All together now
Something to talk about: Are conversation sizes constrained by mental modeling abilities?
Jaimie Arona Krems, Robin Dunbar & Steven Neuberg
Evolution and Human Behavior, forthcoming
Abstract:
Conversations are ubiquitous and central elements of daily life. Yet a fundamental feature of conversation remains a mystery: It is genuinely difficult to maintain an everyday conversation with more than four speakers. Why? We introduce a “mentalizing explanation” for the conversation size constraint, which suggests that humans have a natural limit on their ability to model the minds of others, and that this limit, in turn, shapes the sizes of everyday conversations. Using established methodologies for investigating conversation size, we pit this mentalizing hypothesis against two competing explanations — that the size of a conversation is limited by a short-term memory capacity (limiting the factual information we process) or by an auditory constraint (speakers need to be able to hear what each other are saying) — in conversations drawn from a real-world college campus and from Shakespearean plays. Our results provide support for the mentalizing hypothesis and also render alternative accounts less plausible.
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Neural and Behavioral Evidence for Infants' Sensitivity to the Trustworthiness of Faces
Sarah Jessen & Tobias Grossmann
Journal of Cognitive Neuroscience, forthcoming
Abstract:
Face evaluation is a key aspect of face processing in humans, serving important functions in regulating social interactions. Adults and preschool children readily evaluate faces with respect to a person's trustworthiness and dominance. However, it is unclear whether face evaluation is mainly a product of extensive learning or a foundational building block of face perception already during infancy. We examined infants' sensitivity to facial signs of trustworthiness (Experiment 1) and dominance (Experiment 2) by measuring ERPs and looking behavior in response to faces that varied with respect to the two facial attributes. Results revealed that 7-month-old infants are sensitive to facial signs of trustworthiness but not dominance. This sensitivity was reflected in infants' behavioral preference and in the modulation of brain responses previously linked to the emotion detection from faces. These findings provide first evidence that processing faces with respect to trustworthiness has its origins in infancy and shed light on the behavioral and neural correlates of early emerging sensitivity.
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Visual attention to powerful postures: People avert their gaze from nonverbal dominance displays
Elise Holland et al.
Journal of Experimental Social Psychology, forthcoming
Abstract:
This paper investigates whether humans avert their gaze from individuals engaging in nonverbal displays of dominance. Although past studies demonstrate that both humans and nonhuman primates direct more visual attention to high-status others than low-status others, non-human primates avert their gaze when high-status conspecifics engage in nonverbal dominance displays (e.g., chest pounding). In two experiments, participants were eye-tracked while viewing photographs of men and women adopting either dominant, high-power (i.e., expansive and open) or submissive, low-power (i.e., contractive and closed) nonverbal postures. Results demonstrated that humans, like primates, avert their gaze from the faces and upper bodies of individuals displaying dominance compared to those displaying submissiveness. Not only did participants look less often at the faces and upper bodies of dominance-displaying individuals, they also fixated on these regions for shorter durations. Our findings ultimately suggest that nonverbal dominance displays influence humans' visual attention in ways that are likely to shape how social interactions unfold.
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Epigenetic modification of OXT and human sociability
Brian Haas et al.
Proceedings of the National Academy of Sciences, 5 July 2016, Pages E3816–E3823
Abstract:
Across many mammalian species there exist genetic and biological systems that facilitate the tendency to be social. Oxytocin is a neuropeptide involved in social-approach behaviors in humans and others mammals. Although there exists a large, mounting body of evidence showing that oxytocin signaling genes are associated with human sociability, very little is currently known regarding the way the structural gene for oxytocin (OXT) confers individual differences in human sociability. In this study, we undertook a comprehensive approach to investigate the association between epigenetic modification of OXT via DNA methylation, and overt measures of social processing, including self-report, behavior, and brain function and structure. Genetic data were collected via saliva samples and analyzed to target and quantify DNA methylation across the promoter region of OXT. We observed a consistent pattern of results across sociability measures. People that exhibit lower OXT DNA methylation (presumably linked to higher OXT expression) display more secure attachment styles, improved ability to recognize emotional facial expressions, greater superior temporal sulcus activity during two social-cognitive functional MRI tasks, and larger fusiform gyrus gray matter volume than people that exhibit higher OXT DNA methylation. These findings provide empirical evidence that epigenetic modification of OXT is linked to several overt measures of sociability in humans and serve to advance progress in translational social neuroscience research toward a better understanding of the evolutionary and genetic basis of normal and abnormal human sociability.
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Damian Murray et al.
Evolution and Human Behavior, forthcoming
Abstract:
The direct adaptive impact of rituals and other forms of behavior dictated or shaped by culture may be one factor influencing their persistence or lack thereof over time. Given that physical contact is a common means through which transmissible disease is spread, we explored the possibility that levels of normative physical contact would be negatively associated with levels of infectious disease prevalence. We tested this prediction across three domains of such behavior — greetings, romantic kissing, and mortuary rituals — by compiling ethnographic information on normative behavior in traditional cultures and comparing it with epidemiological estimates of pathogen prevalence. We find small but significant negative correlations between pathogen prevalence and both greetings and romantic kissing. Ancillary analyses suggest that these relationships are driven by human-transmitted pathogens. The relationship between pathogen prevalence and mortuary rituals is non-significant. Causal mechanisms that may account for these results, as well as implications and limitations, are discussed.
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Sylvie Bernaerts et al.
Psychoneuroendocrinology, forthcoming
Abstract:
The neuropeptide ‘oxytocin’ (OT) is known to play a pivotal role in a variety of complex social behaviors by promoting a prosocial attitude and interpersonal bonding. One mechanism by which OT is hypothesized to promote prosocial behavior is by enhancing the processing of socially relevant information from the environment. With the present study, we explored to what extent OT can alter the ‘reading’ of emotional body language as presented by impoverished biological motion point light displays (PLDs). To do so, a double-blind between-subjects randomized placebo-controlled trial was conducted, assessing performance on a bodily emotion recognition task in healthy adult males before and after a single-dose of intranasal OT (24 IU). Overall, a single-dose of OT administration had a significant effect of medium size on emotion recognition from body language. OT-induced improvements in emotion recognition were not differentially modulated by the emotional valence of the presented stimuli (positive versus negative) and also, the overall tendency to label an observed emotional state as ‘happy’ (positive) or ‘angry’ (negative) was not modified by the administration of OT. Albeit moderate, the present findings of OT-induced improvements in bodily emotion recognition from whole-body PLD provide further support for a link between OT and the processing of socio-communicative cues originating from the body of others.
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Are you looking my way? Ostracism widens the cone of gaze
Pessi Lyyra, James Wirth & Jari Hietanen Quarterly
Journal of Experimental Psychology, forthcoming
Abstract:
Ostracized individuals demonstrate an increased need for belonging. To satisfy this need, they search for signals of inclusion, one of which may be another person’s gaze directed at oneself. We tested if ostracized, compared to included, individuals judge a greater degree of averted gaze as still being direct. This range of gaze angles still viewed as direct has been dubbed “the cone of (direct) gaze”. In the current research, ostracized and included participants viewed friendly-looking face stimuli with direct or slightly averted gaze (0°, 2°, 4°, 6°, and 8° to the left and to the right) and judged whether stimulus persons were looking at them or not. Ostracized individuals demonstrated a wider gaze cone than included individuals.
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Oxytocin, the peptide that bonds the sexes also divides them
Shan Gao et al.
Proceedings of the National Academy of Sciences, 5 July 2016, Pages 7650–7654
Abstract:
Facilitation of social attraction and bonding by the evolutionarily conserved neuropeptide oxytocin is well-established in female mammals. However, accumulating behavioral evidence suggests that oxytocin may have evolved sex-specific functional roles in the domain of human social cognition. A critical question is how oxytocin differentially modulates neural processing of social information in men and women, leading to divergent behavioral responses. Here we show that intranasal oxytocin treatment produces sex- and valence-dependent increases in amygdala activation when women view individuals identified as praising others but in men those who criticize them. Women subsequently show increased liking for the faces of these individuals, whereas in men it is reduced. Thus, oxytocin may act differentially via the amygdala to enhance the salience of positive social attributes in women but negative ones in men. We hypothesize that oxytocin may have evolved different but complementary roles to help ensure successful reproduction by encouraging mothers to promote a prosocial rearing environment for offspring and fathers to protect against antisocial influences.