UCSD postdoc

Christine Harris and Michael McCullough in the Department of Psychology at the University of California San Diego seek a full-time post-doctoral fellow to help them establish a multi-year program of research on envy. The position comes with two years of funding (including salary and benefits), with the possibility of renewal. In this program of research, we seek insights into (a) the causes of envy, (b) the effects of envy on interpersonal and psychological functioning, and (c) the effectiveness of interventions for helping people reduce their envy. Successful candidates must possess a PhD in psychology, although candidates who have not yet completed their dissertations will receive full consideration. The ideal candidate will possess expertise in the study of emotion (including emotion regulation), personality,  interpersonal relationships, or decision-making. The ideal candidate will also have experience with conducting experiments involving real-time social interaction (in the laboratory or online), and will possess advanced skills in statistics (e.g., structural equation modeling, multi-level modeling), computational models of social decision-making, and preferably both. UC San Diego’s policies regarding post-doctoral fellowships, including details on compensation, can be found here: https://postdoc.ucsd.edu/postdocs/appointment-guidelines.html.
To inquire about the position, please e-mail a cover letter and a CV to Mike McCullough at memccullough@ucsd.edu.

Evolutionary anthropology postdoc at Mannheim

3-Year Postdoctoral Research and Teaching Fellow

Humans possess an unparalleled capacity to learn socially from others with extraordinary fidelity. This capacity has given rise to complex, cumulative culture. And cumulative culture, in turn, has been essential for the success humans have enjoyed in recent evolutionary history. Unsurprisingly, then, social learning receives centre-stage attention in evolutionary anthropology and related evolutionary sciences. Important, but unanswered questions include: What social learning strategies do people employ in everyday life? Moreover, do individuals differ in the social learning strategies they use? And if they do, what explains those differences, both at the proximate and the ultimate level? Does strategy-use, for example, differ as a function of learners’ demographics, their life-history strategies, basic personality traits, the cultural context, or historical/generational trends?

Your tasks include:

  • Collaboration with members of the ERC project on social learning, especially social learning in everyday life via experience sampling methodology (together with Dr. Haun and Dr. Hofmann) and personality differences in the use of social learning strategies (together with Dr. Cenni and Dr. Mesoudi).
  • Teaching seminars (in English or German language) in the area of social and/or personality psychology (broadly defined!). The successful job candidate can chose the topics for teaching themselves. Examples are courses on “social learning,” “cultural evolution,” “sociobiology,”
    “evolutionary social psychology/anthropology,” “(behavioural) genetics ofsocial behaviour,” or “evolutionary genetics of personality.”
  • (Co-)Supervision of theses at the Bachelor’s, Master’s, and PhD level

Your profile:

  • PhD in evolutionary anthropology or related evolutionary sciences, such
    as behavioural ecology, evolutionary biology, or evolutionary psychology.
  • Keen interests in social learning, experience sampling methodology/
    ambulatory assessment, and personality and, ideally, expertise in (some
    of) those areas.

Deadline for applications: April 15th, 2024

Position starts: between Aug 1 to Oct 1, 2024

PDF with full details: http://www.psy.de/evo.pdf

The Ups and Downs of Fieldwork – A Personal “Dispatch From the Field”

– by Nicole Hess

[Communication Officer’s Note: Readers of Evolution & Human Behavior are used to reading the results of fieldwork when the papers get published. However, unless they themselves are field researchers, readers of E&HB may not be as familiar with the *process* of fieldwork and what it’s like to collect such data (I count myself in this category). This blog entry is a personal account of the fieldwork process for one of the papers in the recent special issue on “Dispatches From the Field”. It highlights some of challenges and joys of fieldwork and of adapting protocols from MTurk into the field. Of course, every field site is unique, so anthropologists’ experiences will vary as much do the cultures they study – this is just one illustrative experience. The paper described herein is: Hess, NH, & Hagen, EH (2023). The impact of gossip, reputation, and context on resource transfers among Aka hunter-gatherers, Ngandu horticulturalists, and MTurkers. Evolution and Human Behavior, 44(5), 442-453.]

In the summer of 2012, when our daughters were 2 and 6, my spouse was preparing to head to the Central African Republic (CAR) to continue his fieldwork on recreational drug use by Aka hunter-gatherers. This was his 3rd or 4th trip, and I would be staying home (again) with our young children. I also have a PhD in Anthropology, so as he applied for visas and secured research materials, I wondered if I could join to work with one of the few foraging groups left in the world, the Aka, and revitalize my evolutionary psychological research on gossip as reputational competition. My teaching responsibilities would not be disrupted, because we’d be back just before our university’s fall term started.

We could not take our young children to the field for safety reasons, mainly the high child mortality rate (5 children in the village died during our field season). Inconveniences included limited dietary options and a lack running water or electricity for cooking or personal use. We were fortunate to have reliable grandparents and great-grandparents two states away who were willing to help, and a satellite phone to call twice a week. My matriline agreed to do most of our girls’ caretaking, and my paternal grandparents (who were approaching their 90s) agreed to give them breaks by taking the girls for a day at a time over the month that we would be in Africa.

It is harder to make last-minute changes to fieldwork than lab work due to additional health, governmental, and logistical challenges. We adjusted our travel dates, applied for my visa, and added my name to research permit applications that were about to be processed by the CAR government. I took the risk of getting several vaccines at once so that all the immunities would be in effect by the time we arrived in CAR. We got all that in order, flew to Los Angeles to drop our girls off with my mother, got right back on a plane to Paris for a connecting flight to Bangui (CAR’s capital) for our permits, food, gasoline, and gifts for our hosts such as soap and medicines (aspirin, antiseptics, bandages), and finally drove to our field site; that’s over 48 hours of flights, connections, and driving.

We arrived in the Ngandu village of Bagandou, CAR in late July. The Ngandu are small-scale horticulturalists growing manioc, corn, plantains, and other crops in extensive gardens surrounding the village. They have some market integration, with families producing some cash crops, like coffee for sale outside of the village. Ngandu also trade their crops, money, and small gifts like salt and tobacco with the Aka for net-hunted small game and labor (e.g., Aka work in Ngandu gardens for manioc).

We happened to arrive in Bagandou in the middle of caterpillar season, a short period when most Aka are focused on moving far and wide in the forest to collect caterpillars to use as food. Caterpillars are consuming plant matter prior to metamorphosis into moths and butterflies; they literally rain from the trees as they feast. Caterpillar season had come unusually early this year, so we had to put our primary study, which involved reputation and access to resources, on hold because most adult Aka were not accessible. We decided to run our secondary study first, working with Ngandu participants to replicate an MTurk experiment we’d run earlier.

The MTurk resource allocation experiment involved participants being exposed to stimuli including a vignette with a fictional target individual, followed by several negative vs. positive and relevant vs. irrelevant gossip statements about the target. Participants indicated their opinions of the target, as well as their likelihood of allocating a valuable resource to the target.

The MTurk experiment used stimuli suitable to a WEIRD population. To run it with the Ngandu, we had to create new vignettes, gossip content, and dependent measures that were consistent with Ngandu culture. Initially I created vignettes involving witchcraft, as this is a common precursor to gossip in Ngandu daily life. For example, witchcraft accusations often involve jealousy over accumulations of material wealth. But our Ngandu research assistants quickly vetoed those vignettes, sternly warning us to “never talk about witchcraft” because witchcraft and witchcraft accusations led to serious consequences. They provided several accounts of witchcraft that resulted in painful losses, dangerous behavior, illness, and even death. So we brainstormed for several days with our field assistants, developing vignettes, gossip statements, and dependent measures. The Ngandu value a reputation for generosity, and resource transfers among paternal and maternal relatives are routine. With this in mind, our assistants helped us develop vignettes that reflected common local experiences: inheriting valued items and sharing them with family, and also hiring Aka laborers with whom they often shared gifts like clothing. Our assistants also helped us generate several gossip statements that were to be manipulated. To check the validity of the statements, we recruited dozens of locals to evaluate the negativity and positivity of each statement. So just adapting our stimuli to the local context took an immense amount of work – and we hadn’t even started the actual experiment!

We shared many laughs with our assistants about what kinds of behaviors were associated with “good” and “bad” reputations in our cultures. Some behaviors they viewed as important were not ones we expected; other behaviors that we thought would surely be “good” and “bad” were insignificant to the Ngandu. They told us gripping stories about encounters lions, hippos, crocodiles, and apes; we told them that, where we were from, movies and amusement parks exposed people to such animals as a form of entertainment. They laughed in disbelief at my description of the “Jungle Cruise” ride at Disneyland—and when I convinced them it really existed (with fake animals), and was an experience for which people paid a lot of money, they asked “why would you want to scare a child with this?”.

Once the study was designed, I got to work putting the materials together to present to participants, which was another challenge in the field context. We couldn’t collect data on laptops because of the limited electricity, so I cut uniform 2×6 inch strips of paper out of a flimsy, lined cahier (notebook) from the tiny local market, and neatly hand-wrote our experimental stimuli on them. Then, making good use of my packing tape, I laminated each slip, front and back. The gossip statements written on the slips were to be used hundreds of times in different random combinations for our between-subjects design, so they needed to be sturdy. I made one set in English, and one in French.

Then there was the actual running of the study. We needed translators to present our stimuli to participants who spoke the Ngandu language (diNgandu) or Sango, the main language in CAR. Not all of our research assistants spoke English, so in running our experiment, my spouse/coauthor worked with a translator who spoke diNgandu, Sango, and English, and I worked with one who spoke diNgandu, Sango, and French – some of which I thankfully still remembered from 25 years ago. With the help of our tireless translators, we were able to efficiently run our Ngandu experiment with enough participants to fill our conditions. We found that hearing more positive gossip relative to negative gossip led to a higher likelihood of giving the benefit. And, when gossip content was relevant the context of the competition (family or work), the effect was stronger.

Surprisingly, we still had about a week left before our flight home (only one plane left Bangui for Paris each week, and we could not miss it). We decided to attempt to run our Aka study. By this time, caterpillar season was coming to a close, and the Aka were returning to their camps which were located along trails that radiated from Bagandou into the forest. One of our research assistants who also spoke diAka helped us run this study with adult Aka participants from camps along 2 trails. This study involved non-experimental methods where participants peer-rated one another in response to a small number of questions related to reputation and access to resources (along with age, sex, and relatedness). We investigated the relationships between participants’ peer-rated contributions to their group, reputations, costs imposed on the group, and receipt of benefits from the group. Unlike typical groups of adults in the US, such as co-workers, the Aka in our study had lifelong relationships with each other, and many were biological kin. Aka results showed that contributions to family and community were associated with a good reputation, which in turn was associated with receiving benefits.

Although there were many challenges, this field experience was not just fruitful, but enjoyable. I had been expecting a physically uncomfortable site with hard-to-access participants, where language barriers would limit my ability to study gossip. But the living conditions and climate were pleasant, and language, thanks to our competent and enthusiastic assistants, was no problem at all. Members of the communities were warm, authentic, and willing to share themselves and their cultures with us, and they were curious about what we were up to; this made data collection breezy and gratifying. We wanted to return to CAR soon.

Unfortunately, a few months after these studies, CAR plunged into a civil war that is still ongoing. We get infrequent updates from our research assistants about their lives and the local political climate. Diamonds and gold were discovered in the region around the time we were there, and jobs for men in mining (a dangerous venture that can result in windfalls, but also injuries and death) dramatically increased cash flowing into Bagandou. Beyond disruptions due to civil war and dangerous mining practices, interest from international mining groups in diamonds and gold are increasingly impacting in the region. We have not been able to return in over 10 years.

Read the published paper described in this blog: Hess, NH, & Hagen, EH (2023). The impact of gossip, reputation, and context on resource transfers among Aka hunter-gatherers, Ngandu horticulturalists, and MTurkers. Evolution and Human Behavior, 44(5), 442-453.

crowd of participants in speed-dating

Funny How? Humour as an Evolved Trait

– by Henry Wainwright

Humour is an everyday part of our lives and is present in virtually all human cultures, seemingly both past and present; the oldest known surviving joke being from Bronze Age Sumer, circa 1900 B.C. And while what we find funny is likely culturally and socially influenced, the fact that we all have a sense of humour, irrespective of culture, strongly suggests that humour evolved for some purpose.

One among many evolutionary explanations is that humour may have helped our ancestors to attract a mate. Indeed, individuals today consistently report a preference for humour in a romantic partner. However, it remains unclear why, in an ultimate sense, humour is considered an attractive quality. Humour is enjoyable, of course – but there is nothing inherently enjoyable or attractive about what we describe as funny. The question becomes, why did we evolve to find certain things funny and to be attracted to funny individuals?

The ‘fitness indicator hypothesis’ argues that humour aided ancestral courtship because being funny signals underlying genetic quality. Specifically, the idea is that funniness requires mental performance (e.g. speed, intelligence, creativity), which in turn requires a high-functioning brain, which in turn requires a low load of genetic mutations. Therefore, both being funny and being attracted to funny people are evolutionarily favoured because offspring of these couplings will inherit lower mutation loads and pass on their parents’ genes more effectively.

We tested predictions from the fitness indicator hypothesis by having participants – undergraduate students from the University of Queensland – report their preferences for humour in a romantic partner (i.e. their stated preferences) before engaging in a multiple unscripted, three-minute speed dates with each other, for a total of 860 unique dates. After each date, participants rated their partner on several characteristics including their funniness, their  humour receptivity (they found me funny), and their overall attractiveness.

Audio from these interactions were also surreptitiously recorded for a subset of 563 dates, which enabled the use of an additional, objective measure of humour, in the form of laughter frequency. From there we tested the central predictions of the fitness indicator hypothesis: that funniness and humour receptivity are attractive traits. We were also interested in additional predictions of the hypothesis, namely, that in accordance with parental investment theory, there should be a sex differences in how men and women respond to humour. That is, men should be attracted to humour receptivity in a partner more than women, whereas women, more so than men, should value funniness in a partner.

Indeed, results from stated preferences were largely consistent with these predicted sex differences. However, relying on stated preferences alone is problematic because doing so assumes that participants have sufficient, bias free insight into their own preferences. In practice, stated preferences often fail to predict individuals’ evaluations of potential partners (i.e. their revealed preferences). Therefore, we continued our investigation by looking at revealed preferences using laughter as well as ratings of humour .

We began by looking at how strongly participants’ ratings of their partners’ funniness or humour receptivity correlated with their ratings of the partners’ overall attractiveness. This allowed us to first check the basic premise of the fitness indicator hypothesis: that funniness is actually attractive. Consistent with this premise, partners who were rated as funnier were also rated as having greater overall attractiveness. Notably, the same was not found for humour receptivity – partners rated as more receptive were rated no more or less attractive overall. More damaging for the fitness indicator hypothesis, though, is that the predicted sex differences were not observed at all: the associations of both funniness and humour receptivity with overall attractiveness were similar in men and women.

Using ratings as a sole assessor of revealed preferences can be troublesome, as post-interaction ratings are possibly subject to a halo effect, whereby participants might rate a partner as funnier simply because they were more physically attractive, for instance. Therefore, we examined revealed preferences using laughter as a real-time, behavioural measure of both funniness and humour receptivity. After first establishing that at-partner-laughter (i.e. participant laughter following something their partner said) was positively associated with ratings of funniness, thus partially validating laughter as a measure of humour, we found that neither funniness nor humour receptivity, as measured by laughter, predicted ratings of overall attractiveness. Furthermore, using laughter, we found no evidence that men value humour receptivity in a speed-date partner more than women do, or that women value funniness in a speed-date partner more than men do.

In summary, we found that while stated preferences largely supported the sex differences predicted by the fitness indicator hypothesis, results from revealed preferences, which are taken as more valid than stated preferences, did not support these predicted sex differences and offered only mixed support for the central premise of the hypothesis, that funniness is attractive.

Overall, our results call into question not only the fitness indicator hypothesis, but also (or alternatively) the degree to which parental investment theory can be applied to sex differences in humans’ preferences for fitness indicators. The absence of significant sex differences in revealed preferences alone does not necessarily exclude humour as a fitness indicator; instead, it may be that the degree to which parental investment theory predicts sex differences in human fitness indicators has been overestimated. Humans exhibit mutual mate choice, and as a result, fitness indictors are still expected to evolve, but not necessarily with large (or any) sex differences. So the possibility remains that humour may be a fitness indicator, but men and women differ little, if at all, in their attraction to it. The current study is partially consistent with this possibility, as there is evidence that both funniness was a desirable trait to both sexes similarly. However, further investigation, especially into the role that humour plays in romantic attraction over longer periods of acquaintance, is needed to fully investigate this possibility, as well as to comprehensively test the fitness indicator hypothesis.

Read the original article: Wainwright, H.M., Zhao, A.A.Z., Sidari, M.J., Lee, A.J., Roberts, N., Makras, T., & Zietsch, B.P. (2024). Laughter and ratings of funniness in speed-dating do not support the fitness indicator hypothesis of humour. Evolution and Human Behavior, 45(1), 75-81.

An issue of EHB

New E&HB article format: Short Reports

The official HBES journal, Evolution and Human Behavior, has created a new report format: short reports. Short reports, created in honor of John Tooby, are intended to expedite the publication of concise reports of original research. Short reports contain no more than 3000 words in the introduction, methods, results and discussion combined, an abstract of 200 words or less, and a maximum of 30 references. The introduction, only a few paragraphs in length, should state concisely the evolutionary rationale for the project (for example, the relevant selection pressure/adaptive problem and proposed behavioral/cognitive solution), a very brief description of the methods used, and specific empirical predictions. Short reports may have online-only supplements that contain full materials, supplemental tables, and details of complex methods. However, the supplement may not be used to circumvent the word count. A reviewer/reader of EHB should be able to evaluate the science of a short report solely from the main paper. Members of the Editorial Review Board and Invited Reviewers of short reports will be notified of this new format to ensure appropriate appreciation of its concise nature. Details will appear soon on the EHB website.

ADAPT mentee application

Mentor Application form

THE ADAPT MISSION

Are parents naturally biased towards their sons or daughters, depending on their conditions?

– by Valentin Thouzeau

According to Robert Trivers and Dan Willard’s hypothesis, in many species, parents in good condition should favour male offspring, while parents in poor condition should favour female offspring. Why? First, parents with more resources can support more offspring. Second, in polygynous species, males with more resources are more likely to have many offspring. Natural selection should therefore favour investment in male offspring when parents are in good condition, since their sons will have a chance to have many children in turn. Conversely, natural selection should favour investment in female offspring when parents are in poorer condition, since their daughters have a high chance of having children even if they do not have many resources (see Figure 1 for a schematic representation of this hypothesis). This prediction was tested in a numerous non-human species. For instance, in ungulates, the results showed that when a female’s partner can invest more resources in her offspring, she does indeed produce more sons.

Figure 1 – a) Example of a group in which males with many resources (represented by large circles) are likely to have more offspring than females with many resources, since they can have children with multiple females. b) Representation of the optimal choice in terms of investment by parents in a population represented in a. Parents with few resources should favour their female offspring, while parents with many resources should favour males. c) Prediction of the Trivers-Willard hypothesis arising from the choice in b. The sex ratio of offspring from parents with few resources should favour females, while it should favour males for parents with many resources.

But can this prediction be applied to humans? We often think we are above biology – yet some results seem to contradict this: one study showed that American millionaires have an average of 60% sons and 40% daughters! Does this prediction apply to how we treat our children? In another U.S. study, no difference was found between parents based on socioeconomic status in the amount of time they spend with their sons or daughters. So the results are uncertain.

At present, there are literally hundreds of studies testing the hypothesis in humans, and it is difficult to get a comprehensive view. Also, can we trust the proportion of results that support the Trivers-Willard hypothesis? It may be that researchers were more inclined to publish results that supported the hypothesis rather than those that invalidated it, which may have led to publication bias. We were surprised to find that results from studies involving many groups of animals were synthesised (this is the case, for example, for ungulates and non-human primates), but no synthesis of the work done in the human species had been undertaken until now. This is why we started this work.

We collected 87 studies reporting a total of 821 tests of the Trivers-Willard hypothesis. Although the majority of the samples were based in North America, the geographic coverage was considerable. The analysis of all these studies reveals that the results are largely compatible with the Trivers-Willard hypothesis and that there is no publication bias in this scientific literature that could alone explain the compatibility of the results with this hypothesis.

We then tested whether the hypothesis held true in the birth bias of boys and girls, in the investment bias that boys and girls receive after birth, or in both. We found that tests for both versions are equally prevalent in the scientific literature. However, the results indicate that birth bias is better supported than investment bias. Putting together the last 50 years of research on the Trivers-Willard hypothesis thus allows us to conclude that parents in good condition have, on average, more sons, while parents in poor condition have more daughters.

We have to keep in mind that even if the Trivers-Willard hypothesis is validated for the birth bias, this bias is very small (the correlation coefficient is 0.037). There is simply a very small additional probability of giving birth to sons when conditions are favourable, and to daughters when conditions are less favourable. Nevertheless, these results show how the theory of evolution leads to surprising predictions that allow us to discover unsuspected phenomen.

Read the original paper: Thouzeau, V., Bollée, J., Cristia, A., & Chevallier, C. (2023). Decades of Trivers-Willard research on humans: What conclusions can be drawn? Evolution and Human Behavior, 44(4), 324-331.

The reputational costs of retaliation: Why withdrawing cooperation is better than punishing a non-reciprocator

– by Sakura Arai

Two-person cooperation is ubiquitous in human society. You and your roommate take turns cooking dinner. You water your neighbors’ garden while they are on vacation, and in return, they feed your pet while you are away. But what if your partner fails to return the favor?

Inflicting a cost on those who fail to reciprocate—punishment—is one solution. Think of fines for littering, parking violations, or overdue books. When three or more people cooperate to achieve a common goal and share the resulting benefits (such as clean streets and libraries), punishment does sustain cooperation. But punishing can be counterproductive when two people are trading favors—especially in a biological market where there is competition for good cooperative partners.

Imagine how you could “punish” your partner. You could serve spoiled food to the roommate who keeps “forgetting” to make dinner, or salt your neighbors’ garden when they fail to feed your pet. But would these malicious actions change their mind and encourage them to start reciprocating again? To make matters worse, other people may think that you are a bad cooperator—and vengeful too. They may not want you as a cooperative partner.

There is an alternative to punishing: You can simply withdraw cooperation from your non-reciprocating partner. This communicates the same point—you don’t like the way you were treated. Plus, withdrawing may save your face. It’s possible that their excuses are true and they actually couldn’t return the favor due to injury, mistakes, or bad luck. By conveying the message without directly harming your partner, you may appear forgiving and even considerate.

In group cooperation, withdrawing cooperation has disadvantages that do not exist in two-person cooperation. Withdrawing cooperation from a free rider simultaneously penalizes members of the group who are good contributors. It may also entail abandoning the entire group project and the benefits that come with it. Neither is the case in two-person cooperation, especially when alternative partners are available.

In two-person cooperation, a non-reciprocator can be sanctioned by withdrawing cooperation or by punishing. And your reputation may suffer if you continue to do favors for partners who do not reciprocate. You may appear to be a pushover and easy to take advantage of. Then your partner will certainly keep exploiting you, and so might other people. In terms of reputation, you may be better off sanctioning than just continuing to help.

So, for your reputation, what should you do when your partner fails to reciprocate? We asked over 400 US residents, as a third-party observer, what they would think of someone who took one of the three responses: punish, withdraw cooperation, or neither (keep cooperating).

Here’s a short scenario we presented to participants: Imagine two people, Alex and Casey, interacting with each other through an economic game. There are two roles in this game: giver and receiver. The giver is given $5 and then decides either to share $5 with the receiver or take $5 from the receiver. We told them that Alex and Casey played this game for 3 rounds (without knowing how many rounds there would be). In round 1, Alex was the giver and Casey was the receiver; Alex gave Casey $5. In round 2, Casey became the giver and gave Alex $0. Namely, Alex cooperated with Casey in round 1, but Casey did not reciprocate in round 2.

In round 3, Alex became the giver again. Participants learned that Alex made one of three responses:

  • Punish: Alex took $5 from Casey
  • Withdraw cooperation: Alex gave $0 to Casey
  • No sanction (keep cooperating): Alex gave $5 to Casey.

We then asked participants to rate Alex on 24 adjectives: cooperative, generous, aggressive, vengeful, incompetent, gullible, etc. The goal was to see what reputations (plural intended) they inferred from each response. Did people see Alex as mean and vengeful? How generous and trustworthy did Alex appear? Did she seem gullible or exploitable?

Withdrawing cooperation always had better reputational consequences than punishing. When punishing Casey’s failure to reciprocate, Alex was evaluated as less cooperative—an average of related adjectives such as generous, trustworthy, likable, considerate—and more vengeful—mean, aggressive, unforgiving—than when withdrawing. Moreover, people found the punisher less preferable as a potential cooperation partner than the withdrawer.

What inferences did people make when Alex did not sanction Casey at all?  Participants thought she was highly cooperative and desirable as a partner. But she was also seen as easier to exploit—more exploitable, gullible, incompetent—than when she withdrew cooperation or engaged in restorative punishment (thus recouping her investment in Casey). These two negative sanctions were equally effective ways for Alex to enhance her reputation as difficult to exploit.

Restorative and costly punishment were different, however. In a follow-up study, punishment was costly: To inflict a $5 cost on Casey, Alex had to pay $5. This made her seem as exploitable as the non-sanctioner. Both lost an extra $5: The punisher paid to retaliate and the non-sanctioner paid to keep helping Casey, a partner who took without giving in return. People inferred Alex was easier to take advantage of in both cases, compared to simply withdrawing further cooperation.

A reputation as more difficult to exploit may prevent others from mistreating you. But this reputation can be gained by withdrawing cooperation or restorative punishment: negative sanctions that do not entail extra costs for you. And both kinds of punishment—restorative and costly—produce reputational costs: Compared to withdrawing cooperation, punishing makes you appear more vengeful, less cooperative, and less desirable as a partner. So, in two-person cooperation, withdrawing cooperation may be the best option when your partner fails to return the favor. Our studies show that investigating reputations—multiple aspects of reputation—can shed new light on the functions of motivations to sanction those who don’t give back.

Read the article here: Arai, S., Tooby, J., & Cosmides, L. (2023). Why punish cheaters? Those who withdraw cooperation enjoy better reputations than punishers, but both are viewed as difficult to exploit. Evolution and Human Behavior, 44(1), 50-59.