As humans, several non-human animal species avoid risk, defined as "variability in rate of gain". However, non-human primate studies revealed a more complicated picture, with different species ranging from risk aversion to risk proneness. Within an ecological rationality framework, a species' feeding ecology should influence its risk preferences, as it has been shown in bonobos and chimpanzees. Although the feeding ecology hypothesis is promising, it has not been yet verified in species other than apes. Here, we aimed to assess whether this hypothesis holds true in tufted capuchin monkeys (Sapajus spp.). Ten capuchins were presented with choices between a "safe" option and a "risky" option in three conditions differing for the probability of receiving the larger reward when selecting the risky option. Similarly to chimpanzees, capuchins were risk prone. However, capuchins' behaviour was not the result of a bias towards the choice of the risky option, since-when facing options with different probabilities of obtaining the larger outcome-they were able to flexibly modify their preferences. Capuchins' decision-making under risk mirrors their risk-prone behaviour in the wild, where they often rely on unpredictable and/or hazardous food sources, thus satisfying the feeding ecology hypothesis.

Recent studies have shown that sympathetic nervous system (SNS) activity can be heavily impacted not only by basic threats to survival but also by threats to social bonds. In this study we explored the behavioral and physiological consequences of social exclusion/inclusion in patients with psoriasis, a disease frequently associated with the experience of being ostracized and with deficient emotion regulation skills. We employed a virtual ball-tossing game (Cyberball) to induce the experience of social exclusion/inclusion. We then used a Trust Game to measure the effects of this social modulation on trust. During Cyberball, infrared thermal imaging was used to record participants’ facial temperature and thus obtain an online measure of SNS activation. Behavioral data showed that social exclusion shifted participants’ trust toward unfamiliar players who had not previously excluded them. Physiological data indicated that in control participants, social exclusion triggered higher SNS activation than inclusion. No such effect was found in patients with psoriasis, whose SNS activity was the same during inclusion as it was during exclusion, suggesting that they benefit less from inclusive experiences than control participants. In addition, in patients but not in controls, higher SNS activation during social exclusion was linked to higher monetary investment toward unfamiliar players, a result in keeping with the social reconnection hypothesis, according to which emotions triggered by social rejection can be regulated by investing in new social interactions. We also found that an increase in periorbital temperature is accompanied by a decrease in happiness ratings after social exclusion was experienced during the Cyberball game. NEW & NOTEWORTHY Previous research on emotional processes in psoriasis has mainly employed self-report measures. In this study we used thermal imaging to obtain an online measure of the sympathetic nervous system (SNS) activity during social exclusion and tested how this experience influenced subsequent trust. We found that being included was a less positive experience for patients compared with controls and that SNS activity during exclusion had a stronger influence on subsequent trust in patients than in controls.