attend some talks.) David Buss gave a thoroughly engaging presentation, as usual, as did his intellectual descendant, Martie Haselton, who showed some very interesting new results relevant to the recent debate regarding the ovulatory cycle results. Very generally the nodes of Buss’ tree were well represented. His students and his students’ students continue to make their respective marks on the field. A nice feature of the preconference is that only one talk takes place at a time; there are no parallel sessions. Conferences such as HBES, in contrast, require one to choose where one is going to direct one’s attention, and I’m grateful that I didn’t face that particular problem at SPSP. (See picture above for a group shot.) Jessica Li and Stephanie Cantú did an excellent job organizing, and I for one am very grateful for the work they did on the preconference, though still very uncertain about the diacritical mark on Stephanie’s name.

Moving to SPSP proper, as I have done in the last two years, I analyzed the content of the SPSP program to get a sense – as I always say, an imperfect one – of what topics have the attention of researchers in social psychology. I couldn’t find a .pdf of the program online, so the text had to be scraped off of the relevant web page, which could have introduced some errors. (The passive voice in the previous sentence is meant to imply that I didn’t do the work of scraping the text myself. Hat tip to Fatima Aboul-Seoud for doing this).

As in the past, holding aside articles, conjunctions, and words such as “session” and “poster,” social (1196) is, unsurprisingly, among the top finishers. “Personality,” the other P in the name of the Society, had only 397 mentions, and I wonder if they should consider reversing the order of the p-words in the name of the organization. This year “self” (1358) was the most frequent substantive word. As I’ve pointed out previously, this is in no small part due to the fact that the word is used in so many different constructions, both as an adjective – self-esteem, self-regulation and (I’m not making this up), self-transcendence – and as a noun, as in “High status identity concealment alleviates threats to the self” and “the concept of the self is like a blow-up sex doll: easy to use but ultimately devoid of meaning.”

It was an excellent conference for relationships. The singular, relationship, came in at 566, with the plural not far behind at 450. Attitudes (413) fared well, and again positive (387) edged out negative (365), and individuals (378) lost out to people (408) – but not group (350) – observations that I’m sure contain some deep wisdom about the human condition.

Once again prejudice (346) was a popular topic, with identity (341) not far behind. Stereotyping (225), the gerund, wasn’t as popular, but if you combine it with stereotypes (99) and stereotype (90), then you can see that really this topic is faring quite well. Back up in the 300s were women (313) and gender (315)

Moral (300) and morality (121) once again put on a strong showing. Emotion (362) and emotional (219) beat the heck out of cognition (41), to say nothing of metacognition (2).

Here is a partial list of words between 300 and 200:

300 role
300 moral
298 perceived
279 health
250 perceptions
243 motivation
237 related
234 perception
230 person
227 goals
225 stereotyping
220 traits
219 emotional
218 esteem
217 men
216 individual
216 associated
210 groups
210 affect
206 bias
201 performance
201 intergroup

And between 200 and 100, here’s a sample:

152 regulation
146 attachment
145 romantic
144 judgments
138 lower
137 judgment
135 relations
134 culture
131 psychology
130 cultural
128 political
121 morality
121 ingroup
121 anxiety
119 racial
117 rejection
117 race
116 stress
116 interpersonal
113 persuasion
112 sex
112 norms
110 orientation
108 risk
107 consequences
106 religious
103 partners

How is evolution doing at SPSP? In my 2012 post, I wrote that “evolution-related terms (evolutionary, evolved, evolution, evolutionary) came in at 30, 15, 11, and 4.” In 2013, I wrote that “evol* comes in at 47 – evolutionary (25), evolution (17), evolutionarily (5).” This year, evolution (32) and evolutionary (16) once again posted meager showings. Evolved (4), evolve (1) and evolutionarily (1) bring the evol* total to 54, between 2012 and 2013. Evolution was again less frequently discussed than facebook (89), and we didn’t do as well as mindfulness (64). (Facebook is on the rise, appearing 51 times in 2012, and 82 times last year.) A substantial number of appearances of “evolution” were in the heading of a Poster Session (Poster Session D-Evolution). One poster suggested that: “It is commonly assumed that sex and violence sell, but evolutionary theory predicts the opposite,” a prediction that I confess surprised me, but I didn’t see the poster. Jeff Simpson chaired a symposium “Lust in our Ancestral Dust: Evolution, Attraction, and Relationships,” accounting for a number of other instances of evolution-related words.

A few people have asked me if social psychologists are still working on glucose as the self-control resource. I always give the same answer, which is that I don’t know. This year’s program implies that they if they are, it’s minimal. While one poster asserts that “Research has shown that ego-depletion is promoted by stress and prevented by higher glucose level,” the word itself appears only three times.

19. February 2014 by kurzbanepblog
Categories: Blog | 2 comments

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