Sex differences in in-group cooperation vary dynamically with competitive conditions and outcomes

Men's but not women's investment in a public goods game varied dynamically with the presence or absence of a perceived out-group. Three hundred fifty-four (167 male) young adults participated in multiple iterations of a public goods game under intergroup and individual competition conditions. Participants received feedback about whether their investments in the group were sufficient to earn a bonus to be shared among all in-group members. Results for the first trial confirm previous research in which men's but not women's investments were higher when there was a competing out-group. We extended these findings by showing that men's investment in the in-group varied dynamically by condition depending on the outcome of the previous trial: In the group condition, men, but not women, decreased spending following a win (i.e., earning an in-group bonus). In the individual condition, men, but not women, increased spending following a win. We hypothesize that these patterns reflect a male bias to calibrate their level of in-group investment such that they sacrifice only what is necessary for their group to successfully compete against a rival group.     

Rapid cognitive flexibility of rhesus macaques performing psychophysical task-switching

Three rhesus monkeys (Macaca mulatta) performed a simultaneous chaining task in which stimuli had to be sorted according to their visual properties. Each stimulus could vary independently along two dimensions (luminosity and radius), and a cue indicating which dimension to sort by was random trial to trial. These rapid and unpredictable changes constitute a task-switching paradigm, in which subjects must encode task demands and shift to whichever task-set is presently activated. In contrast to the widely reported task-switching delay observed in human studies, our subjects show no appreciable reduction in reaction times following a switch in the task requirements. Also, in contrast to the results of studies on human subjects, monkeys experienced enduring interference from trial-irrelevant stimulus features, even after exhaustive training. These results are consistent with a small but growing body of evidence that task-switching in rhesus macaques differs in basic ways from the pattern of behavior reported in studies of human cognition. Given the importance of task-switching paradigms in cognitive and clinical assessment, and the frequency with which corresponding animal models rely on non-human primates, understanding these differences in behavior is essential to the comparative study of cognitive impairment.     

Personality diagnosis with the Shedler-Westen Assessment Procedure (SWAP): integrating clinical and statistical measurement and prediction

This article describes the Shedler-Westen Assessment Procedure (SWAP), a personality assessment instrument intended for use by clinically experienced interviewers, designed to maximize both psychometric precision and clinical relevance. The article focuses on the latest edition of the instrument, the SWAP-II; its use in 2 recently completed large-sample projects; and the ways in which data from these projects are being used to revise and refine concepts of personality pathology and taxonomy. The article first details the development of the SWAP and its psychometric rationale. It then examines the use of SWAP data for purposes of (a) improving diagnostic criteria within the framework of the existing Diagnostic and Statistical Manual of Mental Disorders taxonomy, (b) developing a new classification of personality pathology based on empirically identified diagnostic groupings, and (c) identifying trait dimensions relevant to understanding personality syndromes and disorders. Finally, the article discusses future research directions and challenges.