a b s t r a c tInterest in sex-related differences in psychological functioning has again come to the foreground with new findings about their possible functional basis in the brain. Sex differences may be one way how evolution has capitalized on the capacity of homologous brain regions to process social information between men and women differently. This paper focuses specifically on the effects of emotional valence, sex of the observed and sex of the observer on regional brain activations. We also discuss the effects of and interactions between environment, hormones, genes and structural differences of the brain in the context of differential brain activity patterns between men and women following exposure to seen expressions of emotion and in this context we outline a number of methodological considerations for future research. Importantly, results show that although women are better at recognizing emotions and express themselves more easily, men show greater responses to threatening cues (dominant, violent or aggressive) and this may reflect different behavioral response tendencies between men and women as well as evolutionary effects. We conclude that sex differences must not be ignored in affective research and more specifically in affective neuroscience.

During social interactions, people tend to automatically align with, or mimic their interactor's facial expressions, vocalizations, postures and other bodily states. Automatic mimicry might be implicated in empathy and affiliation and is impaired in several pathologies. Despite a growing body of literature on its phenomenology, the function and underlying mechanisms of mimicry remain poorly understood. The current review puts forward a new Neurocognitive Model of Emotional Contagion (NMEC), demonstrating how basic automatic mimicry can give rise to emotional contagion. We combine neurological, developmental and evolutionary insights to argue that automatic mimicry is a precursor to healthy social development. We show that (i) strong synchronization exists between people, (ii) that this resonates on different levels of processing and (iii) demonstrate how mimicry translates into emotional contagion. We conclude that our synthesized model, built upon integrative knowledge from various fields, provides a promising avenue for future research investigating the role of mimicry in human mental health and social development.

In humans, the hypothalamic neuropeptide oxytocin shifts the individual’s focus on self-interest toward group-serving cognitions and decision-making. Here we examine this general tendency in the context of group formation, where individuals included into their group (or not) 18 targets morphed as having low or high-threat potential (with high-threat targets being beneficial to group-interests but potentially hurting the recruiter’s self-interest). Ninety healthy males self-administered oxytocin or placebo in a randomized double-blind, placebo-controlled study design, had their hands scanned to derive fetal testosterone vs. estradiol exposure from their 2D:4D ratio, and self-reported on their chronic empathic concern. Multilevel regression models revealed that when given oxytocin rather than placebo, individuals with low fetal testosterone priming included low-threat targets more and high-threat targets (somewhat) less. Individuals with high fetal testosterone (i.e., low estradiol) exposure, however, included high-threat targets more, and low-threat targets less when given oxytocin rather than placebo. Second, when given oxytocin rather than placebo, individuals with low empathic concern included low-threat targets more and high-threat targets less. Individuals with high empathic concern, however, included high-threat targets more, and low-threat targets less when given oxytocin rather than placebo. We conclude that oxytocin shifts the individual’s focus from self to group-serving cognition and decision-making, and that these tendencies are stronger for males with high rather than low fetal testosterone vs. estradiol exposure, and high rather than low empathic concern. Implications and avenues for future research are discussed.

During close interactions with fellow group members, humans look into one another’s eyes, follow gaze, and quickly grasp emotion signals. The eye-catching morphology of human eyes, with unique eye whites, draws attention to the middle part, to the pupils, and their autonomic changes, which signal arousal, cognitive load, and interest (including social interest). Here, we examined whether and how these changes in a partner’s pupils are processed and how they affect the partner’s trustworthiness. Participants played incentivized trust games with virtual partners, whose pupils dilated, remained static, or constricted. Results showed that (a) participants trusted partners with dilating pupils and withheld trust from partners with constricting pupils, (b) participants’ pupils mimicked changes in their partners’ pupils, and (c) dilation mimicry predicted trust in in-group partners, whereas constriction mimicry did not. We suggest that pupil-contingent trust is in-group bounded and possibly evolved in and because of group life.

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