Irrelevant-action imitation is short-term and contextual: Evidence from two under-studied populations.

Across the lifespan and across populations, humans 'overimitate' causally unnecessary behaviors. Such irrelevant-action imitation facilitates faithful cultural transmission, but its immediate benefits to the imitator are controversial. Over short time scales, irrelevant-action imitation may bootstrap artifact exploration or interpersonal affiliation, and over longer time scales it may facilitate acquisition of either causal models or social conventions. To investigate these putative functions, we recruited community samples from two under-studied populations: Yasawa, Fiji, and Huatasani, Peru. We use a two-action puzzle box: first after a video demonstration, and again one month later. Treating age as a continuous variable, we reveal divergent developmental trajectories across sites. Yasawans (44 adults, M = 39.9 years, 23 women; 42 children, M = 9.8 years, 26 girls) resemble documented patterns, with irrelevant-action imitation increasing across childhood and plateauing in adulthood. In contrast, Huatasaneños (48 adults, M = 37.6 years, 33 women; 47 children, M = 9.3 years, 13 girls) evince a parabolic trajectory: adults at the site show the lowest irrelevant-action imitation of any demographic set in our sample. In addition, all age sets in both populations reduce their irrelevant actions at Time 2, but do not reduce their relevant-action imitation or goal attainment. Taken together, and considering the local cultural contexts, our results suggest that irrelevant-action imitation serves a short-term function and is sensitive to the social context of the demonstration.

On the deep structure of social affect: Attitudes, emotions, sentiments, and the case of "contempt".

Contempt is typically studied as a uniquely human moral emotion. However, this approach has yielded inconclusive results. We argue this is because the folk affect concept "contempt" has been inaccurately mapped onto basic affect systems. "Contempt" has features that are inconsistent with a basic emotion, especially its protracted duration and frequently cold phenomenology. Yet other features are inconsistent with a basic attitude. Nonetheless, the features of "contempt" functionally cohere. To account for this, we revive and reconfigure the sentiment construct using the notion of evolved functional specialization. We develop the Attitude-Scenario-Emotion (ASE) model of sentiments, in which enduring attitudes represent others' social-relational value and moderate discrete emotions across scenarios. Sentiments are functional networks of attitudes and emotions. Distinct sentiments, including love, respect, like, hate, and fear, track distinct relational affordances, and each is emotionally pluripotent, thereby serving both bookkeeping and commitment functions within relationships. The sentiment contempt is an absence of respect; from cues to others' low efficacy, it represents them as worthless and small, muting compassion, guilt, and shame and potentiating anger, disgust, and mirth. This sentiment is ancient yet implicated in the ratcheting evolution of human ultrasocialty. The manifolds of the contempt network, differentially engaged across individuals and populations, explain the features of "contempt," its translatability, and its variable experience as "hot" or "cold," occurrent or enduring, and anger-like or disgust-like. This rapprochement between psychological anthropology and evolutionary psychology contributes both methodological and empirical insights, with broad implications for understanding the functional and cultural organization of social affect.

Seeing the elephant: Parsimony, functionalism, and the emergent design of contempt and other sentiments.

The target article argues that contempt is a sentiment, and that sentiments are the deep structure of social affect. The 26 commentaries meet these claims with a range of exciting extensions and applications, as well as critiques. Most significantly, we reply that construction and emergence are necessary for, not incompatible with, evolved design, while parsimony requires explanatory adequacy and predictive accuracy, not mere simplicity.

Moral parochialism and contextual contingency across seven societies.

Human moral judgement may have evolved to maximize the individual's welfare given parochial culturally constructed moral systems. If so, then moral condemnation should be more severe when transgressions are recent and local, and should be sensitive to the pronouncements of authority figures (who are often arbiters of moral norms), as the fitness pay-offs of moral disapproval will primarily derive from the ramifications of condemning actions that occur within the immediate social arena. Correspondingly, moral transgressions should be viewed as less objectionable if they occur in other places or times, or if local authorities deem them acceptable. These predictions contrast markedly with those derived from prevailing non-evolutionary perspectives on moral judgement. Both classes of theories predict purportedly species-typical patterns, yet to our knowledge, no study to date has investigated moral judgement across a diverse set of societies, including a range of small-scale communities that differ substantially from large highly urbanized nations. We tested these predictions in five small-scale societies and two large-scale societies, finding substantial evidence of moral parochialism and contextual contingency in adults' moral judgements. Results reveal an overarching pattern in which moral condemnation reflects a concern with immediate local considerations, a pattern consistent with a variety of evolutionary accounts of moral judgement.

Evolution after mirror neurons: tapping the shared manifold through secondary adaptation.

Cook et al. laudably call for careful comparative research into the development of mirror neurons. However, they do so within an impoverished evolutionary framework that does not clearly distinguish ultimate and proximate causes and their reciprocal relations. As a result, they overlook evidence for the reliable develop of mirror neurons in biological and cultural traits evolved to work through them.

The strategy of psychopathy: primary psychopathic traits predict defection on low-value relationships.

Recent evidence suggests that psychopathy is a trait continuum. This has unappreciated implications for understanding the selective advantage of psychopathic traits. Although clinical psychopathy is typically construed as a strategy of unconditional defection, subclinical psychopathy may promote strategic conditional defection, broadening the adaptive niche of psychopathy within human societies. To test this, we focus on a ubiquitous real-life source of conditional behaviour: the expected relational value of social partners, both in terms of their quality and the likely quantity of future interactions with them. We allow for conversational interaction among participants prior to their playing an unannounced, one-shot prisoner's dilemma game, which fosters naturalistic interpersonal evaluation and conditional behaviour, while controlling punishment and reputation effects. Individuals scoring higher on factor 1 (callous affect, interpersonal manipulation) of the Levenson self-report psychopathy scale defected conditionally on two kinds of low-value partners: those who interrupted them more during the conversation, and those with whom they failed to discover cues to future interaction. Both interaction effects support the hypothesis that subclinical primary psychopathy potentiates defection on those with low expected relational value. These data clarify the function and form of psychopathic traits, while highlighting adaptive variation in human social strategies.

Revenge without redundancy: functional outcomes do not require discrete adaptations for vengeance or forgiveness.

We question whether the postulated revenge and forgiveness systems constitute true adaptations. Revenge and forgiveness are the products of multiple motivational systems and capacities, many of which did not exclusively evolve to support deterrence. Anger is more aptly construed as an adaptation that organizes independent mechanisms to deter transgressors than as the mediator of a distinct revenge adaptation.

Preferences and constraints: the value of economic games for studying human behaviour.

As economic games have spread from experimental economics to other social sciences, so too have critiques of their usefulness for drawing inferences about the 'real world'. What these criticisms often miss is that games can be used to reveal individuals' private preferences in ways that observational and interview data cannot; furthermore, economic games can be designed such that they do provide insights into real-world behaviour. Here, we draw on our collective experience using economic games in field contexts to illustrate how researchers can strategically alter the framing or design of economic games to draw inferences about private-world or real-world preferences. A detailed case study from coastal Colombia provides an example of the subtleties of game design and how games can be combined fruitfully with self-report data. We close with a list of concrete recommendations for how to modify economic games to better match particular research questions and research contexts.

Body synchrony in triadic interaction.

Humans subtly synchronize body movement during face-to-face conversation. In this context, bodily synchrony has been linked to affiliation and social bonding, task success and comprehension, and potential conflict. Almost all studies of conversational synchrony involve dyads, and relatively less is known about the structure of synchrony in groups larger than two. We conducted an optic flow analysis of body movement in triads engaged in face-to-face conversation, and explored a common measure of synchrony: time-aligned bodily covariation. We correlated this measure of synchrony with a diverse set of covariates related to the outcome of interactions. Triads showed higher maximum cross-correlation relative to a surrogate baseline, and 'meta-synchrony', in that composite dyads in a triad tended to show correlated structure. A windowed analysis also revealed that synchrony varies widely across an interaction. As in prior studies, average synchrony was low but statistically reliable in just a few minutes of interaction. In an exploratory analysis, we investigated the potential function of body synchrony by predicting it from various covariates, such as linguistic style matching, liking, laughter and cooperative play in a behavioural economic game. Exploratory results do not reveal a clear function for synchrony, though colaughter within triads was associated with greater body synchrony, and is consistent with an earlier analysis showing a positive connection between colaughter and cooperation. We end by discussing the importance of expanding and codifying analyses of synchrony and assessing its function.

Community hygiene norm violators are consistently stigmatized: Evidence from four global sites and implications for sanitation interventions.

Community sanitation interventions increasingly leverage presumed innate human disgust emotions and desire for social acceptance to change hygiene norms. While often effective at reducing open defecation and encouraging handwashing, there are growing indications from ethnographic studies that this strategy might create collateral damage, such as reinforcing stigmatized identities in ways that can drive social or economic marginalization. To test fundamental ethnographic propositions regarding the connections between hygiene norm violations and stigmatized social identities, we conducted 267 interviews in four distinct global sites (in Guatemala, Fiji, New Zealand, USA) between May 2015 and March 2016. Based on 148 initial codes applied to 23,278 interview segments, text-based analyses show that stigmatizing labels and other indices of contempt readily and immediately attach to imagined hygiene violators in these diverse social settings. Moral concerns are much more salient at all sites than disease/contagion ones, and hygiene violators are extended little empathy. Contrary to statistical predictions, however, non-empathetic moral reactions to women hygiene violators are no harsher than those of male violators. This improved evidentiary base illuminates why disgust- and shame-based sanitation interventions can so easily create unintended social damage: hygiene norm violations and stigmatizing social devaluations are consistently cognitively connected.

General trust impedes perception of self-reported primary psychopathy in thin slices of social interaction.

Little is known about people's ability to detect subclinical psychopathy from others' quotidian social behavior, or about the correlates of variation in this ability. This study sought to address these questions using a thin slice personality judgment paradigm. We presented 108 undergraduate judges (70.4% female) with 1.5 minute video thin slices of zero-acquaintance triadic conversations among other undergraduates (targets: n = 105, 57.1% female). Judges completed self-report measures of general trust, caution, and empathy. Target individuals had completed the Levenson Self-Report Psychopathy (LSRP) scale. Judges viewed the videos in one of three conditions: complete audio, silent, or audio from which semantic content had been removed using low-pass filtering. Using a novel other-rating version of the LSRP, judges' ratings of targets' primary psychopathy levels were significantly positively associated with targets' self-reports, but only in the complete audio condition. Judge general trust and target LSRP interacted, such that judges higher in general trust made less accurate judgments with respect to targets higher in primary and total psychopathy. Results are consistent with a scenario in which psychopathic traits are maintained in human populations by negative frequency dependent selection operating through the costs of detecting psychopathy in others.

Men's physical strength moderates conceptualizations of prospective foes in two disparate societies.

Across taxa, strength and size are elementary determinants of relative fighting capacity; in species with complex behavioral repertoires, numerous additional factors also contribute. When many factors must be considered simultaneously, decision-making in agonistic contexts can be facilitated through the use of a summary representation. Size and strength may constitute the dimensions used to form such a representation, such that tactical advantages or liabilities influence the conceptualized size and muscularity of an antagonist. If so, and given the continued importance of physical strength in human male-male conflicts, a man's own strength will influence his conceptualization of the absolute size and strength of an opponent. In the research reported here, male participants' chest compression strength was compared with their estimates of the size and muscularity of an unfamiliar potential antagonist, presented either as a supporter of a rival sports team (Study 1, conducted in urban California, and Study 2, conducted in rural Fiji) or as a man armed with a handgun (Study 3, conducted in rural Fiji). Consistent with predictions, composite measures of male participants' estimates of the size/strength of a potential antagonist were inversely correlated with the participant's own strength. Therefore, consonant with a history wherein violent intrasexual selection has acted on human males, a man's own physical strength influences his representations of potential antagonists.

Subclinical primary psychopathy, but not physical formidability or attractiveness, predicts conversational dominance in a zero-acquaintance situation.

The determinants of conversational dominance are not well understood. We used videotaped triadic interactions among unacquainted same-sex American college students to test predictions drawn from the theoretical distinction between dominance and prestige as modes of human status competition. Specifically, we investigated the effects of physical formidability, facial attractiveness, social status, and self-reported subclinical psychopathy on quantitative (proportion of words produced), participatory (interruptions produced and sustained), and sequential (topic control) dominance. No measure of physical formidability or attractiveness was associated with any form of conversational dominance, suggesting that the characteristics of our study population or experimental frame may have moderated their role in dominance dynamics. Primary psychopathy was positively associated with quantitative dominance and (marginally) overall triad talkativeness, and negatively associated (in men) with affect word use, whereas secondary psychopathy was unrelated to conversational dominance. The two psychopathy factors had significant opposing effects on quantitative dominance in a multivariate model. These latter findings suggest that glibness in primary psychopathy may function to elicit exploitable information from others in a relationally mobile society.

Defectors cannot be detected during"small talk" with strangers.

To account for the widespread human tendency to cooperate in one-shot social dilemmas, some theorists have proposed that cooperators can be reliably detected based on ethological displays that are difficult to fake. Experimental findings have supported the view that cooperators can be distinguished from defectors based on "thin slices" of behavior, but the relevant cues have remained elusive, and the role of the judge's perspective remains unclear. In this study, we followed triadic conversations among unacquainted same-sex college students with unannounced dyadic one-shot prisoner's dilemmas, and asked participants to guess the PD decisions made toward them and among the other two participants. Two other sets of participants guessed the PD decisions after viewing videotape of the conversations, either with foreknowledge (informed), or without foreknowledge (naïve), of the post-conversation PD. Only naïve video viewers approached better-than-chance prediction accuracy, and they were significantly accurate at predicting the PD decisions of only opposite-sexed conversation participants. Four ethological displays recently proposed to cue defection in one-shot social dilemmas (arms crossed, lean back, hand touch, and face touch) failed to predict either actual defection or guesses of defection by any category of observer. Our results cast doubt on the role of "greenbeard" signals in the evolution of human prosociality, although they suggest that eavesdropping may be more informative about others' cooperative propensities than direct interaction.