Botox for crow feet wrinkles: Smiles were rated as being happier, more felt, more spontaneous, & more intense than those posed by the same patients under the same conditions & instructions in post-treatment photographs

A Novel Test of the Duchenne Marker: Smiles After Botulinum Toxin Treatment for Crow’s Feet Wrinkles. Nancy Etcoff, Shannon Stock, Eva G. Krumhuber and Lawrence Ian Reed. Front. Psychol., January 12 2021. https://doi.org/10.3389/fpsyg.2020.612654

Abstract: Smiles that vary in muscular configuration also vary in how they are perceived. Previous research suggests that “Duchenne smiles,” indicated by the combined actions of the orbicularis oculi (cheek raiser) and the zygomaticus major muscles (lip corner puller), signal enjoyment. This research has compared perceptions of Duchenne smiles with non-Duchenne smiles among individuals voluntarily innervating or inhibiting the orbicularis oculi muscle. Here we used a novel set of highly controlled stimuli: photographs of patients taken before and after receiving botulinum toxin treatment for crow’s feet lines that selectively paralyzed the lateral orbicularis oculi muscle and removed visible lateral eye wrinkles, to test perception of smiles. Smiles in which the orbicularis muscle was active (prior to treatment) were rated as more felt, spontaneous, intense, and happier. Post treatment patients looked younger, although not more attractive. We discuss the potential implications of these findings within the context of emotion science and clinical research on botulinum toxin.

Discussion

Virtually all pre-treatment photographs depicted patients displaying Duchenne smiles. These smiles were rated as being happier, more felt, more spontaneous, and more intense than those posed by the same patients under the same conditions and instructions in post-treatment photographs. The photographs were matched for smile intensity (activity of the zygomatic major muscle pulling the lip corner) suggesting that the differences were due to the inhibition of the orbicularis oculi and not by the activity of zygomatic major.

Patients were also rated as being significantly younger after treatment (by approximately 1 year) likely due to less visible crow’s feet lines. There was no effect of treatment on facial attractiveness ratings. Although some have speculated that a more spontaneous smile would make a face more attractive, past research (Mehu et al., 2007b) also found no difference in ratings of attractiveness for faces displaying Duchenne vs. non-Duchenne smiles. As such, attractiveness might be more dependent on the face structure and skin health than on dynamic features.

Interestingly, we found that ratings of smile quality were dependent on sex. The smiles of female patients were rated as more felt, surprised, spontaneous, and intense as well as less sad. This is consistent with data suggesting that women are more expressive for positive valanced facial actions (McDuff et al., 2017).

These data are consistent with results of previous studies demonstrating that Duchenne smiles are perceived differently than non-Duchenne smiles (Hess and Kleck, 1994; Del Giudice and Colle, 2007; Krumhuber and Manstead, 2009; Mehu et al., 2012; Gunnery et al., 2013). Patients in the pre-treatment photographs—consisting almost exclusively of Duchenne smiles—were perceived as feeling more genuine positive emotion in comparison to post-treatment photographs. These data are also consistent with studies reporting high frequencies of Duchenne smiles in deliberate facial action tasks (Kanade et al., 2000; Krumhuber et al., 2020). Together, these findings suggest that although the Duchenne marker can be posed in the absence of positive affect, it is still perceived by others to be indicative of genuine emotion. Future research may benefit from examining potential limitations in the production or inhibition of the Duchenne marker in facial action tasks. Such work could shed new light on how different elicitation conditions might drive the reliability of this signal (McCullough and Reed, 2016; see also Zloteanu et al., 2020 in the context of surprise expressions).

Our results have several potential implications and caveats. Our study did not support the strongest version of the Duchenne hypothesis—that inhibition of the orbicularis oculi would make the smile signal appear unfelt or weak. Non-Duchenne smiles were rated as less happy, genuine, felt, and spontaneous, though our small treatment effects suggest that the effect was subtle. However, our stimulus patients were instructed to pose “maximum smiles” (maximum zygomatic activation). It may be that more pronounced effects on smile authenticity occur with less intense smiles. In general, these small but statistically significant changes could have practical implications in natural contexts where smiles may be less intense and/or the Duchenne marker may be more conspicuous.

Previous research has shown that the Duchenne marker plays a role in communicating cooperative intent (Mehu et al., 2007a, b; Reed et al., 2012) as well as eliciting cooperation from others (Scharlemman et al., 2001; Brown and Moore, 2002). In light of the results of the current study, it is possible that when the Duchenne marker is absent (in this study through chemodenervation that inhibited the orbicularis oculi muscle and erased visible crow’s feet wrinkles) signals of cooperation may be lessened. If so, augmenting other signals of positive affect such as vocal affect or body language may counter the effects. Future studies can test this idea.

The images used in this study were derived from a clinical trial evaluating the efficacy of botulinum toxin on crow’s feet lines. In order to test our hypothesis, we selected a subset of patients who showed no evidence of crow’s feet lines using the Facial Wrinkle Scale post treatment. The majority of patients in the trial (66%), while having clinical improvement, did not have complete elimination of their dynamic lines. Interestingly, the patients in this trial where dynamic lines were eliminated reported feeling more satisfied with their appearance after treatment than those in whom some movement was preserved (unpublished data, Allergan). This suggests a potential disconnect between the positive perception of the aesthetic outcome on the part of the patient and the subtle negative impact on emotion communication as perceived by the observers. While not within the scope of this paper, this tension warrants further exploration. As reported, perceived smile authenticity did not impact attractiveness ratings, and did make patients appear approximately a year younger.

Three specific limitations must be taken into account when interpreting our findings. First, participants rated static images as opposed to video clips. Video clips have been shown to provide richer emotional content in comparison to static images (Ambadar et al., 2005; see Krumhuber et al., 2013, for a review) and would allow for the analysis of timing characteristics of facial expressions (Ambadar et al., 2009). Second, our sample did not include pre- and post-treatment photographs of spontaneously occurring smiles. That is, we were able to test our primary hypotheses using only deliberate facial action tasks and not when patients were experiencing genuine positive emotion (see Namba et al., 2020, for a similar approach). Future research addressing these limitations could complement the present findings and broaden our understanding of the perceptual and behavioral effects of the Duchenne smile. Third, our study was done solely with participants in the United States. It may be that participants in other cultures will be more impacted by the absence of the Duchenne marker. For example, Yuki et al. (2007) found cultural difference in the use of the eyes and mouth as cues to emotion in Japan and the U.S., with participants in Japan relying more heavily on eye expression for determination of emotion, including happiness, and participants in the U.S. on the mouth.

The Duchenne smile was first reported in 1862 by Duchenne de Boulogne in his “Mechanisme de la Physiognomie Humane.” Duchenne isolated facial muscle action using the novel method of electrical contraction of its muscles. These were the first physiological experiments illustrated by photography. Over 150 years later, we used a pharmacological technique to selectively chemodenervate, and therefore isolate specific facial muscles. In doing so, we shed further light on Duchenne’s pioneering ideas and address current controversies. We find evidence that Duchenne smiles communicate genuine and more intense happiness and that complete inhibition of orbicularis oculi leads to subtle yet statistically significant decreases in such communication.

What is remarkable is that, in both studies, those who lean left were more inclined to unfriend someone after a political disagreement than those who lean right

Neubaum G, Cargnino M, Winter S, Dvir-Gvirsman S (2021) “You’re still worth it”: The moral and relational context of politically motivated unfriending decisions in online networks. PLoS ONE 16(1): e0243049. https://doi.org/10.1371/journal.pone.0243049

Rolf Degen's take: https://twitter.com/DegenRolf/status/1348863984494120969

Abstract: Political disagreements in social media can result in removing (i.e., “unfriending”) a person from one’s online network. Given that such actions could lead to the (ideological) homogenization of networks, it is pivotal to understand the psychological processes intertwined in unfriending decisions. This requires not only addressing different types of disagreements but also analyzing them in the relational context they occur. This article proposes that political disagreements leading to drastic measures such as unfriending are attributable to more deeply rooted moral dissents. Based on moral foundations theory and relationship regulation research, this work presents empirical evidence from two experiments. In both studies, subjects rated political statements (that violated different moral foundations) with regard to perceived reprehensibility and the likelihood of unfriending the source. Study 1 (N = 721) revealed that moral judgments of a political statement are moderately related to the unfriending decision. Study 2 (N = 822) replicated this finding but indicated that unfriending is less likely when the source of the morally reprehensible statement is relationally close to the unfriender and provides emotional support. This research extends unfriending literature by pointing to morality as a new dimension of analysis and offers initial evidence uncovering the psychological trade-off behind the decision of terminating digital ties. Drawing on this, our findings inform research on the homogenization of online networks by indicating that selective avoidance (in the form of politically motivated unfriending) is conditional upon the relational context and the interpersonal benefits individuals receive therein.

Check also What Do We Fear? Expected Sanctions for Expressing Minority Opinions in Offline and Online Communication. German Neubaum, Nicole C. Krنmer. Communication Research, Jan 2018. https://www.bipartisanalliance.com/2018/01/expected-sanctions-for-expressing.html

General discussion

The present studies focused on the phenomenon of politically motivated unfriending as a consequence of a moral disagreement. To this end, it examined (a) whether moral judgments are at work when reading political statements on social networking platforms, (b) whether and which moral evaluations have predictive value for the decision to politically “filtrate” one’s online network, and (c) to what extent moral judgements of political statements are undertaken differently depending on the relational context and the social rewards the source of political statement offers.

Study 1 and 2 partly replicated previous findings on characteristics of who are political unfrienders: Those who use social networking sites (in this case: Facebook) more frequently might encounter political dissents among their network more often and, therefore, they are more likely to unfriend or block someone [5, 8, 23]. Likewise, those who are more interested in politics feel more involved in certain political issues and, thus, perceive political disagreements as more severe, leading them to unfriend or block the dissenter [7]. What is remarkable is that, in both studies, those who lean left were more inclined to unfriend someone after a political disagreement than those who lean right. The fact that this result was not obtained consistently in previous research [4, 5, 27] may be explained by the national context and prevailing issues that are predominantly discussed in online networks at the time the study was conducted. It seems conceivable that in Germany (the country this research was conducted in 2017 and 2018), the debate about the immigration of refugees–as a rather dominant topic in the public [61]–might have led left-leaning users to unfriend or block those ties who opposed the immigration. Moreover, in contrast to previous findings [5, 23], higher political extremity was not associated with the likelihood of unfriending someone. This additionally suggests that the predictive value of the political identity or orientation on decisions of network filtrations depends on the current political landscape and state of polarization in certain countries.

While the present studies replicated certain findings from previous research, these factors only explained a limited variance of unfriending behavior (approx. 5% in both studies). In contrast to this, the present approach of focusing on the moral and relational nature of an unfriending decision appears to have greater explanatory value: First, both studies offered compelling evidence that evaluating a political statement on SNS as morally wrong is a driver of the decision to unfriend or block someone. This finding supports the notion that political disagreements that lead to the post hoc modification of one’s online network are rooted in moral discrepancies. Following this logic, Study 1 showed that individuals are able to differentiate between two different sets of moral foundations that a political statement on SNS violates: When the foundations of care/harm and fairness are trespassed, individuals seem to be slightly more inclined to unfriend someone than when the moral domains of loyalty, authority, or purity are violated. While Study 2 did not indicate main effects of the type of moral foundations violated, it showed that perceiving trespasses of individualizing foundations were slightly stronger associated with unfriending than perceived violations of binding foundations. Likewise, considering past behavior, users reported that violations of individualizing foundations were more likely to lead to unfriending decisions than trespasses of binding foundations. Collectively, this evidence is indicative for the role that morality and its nuances play when it comes to shaping one’s online network by terminating a digital relationship. In line with previous research, it seems that the stronger adherence to individualizing foundations in Western countries [22, 57] relative to binding foundations is also reflected in the way individuals deal with political statements in their online network. Given the patterns observed in the present research, the question arises whether there is a likelihood that online networks become clustered by moral foundations, potentially leading to a disconnection between those who prioritize individualizing versus those who prioritize binding foundations. While previous empirical research did not corroborate the notion that social media users are captivated in politically like-minded cocoons [9–11], it seems worthwhile to assume a more complex view and examine whether sub-networks in online communication can be characterized by homogenous moral values. As suggested by Greene [62], the investigation of moral conflicts and their related emotional tensions could contribute to explaining modern tribalism, potentially also in online environments.

The threat that online communication leads to full moral clustering, though, appears rather unlikely as is suggested by Study 2 when the relational context is taken into account. In line with previous works [2, 5], in disregard of the moral violation, people were more unlikely to unfriend or block someone when this person was relationally close (compared to relationally distant). The findings also offer an explanation why: Since relationally closer ties are more likely to offer emotional support [30], individuals seem to be willing to tolerate moral violations and not terminate the digital tie, in return of maintaining the reception of social support. This result clearly shows the boundaries of the predictive value of a moral judgment in relation to a political statement and indicates the importance of a relational context for consideration. This research, thus, represents a first step to theorize the inner trade-off individuals go through when making a decision about digital interpersonal relationships in the face of political debates. In a nutshell, a specific type of social support, that is, emotional support, seems to be an inhibitor of terminating a digital connection when exposed to a political statement that violates a moral foundation. In light of the vivid debate on users’ active homogenization of their online networks in terms of “echo chambers” [14, 15], this novel theoretical link between political disagreements, moral judgments, and interpersonal context in contemporary communication technologies reveals that there are boundaries to users’ selective avoidance of dissents. These boundaries seem to come into play when individuals can gain something from certain relationships (i.e., network ties). A psychological view on users’ decision to unfriend or block someone offers a fruitful ground for the discussion about why political and probably also moral diversity emerges and prevails in individuals’ online networks [10, 15, 41].

The present findings need to be interpreted in light of this research’s limitations. First, although this work assessed individuals’ past unfriending and blocking behavior, it predominantly employed a scenario-based approach relying on hypothetical unfriending decisions. Both types of measures, though, seem to offer concurring findings: Those who indicated that they had unfriended because of a political disagreement in the past were significantly more likely to express a higher likelihood of unfriending in the hypothetical scenarios (on a five-point scale/ Study 1: M = 2.96, SD = 0.90; Study 2: M = 3.27, SD = 1.20) than those who did not unfriend because of political reasons in the past (Study 1: M = 2.67, SD = 1.07; Study 2: M = 2.53, SD = 1.25) (Study 1: t(301.62) = -3.49, p = .001, Cohen’s d = -.29 / Study 2: t(583) = -6.58, p < .001, Cohen’s d = -.60). Participants’ answers on previous politically motivated unfriending actions also corroborated the relative importance of individualizing moral foundations, the role of relational closeness and social support. Thus, both studies reveal a significant connection between what participants told they did in the past and what they would do. Objective observations on how online networks and their potentially moral clusters change over time or mobile experience sampling questionnaires on users’ smartphones, though, would be an informative complement to the present research.

Second, while the present work speculates about the motivation behind unfriending decisions, the psychological processes at work are still to be uncovered. For instance, it is unclear to what extent unfriending decisions are driven by cognitive or by affective processes. Given that moral conflicts are often fueled by emotions [62], it seems plausible to assume that not every unfriending decision is the result of a rational calculus of costs and benefits when dissolving this relationship. Future research could address the psychological mechanisms behind the creation and modification of one’s online political network in a systematic manner.

Third, the composition of our samples should be taken into account. The fact that female and left-leaning participants (see A4 and A10 Figs in S1 File) were overrepresented in Study 1 leads to the question of how these variables influence unfriending decisions. While the gender-balanced sample of Study 2 indicates that politically motivated unfriending does not occur more often among women than among men, χ2 (1) = .61, p = .434, both studies revealed that left-leaning individuals (compared to right-leaning ones) are more likely to unfriend others. It seems worthwhile to scrutinize whether a certain political ideology comes with enhanced involvement in certain topics which, in turn, could lead to less tolerance (and a higher unfriending likelihood) when disagreements come up or whether this finding was due to the specific national context and selected topics.

To conclude, the present work extends previous research by providing initial evidence for the importance of morality as a link between encountering politically challenging content online and actively banning this kind of information from one’s news feed. If users estimate another user’s political comment to be morally wrong, they will be more likely to terminate the digital relationship with this person. The power of morality, though, is limited when users are aware of the social resources, i.e., emotional support, that the person that is potentially to be unfriended can offer. This research, thus, presents a new level of analysis in online networks that could contribute (a) to understand the potential of social media communication to foster (moral) tribalism and (b) to identify the limits of this potential moral segregation in light of the social benefits human beings provide to one another.

The brain: Different expert systems propose strategies for action, keeping track of the precision of the predictions within each system, exerting control over many different expert systems simultaneously to produce sophisticated behavior

Why and how the brain weights contributions from a mixture of experts. John P. O’Doherty et al. Neuroscience & Biobehavioral Reviews, January 11 2021. https://doi.org/10.1016/j.neubiorev.2020.10.022

Rolf Degen's take: https://twitter.com/DegenRolf/status/1348683591333670914

Highlights

• The brain can be thought of as a “Mixture of Experts” in which different expert systems propose strategies for action.

• This is accomplished by keeping track of the precision of the predictions within each system, and by allocating control over behavior in a manner that depends on the relative reliability of those predictions.

• This reliability-based control mechanism is domain general, exerting control over many different expert systems simultaneously in order to produce sophisticated behavior.

Abstract: It has long been suggested that human behavior reflects the contributions of multiple systems that cooperate or compete for behavioral control. Here we propose that the brain acts as a “Mixture of Experts” in which different expert systems propose strategies for action. It will be argued that the brain determines which experts should control behavior at any one moment in time by keeping track of the reliability of the predictions within each system, and by allocating control over behavior in a manner that depends on the relative reliabilities across experts. fMRI and neurostimulation studies suggest a specific contribution of the anterior prefrontal cortex in this process. Further, such a mechanism also takes into consideration the complexity of the expert, favoring simpler over more cognitively complex experts. Results from the study of different expert systems in both experiential and social learning domains hint at the possibility that this reliability-based control mechanism is domain general, exerting control over many different expert systems simultaneously in order to produce sophisticated behavior.

Keywords: cognitive controlPrefrontal cortexbasal gangliaTheoretical neuroscienceDecision-making

Conclusion

Here we outline a framework for conceptualizing the contribution of multiple systems to behavioral control in the human brain. We suggest that the brain utilizes a framework loosely analogous to the mixture of experts in machine learning, in which a prefrontal-based manager (which we hypothesize specifically involves the ventrolateral prefrontal cortex), reads out the reliability of the predictions by each of the constituent experts, and uses these predictions to allocate control over behavior to the experts in a manner that is proportional to the relative precision or uncertainties in their predictions. We suggest that this reliability-based arbitration process between experts is both necessary and sufficient for the efficient allocation of control between systems, as this approach takes into account not only the accuracy and hence the average expected value of the actions nominated by each expert, but also implicitly takes into account the cognitive costs and cognitive constraints. The interaction between systems that makes up the experts is we suggest, better conceived of as one of polling the advice from different systems that each have different relevant expertise that can and should be respected owing to differences in the nature of the information that is being processed, and in the algorithmic transformations that are performed on that information. These experts should be listened to as a collective, because they provide the right mixture of opinions needed to act in the world effectively.

Our results suggest that the theory cannot fully explain human aesthetic responses to flowers and clear preferences for them

Hula, M., & Flegr, J. (2021). Habitat Selection and Human Aesthetic Responses to Flowers. Evolutionary Human Sciences, 1-49. doi:10.1017/ehs.2020.66

Abstract: Although the aesthetic appreciation of flowers is a well-known aspect of human behaviour, theories explaining its origin are missing. The only exception is the evolutionary theory of Heerwagen and Orians. Surprisingly, it has not yet been empirically tested. The authors suggest that humans aesthetically respond to flowers because they signal food availability. The logic of the theory implies that fruits are more reliable and direct food availability signals than flowers. Therefore, fruits should elicit stronger aesthetic responses than flowers. To test this assumption, we performed two online studies in the Czech Republic. The participants (n = 2792 and 744 respectively) indicated on a six-point scale their aesthetic response to photographs of 14 edible Czech plant species (study A) and 20 edible plant species from African savannas (study B), varying in growth stage (flowering, fruiting). We found no difference between the Czech fruiting and flowering plants and a stronger aesthetic response to African flowering plants. A third study (n = 816) confirmed that flowers were preferred to fruits, using a forced-choice paradigm. Our results suggest that the theory cannot fully explain human aesthetic responses to flowers. We discuss alternative explanations. This topic deserves renewed attention from researchers working in related fields.

Social Media summary: Contrary to the assumptions of the habitat selection theory, flowers elicit stronger aesthetic responses than fruits.

Keywords: evolutionary aesthetics, habitat selection, flower preference, perception of flowers

Sexual prejudice toward gays is rooted in working-class experiences; contrary to mainstream ideas, social class matters in contemporary society, the relationship is not spurious, & education is not the main issue

Class Foundations of Sexual Prejudice toward Gay and Lesbian People. Stef Adriaenssens, Jef Hendrickx & Johanna Holm. Sexuality Research and Social Policy, Jan 11 2021. https://rd.springer.com/article/10.1007/s13178-020-00525-y

Abstract

Introduction: Sexual prejudice negatively affects the quality of life and life chances of those involved. Manual workers are consistently found to be less accepting of homosexuality in studies of sexual conformism. This can be seen as an application of Lipset’s ‘working class conformism’. Our core hypothesis is that this lower tolerance is rooted in working-class experiences. Counter-arguments are that that social class does not matter in contemporary society and that the relationship is spurious, with education as the true cause.

Methods: We test the central hypothesis with European survey data. First, we regress sexual prejudice on time trends and class with repeated cross-sections from the European Social Survey, ranging from 2002 to 2016. As an extra check, this is also applied to the European Values Study, going back to 1981. Further, we test the spuriousness argument with a matching design, testing whether stratification accounts for the lag.

Results: The time series shows a stable lag between working-class members and others against the general trend of decreasing sexual prejudice. The matching design provides evidence that working-class membership in itself is a factor behind differences in sexual prejudice.

Conclusions: Contrary to ‘death of class’ conjectures, working-class membership is related to sexual prejudice. This contribution shows that this gap is due to experiences of belonging to the working class and not solely to educational differences.

Policy Implications: Occupational experiences, especially in low-skill manual labour, have social effects in areas such as sexual prejudice. Improving the quality of work thus facilitates a more inclusive society for sexual minorities.

Chimpanzees stopped bartering when the human no longer mediated the trade; the authors think that the issue holding them back was an inability to trust their partners & a lack of third party enforcement mechanisms

What behaviour in economic games tells us about the evolution of non-human species' economic decision-making behaviour. Sarah F. Brosnan. Philosophical Transactions of the Royal Society B: Biological Sciences, Volume 376, Issue 1819, January 11 2021. https://doi.org/10.1098/rstb.2019.0670

Rolf Degen's take: https://twitter.com/DegenRolf/status/1348531514955460609

Abstract: In the past decade, there has been a surge of interest in using games derived from experimental economics to test decision-making behaviour across species. In most cases, researchers are using the games as a tool, for instance, to understand what factors influence decision-making, how decision-making differs across species or contexts, or to ask broader questions about species’ propensities to cooperate or compete. These games have been quite successful in this regard. To what degree, however, do these games tap into species' economic decision-making? For the purpose of understanding the evolution of economic systems in humans, this is the key question. To study this, we can break economic decision-making down into smaller components, each of which is a potential step in the evolution of human economic behaviour. We can then use data from economic games, which are simplified, highly structured models of decision-making and therefore ideal for the comparative approach, to directly compare these components across species and contexts, as well as in relation to more naturalistic behaviours, to better understand the evolution of economic behaviour and the social and ecological contexts that influenced it. The comparative approach has successfully informed us about the evolution of other complex traits, such as language and morality, and should help us more deeply understand why and how human economic systems evolved.

Check also Acquisition of object-robbing behavior in macaques: After stealing inedible & more or less valuable objects from humans, they appear to use them as tokens, by returning them to humans in exchange for food

Acquisition of object-robbing and object/food-bartering behaviours: a culturally maintained token economy in free-ranging long-tailed macaques. Jean-Baptiste Leca, Noëlle Gunst, Matthew Gardiner and I. Nengah Wandia. Philosophical Transactions of the Royal Society B: Biological Sciences, Volume 376, Issue 1819, January 11 2021. https://www.bipartisanalliance.com/2021/01/acquisition-of-object-robbing-behavior.html

4. What can we say about the evolution of economic systems?

Economic games are a model system that allows for close comparisons across contexts and species [46]. However, they are not intended to be natural situations, thus the data generated are best used to test hypotheses generated from observational or experimental work and generate new hypotheses that may be tested with more species-specific and/or naturalistic approaches [8]. While this can be done in diverse ways, there are two literatures that obviously connect to the existing data on experimental economics, that on cooperation and that on trade. Both literatures are extensive enough for entire reviews on their own, but I briefly discuss them as they tie into the main points raised above.

The assurance game highlights the fact that not all species coordinate, and even among those that do, coordination may be achieved by different underlying mechanisms. This reflects their behaviour in natural contexts as well. For instance, in capuchins, group territorial defence (i.e. [47]) and coordinated defence against predators (i.e. snake mobbing: [48]) are typically done among individuals with a clear view of one another and in situations in which all individuals are performing similar actions. This is reminiscent of capuchins’ behaviour in the Assurance game, in which they appeared to coordinate by matching their partners, and only achieved coordination when they could see the other's outcomes. This suggests that behaviour matching is a key mechanism for coordination in capuchins, possibly facilitated by behavioural synchrony and/or social facilitation. Indeed, although capuchins in experimental contexts can solve coordination tasks that require different actions (i.e. [41]), this was a rather simple case in which individuals could see one another and performed actions that they previously learned individually as a sequence.

On the other hand, chimpanzees show more complex coordinated behaviour, such as the coordinated hunting in which different individuals take on different roles, seen in some populations [49], which presumably requires an ability to understand the larger picture. This, too, matches their behaviour in the economic games, in which at least some chimpanzees (those with extensive experience with cognitive tasks) extrapolated to novel options in coordination games, suggesting that they understood their choice as part of a larger strategy. In some experimental contexts, too, chimpanzees show evidence of understanding the bigger picture, for instance choosing to benefit, at a cost to themselves, a chimpanzee that previously paid a cost to make that choice available [44]. Such specificity in how they make decisions suggests that they see their choice within a broader framework.

This synchrony between the outcomes of the highly structured economic games and these primates' natural behaviours suggests that the games are indeed useful models. They allow for studying mechanisms that may be impossible to study in more natural situations and for comparison across populations or species, and may be particularly helpful if differences in body form or ecology make it impossible to compare in more naturalistic contexts. Within the same population or species, these games can also be used to generate new hypotheses regarding behaviour, and the mechanisms underlying it, in more naturalistic contexts. Future work using more naturalistic experimental tasks, like the cooperative barpull (reviewed in [50]), or field-based experiments (as has been done in social learning research; [51]) that combine the naturalistic contexts of the observational work with the structured methodology of the economic games will help determine the limits and flexibility of the different species’ coordination ability and the cognitive mechanisms that underlie them.

We can similarly learn from how primates trade goods and services. Primates' ability to find the NE in economic games suggests that they should be able to maximize their outcomes in barter, too. Indeed, in natural contexts, primates do trade, although typically this involves services (grooming, support in conflicts, and mating opportunities) rather than goods (there are exceptions; for instance, chimpanzees trade meat for mating opportunities and support; [52]). There are several possible reasons for this; objects are zero sum commodities, and few items in primates’ natural lives are worth trading, as most are either easy to acquire or cannot be stored for future trades [5]. This does suggest, however, that they should trade objects when it is worth doing so, and indeed, in experimental tasks, primates trade tokens with experimenters (or, sometimes, other primates) in order to obtain different food rewards (see Addessi et al. [53] and Beran & Parrish [54]). Some macaques have even spontaneously developed exchange systems with humans in free-ranging contexts [55].

What is notably absent, however, is the transfer of these barter relationships with humans to trade with one another. We tested this among three highly trained chimpanzees at Georgia State's Language Research Center (the same chimpanzees that showed evidence of strategy use in the Assurance game). These chimpanzees had been taught a symbol language that allowed us to communicate with more specificity than is typically possible [56]. We made tokens representing specific foods (labelled by their symbol) that they could exchange back to an experimenter for food if—and only if—that food was present in their personal bin. In a series of tasks, we then explored whether the chimpanzees would learn to trade tokens that were of no value to them (because the food was not in their bin) to a partner to whom the tokens were valuable (because the food was in the partner's bin) so as to maximize both chimpanzees' benefits [57].

To cut a long story short, the chimpanzees learned to do so effectively as long as a human experimenter mediated the interactions such that neither chimpanzee could exchange a token with the experimenter for food until they had reciprocated any trades from the partner (we did not restrict which token they had to trade to a partner, just that they traded something). Despite having previously maximized their rewards, within one session of us removing experimenter-mediated quid pro quo, the chimpanzees ceased trading any tokens with their partners. Since they demonstrated all of the necessary cognitive abilities to understand trade, we hypothesized that the issue holding them back was an inability to trust their partners and a lack of third party enforcement mechanisms to make doing so worthwhile [57].

In concert with the results from experimental games, this suggests that at least some primates have the cognitive ability to understand these strategies and maximize their outcomes, which may be evident in service markets, but lack the enforcement mechanisms that lead to beneficial trade of goods. This is important for two reasons. First, it suggests that even these very structured, artificial laboratory situations are indeed useful for understanding the true scope of primates’ abilities, by removing factors that may inhibit expression. Second, this suggests that primates have a more developed set of abilities related to economic behaviour than is necessarily indicated in their natural behaviour. This not only guides future research aimed at understanding economic behaviour in natural contexts, but suggests that humans' abilities are not as separate from the other primates' as we might think. Indeed, this isn't the only context in which experimental tasks have revealed such similarities; primates also share psychological adaptations related to economic decision-making, such as the endowment effect [58] and framing effects [59,60]. Increasing evidence suggests that other species have the cognitive toolkit for economic behaviour and simply lack the opportunity to use it.

If this is the case, our next step is twofold. First, we must explore the range of economic behaviours in other species, ideally with the goal of delineating possible underlying cognitive mechanisms, and determine the contexts in which animals show these behaviours and how they are influenced by changes in social and ecological context. This will require creative experimental studies (both in the laboratory and, hopefully, in the field) to unpack what underlying abilities are present and when they manifest, as well as observational research to determine if related behaviours are seen in more natural contexts [61]. Indeed, further work in this area will also help to clarify the degree to which these abilities were selected specifically for this context versus others. Second, to more fully understand the cognitive precursors to economic behaviour, we also need to look beyond the primates. Although there has been work in this direction already, with studies of economic game behaviour in species as diverse as birds [62], rodents [63] and fish [64,65], even in those cases the focus has been on one or a few species. A more diverse approach is important for understanding how economic behaviour evolved; species vary in their needs, so a broad exploration will inform our understanding of the contexts, environments and pressures that selected for different economic behaviours. Ultimately, this will clarify how these abilities expanded so greatly in humans to result in the complex economic systems we enjoy today.

After group conversations, people underestimated how much they were liked by others; people focus on negative aspects of the impressions they make on others

The liking gap in groups and teams. Adam M. Mastroianni et al. Organizational Behavior and Human Decision Processes, Volume 162, January 2021, Pages 109-122. https://doi.org/10.1016/j.obhdp.2020.10.013

Rolf Degen's take: https://twitter.com/DegenRolf/status/1348524602255880192

Highlights

• After group conversations, people underestimated how much they were liked by others.

• This liking gap persisted in engineering teams working together on group projects.

• The effect was larger among peers than between supervisors and supervisees.

• The liking gap also had important consequences in a general sample of working adults.

• Consequences include team communication and efficacy as well as job satisfaction.

Abstract: Every relationship begins with a conversation. Past research suggests that after initial conversations, there exists a liking gap: people underestimate how much their partners like them. We extend this finding by providing evidence that it arises in conversations among small groups (Study 1), continues to exist in engineering teams working on a project together (Study 2), and is linked to important consequences for teams’ ability to work together in a sample of working adults (Study 3). Additional evidence suggests that the liking gap is largest for peer relationships and that it is determined in part by the extent to which people focus on negative aspects of the impressions they make on others. Group conversations and team interactions often leave people feeling uncertain about where they stand with others, but our studies suggest that people are liked more than they know.

Keywords: ConversationSocial interactionRelationship formationMeta-perceptionGroup dynamicsTeams

Acquisition of object-robbing behavior in macaques: After stealing inedible & more or less valuable objects from humans, they appear to use them as tokens, by returning them to humans in exchange for food

Acquisition of object-robbing and object/food-bartering behaviours: a culturally maintained token economy in free-ranging long-tailed macaques. Jean-Baptiste Leca, Noëlle Gunst, Matthew Gardiner and I. Nengah Wandia. Philosophical Transactions of the Royal Society B: Biological Sciences, Volume 376, Issue 1819, January 11 2021. https://doi.org/10.1098/rstb.2019.0677

Abstract: The token exchange paradigm shows that monkeys and great apes are able to use objects as symbolic tools to request specific food rewards. Such studies provide insights into the cognitive underpinnings of economic behaviour in non-human primates. However, the ecological validity of these laboratory-based experimental situations tends to be limited. Our field research aims to address the need for a more ecologically valid primate model of trading systems in humans. Around the Uluwatu Temple in Bali, Indonesia, a large free-ranging population of long-tailed macaques spontaneously and routinely engage in token-mediated bartering interactions with humans. These interactions occur in two phases: after stealing inedible and more or less valuable objects from humans, the macaques appear to use them as tokens, by returning them to humans in exchange for food. Our field observational and experimental data showed (i) age differences in robbing/bartering success, indicative of experiential learning, and (ii) clear behavioural associations between value-based token possession and quantity or quality of food rewards rejected and accepted by subadult and adult monkeys, suggestive of robbing/bartering payoff maximization and economic decision-making. This population-specific, prevalent, cross-generational, learned and socially influenced practice may be the first example of a culturally maintained token economy in free-ranging animals.

4. Discussion

This field observational and experimental study of token-robbing and token/reward-bartering interactions in the free-ranging population of Balinese long-tailed macaques produced three main findings: (i) these behaviours need to be learned throughout juvenescence (i.e. until up to 4 years in this species) to be successfully performed; (ii) older monkeys preferentially selected tokens that were more valued by humans; and (iii) these more skilful and selective individuals appeared to make economic decisions, as evidenced by clear behavioural associations between value-based token possession and quantity or quality of food rewards rejected and accepted.

(a) Experiential learning

As predicted, we found a significant increase in token-robbing success from juveniles to subadults to adults, whereas the main behaviour patterns required for the successful performance of token/reward-bartering interactions were already in place from around 4 years (i.e. in subadults). Likewise, the ability to engage in more negotiated successful token/reward-bartering sequences—during which the monkey only returned the token after being proposed more food rewards, or after rejecting more food rewards, or after accepting a type of food reward different from the one(s) previously rejected—was not fully acquired before the subadult stage.

These results lend some support to the ‘experiential learning' hypothesis, whereby token-robbing and token/reward-bartering interactions are multi-stepped and complex behavioural sequences requiring perceptual learning, sensorimotor coordination and cognitive skills (e.g. memory, associative learning) to be successfully performed; they are thus gradually acquired through extended individual practice during the juvenile period, in part via experiential trial-and-error learning. It is noteworthy to mention that the development of (sub)adult-level proficiency at robbing/bartering is not only dependent on skill learning (e.g. detection, sneaky approach, self-control), but may also be constrained by physical maturation. This is particularly true during the token-robbing phase that often involves monkey–human body contact and/or requires muscular strength when a monkey has to yank on a flip-flop still worn by an adult human. In these cases, the limited physical capabilities of juveniles, and the maturing bodies of subadults, may partly explain the significant increase in token-robbing success from juveniles to subadults to adults.

Primates are characterized by the longest juvenile period in relation to life span of all mammals [20]. According to the ‘needing-to-learn' hypothesis [20], prolonged juvenility is associated with behavioural patterns that necessitate acquiring a proportionally large amount of information and/or skills to reach adult competence before individuals become reproductively mature. These behaviours include extractive foraging techniques [21] and (socio-)sexual behaviour patterns [22]. Our study indicates that both phases of the robbing/bartering practice also required experiential learning to be fully mastered.

(b) Value-based token selection

The first step in economic decision-making requires the cognitive ability to distinguish among different expected material values of a given symbolic currency (e.g. tokens, cash, virtual money). After showing that token selection was not significantly affected by token availability and the relative ease with which different types of tokens were stolen by the monkeys from human targets, our observational data revealed a marked age difference in how the monkeys responded to a human-based three-level hierarchy of valuable objects. When considering the token selection among all the prospective human targets (i.e. temple visitors with potential tokens available in a given area), juveniles did not show any preferential selection among low-valued, medium-valued and high-valued tokens, whereas subadults and adults preferentially selected high- and medium-valued tokens over low-valued ones. When two tokens of different values were available on a given human target, subadults and adults preferentially selected the higher-value token, whereas juvenile individuals did not show any significant difference. We found a similar age difference in the value-based token selection, after experimentally controlling for token accessibility and lateral bias.

These results support the ‘value-based token selection' hypothesis, positing age differences in the selection of higher-valued tokens by the monkeys during the token-robbing phase that are indicative of a developmental trajectory toward more strategic choices in more mature individuals. Subadult and adult monkeys (but not juveniles yet) have learned to map their token-robbing behaviours onto the hierarchical (and arbitrary) scale of values attributed by humans to different tokens: they preferentially selected tokens that were more likely to be exchanged for food (e.g. electronic devices, pairs of glasses) over other objects that were less valuable for humans and typically not worth bartering (e.g. empty camera bags, hairpins). Our findings are consistent with data obtained in other non-human primate species, showing that subadult and adult capuchin monkeys and chimpanzees correctly preferred a high-valued token over a low-valued token in an experimental bartering situation [1,11,23].

(c) Robbing/bartering payoff maximization

The second step in economic decision-making requires the cognitive ability (i.e. mental processes involving associative learning and memorization) to respond differently to differentially valued tokens by trying to maximize one's payoff. We found evidence for such behavioural associations between value-based token possession and quantity or quality of food rewards rejected and accepted by subadult and adult monkeys (i.e. the most skilful and selective individuals) during the token/reward-bartering phase. They consistently and actively obtained either more food rewards or a more preferred food reward in exchange for a higher-valued token. They were also more likely to end a successful bartering interaction by accepting a less preferred food reward in exchange for a lower-valued token.

Our findings support the ‘robbing/bartering payoff maximization' hypothesis in that subadult and adult monkeys strategically responded to differentially valued tokens in their possession by adjusting the amount or type of food rewards they gained from the barters. The result showing that subadults (unlike adults) failed to significantly reject more low-preferred food rewards before returning a higher-valued token may be explained in terms of poorer temporal cognition or higher impulsivity (compared to adults): subadult long-tailed macaques may either not have yet acquired the cognitive capacity to anticipate the subsequent proffering of more preferred food rewards in this specific situation, or not be patient/self-controlled enough to wait for possibly more preferred food rewards.

Overall, our field observational data are in line with laboratory-based studies showing that several non-human primate species can (i) understand the effectiveness of tokens as secondary reinforcements to make simple calculations about quantities of reward, (ii) determine an item's value on the basis of its perceived utility (e.g. exchanging only a low-preferred reward for a tool necessary to reach a more preferred reward) and (iii) recognize the appropriate conditions in which a successful exchange could occur (e.g. presence/absence of the experimenter, safe/risky experimenter) [1,2,23–27]. Other cognitive skills and temperamental traits exhibited to varying extents by non-human primates engaging in token-aided economic behaviours include preference transitivity, self-control, delay of gratification, action planning and calculated reciprocity, because they may facilitate or constrain an individual's ability to make optimal economic decisions [1,5,23,28]. Even though these characteristics were not explicitly examined in this study, some of them will be the subject of our future observational and experimental investigations.

The origins of human variation in human economic behaviour: Comparative studies of other primates can help disentangle the relative role of shared biological processes vs human-unique cultural influences in risk preferences

Variation in primate decision-making under uncertainty and the roots of human economic behaviour. Francesca De Petrillo and Alexandra G. Rosati. Philosophical Transactions of the Royal Society B: Biological Sciences, Volume 376, Issue 1819, January 11 2021. https://doi.org/10.1098/rstb.2019.0671

Rolf Degen's take: https://twitter.com/DegenRolf/status/1348516690167029766

Abstract: Uncertainty is a ubiquitous component of human economic behaviour, yet people can vary in their preferences for risk across populations, individuals and different points in time. As uncertainty also characterizes many aspects of animal decision-making, comparative research can help evaluate different potential mechanisms that generate this variation, including the role of biological differences or maturational change versus cultural learning, as well as identify human-unique components of economic decision-making. Here, we examine decision-making under risk across non-human primates, our closest relatives. We first review theoretical approaches and current methods for understanding decision-making in animals. We then assess the current evidence for variation in animal preferences between species and populations, between individuals based on personality, sex and age, and finally, between different contexts and individual states. We then use these primate data to evaluate the processes that can shape human decision-making strategies and identify the primate foundations of human economic behaviour.

5. Conclusion: primate decision-making and human economic origins

Humans exhibit great variation in responses to risk across populations, individuals and contexts, so understanding the origins of this variation is crucial to explaining patterns of human economic behaviour. We have argued that comparative studies of decision-making can disentangle the mechanisms and the function of this variation to address questions about both the proximate mechanisms and the ultimate consequences of these decision-making patterns. As such, non-human primates provide a complementary line of evidence to test hypotheses about the origins of human economic behaviours (figure 2).

Figure 2. The origins of human variation in human economic behaviour. Comparative studies of other primates can help disentangle the relative role of shared biological processes versus human-unique cultural influences in risk preferences. Current evidence for variation across populations, individuals and contexts in primates suggests some processes are shared with humans whereas others are human-unique.

We found that non-humans sometimes show patterns of variation like those in humans. For example, emotional states, social context and some neurotransmitter systems can modulate risk preferences in primates like in humans. This suggests that at least some of the proximate psychological mechanisms driving human economic behaviour build upon cognitive, emotional and neurobiological substrates that are shared with other primates Yet other mechanisms may be more specific to humans: while humans show robust gender differences in risk preferences as well as developmental change over the life-course, there is limited evidence for parallel shifts in non-human risky choice. This suggests that this variation may stem more from human-specific mechanisms, such as cultural learning and socialization. Given that culturally based traits are more malleable and thus more amenable to interventions, this provides new clues for promoting optimal economic behaviour in humans.

A second question concerns the ultimate consequences of variation in risk preferences. Here, comparative work can provide an important line of evidence to test the adaptive consequences of different strategies. For example, there are robust species differences in responses to risk indicating that species that typically feed on more variable, heterogeneous resources are relatively more risk-seeking. Yet there are also crucial differences in human and animal patterns that may stem from humans' novel socioecological niche. Human hunter–gatherer lifestyles are characterized by a dependence on high-value and high-risk foods that may have required new social mechanisms to cope with a greater variability in foraging, such as food sharing and resource redistribution [107,116]. As a consequence, humans might have evolved new cognitive abilities and innovated new cultural practices to deal with the social risks presented by exchanges.

Yet there is still much work to be done. First, different species and questions have sometimes been tested using different tasks (figure 1), limiting some inferences across studies. In addition, primate studies, in general, are often limited by small sample sizes, especially with respect to questions of intra-individual variation. As such, comparisons of decision-making using standardized methods in larger populations with wider variation in sex, ages or particular life experiences are crucial to test these ideas. Finally, the animal choice typically involves biologically relevant rewards, but there is increasing evidence that people can be more risk-seeking when making ‘foraging’ decisions about food than in equivalent decisions involving money [67,103]. Given that humans engage in evolutionarily novel forms of economic exchange involving abstract currencies, but other primates can be trained to use and exchange tokens in specific contexts [84], animals thus present untapped opportunities to test how experience with markets impacts economic decision-making. More generally, comparative research is well-positioned to advance our understanding of human economic behaviour by pinpointing the necessary cognitive and experiential prerequisites that enable different aspects of decision-making and exchange.