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- PublicationMétadonnées seulementGroup Membership Affects Spontaneous Mental Representation: Failure to Represent the Out-Group in a Joint Action Task(2014-1-28)Predicting others’ actions is crucial to successful social interaction. Previous research on joint action, based on a reaction-time paradigm called the Joint Simon Task, suggests that successful joint action stems from the simultaneous representation of the self with the other. Performance on this task provides a read-out of the degree of intrusion from a partner that participants experience from acting jointly compared to acting alone, which in turn is a measure of the degree to which participants mentally represent their co-actors during the task. To investigate the role of perceived group membership in this type of joint action and its influence on the representation of others, we first subjected participants to a minimal group paradigm while manipulating differences in social competition. We then asked participants to do the Joint Simon Task in pairs with an in-group or out-group member. Only participants who acted with an “in-group” partner on the joint task showed altered reaction times compared to when acting alone, presumably a change caused by the simultaneous and automatic representation of their in-group partner. In contrast, participants who acted with an out-group partner were unaffected in their reactions when doing the joint task, showing no evidence of representation of their out-group partner. This effect was present in both the high-competition and low-competition conditions, indicating that the differential effects of group membership on representation during joint action were driven by perceived group membership and independent of the effects of social competition. We concluded that participants failed to represent out-group members as socially relevant agents not based on any personality or situational characteristics, but in reaction only to their status as “other”. In this way group membership appears to affect cognition on a very immediate and subconscious level.
- PublicationMétadonnées seulementScent marking by male mice under the risk of predation(2001-1-28)The use by predators of scent marks made by potential prey is a largely unexplored potential cost of olfactory signaling. Here we investigate how animals that differ in their investment in scent-marking respond to simulated predation risk, by comparing the willingness to approach and counter-mark the scent marks of a competitor in the presence or absence of predator odor. We aimed to test whether animals that invest heavily in scent-marking, and which may thus be more vulnerable to eavesdropping predators, will either (1) take greater risks to counter-mark the competitor's scent or (2) reduce or abandon scent-marking. Using outbred male laboratory mice, Mus musculus, we show that, in the absence of predators, individuals which initially scent-mark at high frequency (high markers) approach the competitor's scent marks more quickly and spend more time in counter-marking than those which initially invest relatively little (low markers). In a sib-sib experimental design, simulated presence of predation risk (urine of ferrets, Mustela putorius furo) caused both kinds of individual to approach the competitor's marks more slowly, but high markers approached more quickly than low markers and spent more time in the vicinity of the competitor's marks. Only high markers significantly reduced their overmarking of the competitor's scent. These results suggest (1) that there is a unique danger inherent to scent-marking at high frequencies and (2) that high-marking males were prepared to accept increased costs of intrasexual competition in order to reduce the risk of predation. Further tests using the scent of naked mole-rats, Heterocephalus glaber, showed that these effects were not elicited simply by an unfamiliar odor. We discuss reasons for the observed difference in response to predation risk between the groups, and the implications of these results for counter-selection on scent-marking strategies.
- PublicationMétadonnées seulementEndogenous oxytocin predicts helping and conversation as a function of group membership(2018-7-4)
; ; ; ;Humans cooperate with unrelated individuals to an extent that far outstrips any other species. We also display extreme variation in decisions about whether to cooperate or not, and the mechanisms driving this variation remain an open question across the behavioural sciences. One candidate mechanism underlying this variation in cooperation is the evolutionary ancient neurohormone oxytocin (OT). As current research focuses on artificial administration of OT in asocial tasks, little is known about how the hormone in its naturally occurring state actually impacts behaviour in social interactions. Using a new optimal foraging paradigm, the ‘egg hunt’, we assessed the association of endogenous OT with helping behaviour and conversation. We manipulated players' group membership relative to each other prior to an egg hunt, during which they had repeated opportunities to spontaneously help each other. Results show that endogenous baseline OT predicted helping and conversation type, but crucially as a function of group membership. Higher baseline OT predicted increased helping but only between in-group players, as well as decreased discussion about individuals’ goals between in-group players but conversely more of such discussion between out-group players. Subsequently, behaviour but not conversation during the hunt predicted change in OT, in that out-group members who did not help showed a decrease in OT from baseline levels. In sum, endogenous OT predicts helping behaviour and conversation, importantly as a function of group membership, and this effect occurs in parallel to uniquely human cognitive processes.