The type of implicit motive enactment is modulated by sex hormones in naturally cycling women.

Sex hormones have been reported to dynamically modulate the expression of implicit motives, a concept that has previously been thought to be relatively stable over time. This study investigates to what extent the need for affiliation, power, and achievement, as well as the form of enactment of these needs as measured with the Operant Motive Test (OMT), is affected by cycle-phase dependent sex hormone fluctuations. In addition to measuring the strength of motive expression, the OMT also captures different forms of motive enactment. In an intra-subject design with repeated measures, no evidence for cycle-phase related variation in overall motive scores was found. However, when different forms of motive enactment were considered, an effect of menstrual cycle was observed. The incentive-based inhibition of the power motive was significantly reduced at the time of ovulation, compared to the menstrual and to the mid-luteal phase, in naturally cycling women. In women with relatively stable hormone concentrations (due to using hormonal contraceptives), no significant changes in the form of motive enactment were evident. The results indicate a specific hormonal influence on motive-related cognitive processes that are related to inhibitive processes in behavior control.

Multisensory integration across the menstrual cycle.

Evidence suggests that spatial processing changes across time in naturally cycling women, which is likely due to neuromodulatory effects of steroid hormones. Yet, it is unknown whether crossmodal spatial processes depend on steroid hormones as well. In the present experiment, the crossmodal congruency task was used to assess visuo-tactile interactions in naturally cycling women, women using hormonal contraceptives and men. Participants adopted either a crossed or uncrossed hands posture. It was tested whether a postural effect of hand crossing on multisensory interactions in the crossmodal congruency task is modulated by women's cycle phase. We found that visuotactile interactions changed according to cycle phase. Naturally cycling women showed a significant difference between the menstrual and the luteal phase for crossed, but not for uncrossed hands postures. The two control groups showed no test sessions effects. Regression analysis revealed a positive relation between estradiol levels and the size of crossmodal congruency effects (CCE), indicating that estradiol seems to have a neuromodulatory effect on posture processing.

Variability in ratings of trustworthiness across the menstrual cycle.

This study investigated how trusting behavior varies in naturally cycling women, as a function of sex and attractiveness of players in a trust game, at three distinct phases of the menstrual cycle. Women acted more cautiously in an investment game at the preovulatory phase, compared to the menstrual and the mid-luteal phase. Reduced willingness to trust in strangers was particularly expressed toward male players at this time. The increase of estradiol levels from menses to the preovulatory phase was negatively correlated with trust in attractive male other players, whereas the increase of progesterone levels from menses to the mid-luteal phase was positively associated with trust in unattractive female other players. No particular contribution of a single hormone level could be identified for the generally reduced willingness to trust in strangers in the preovulatory phase. Thus, the results emphasize the impact of the menstrual cycle on interpersonal trust, although the exact mode of hormonal action needs to be further investigated.

Visuotactile interactions in the congenitally acallosal brain: evidence for early cerebral plasticity.

Studies in patients with an isolated, congenital agenesis of the corpus callosum have documented potentials and limits of brain plasticity. Literature suggests that early reorganization mechanisms can compensate for the absence of the corpus callosum in unisensory tasks that involve interhemispheric transfer. It is unknown, however, how the congenitally acallosal brain processes multisensory information, which presumably requires interhemispheric transfer of modality-specific input. Therefore, we tested five patients with total and one patient with partial agenesis of the corpus callosum in a visuotactile interference task (the "crossmodal congruency task") with uncrossed and crossed hands and compared their performance to that of 31 healthy controls. We found that congruency effects followed the hands in space not only in healthy, but also in congenitally acallosal individuals. Remarkably, this was also true when patients' hands crossed the vertical visual meridian and stimuli were presented at the same hand. These results suggest that callosal connectivity is not required for remapping of visuotactile space. We conclude that early brain plasticity allows for compensation of the developmental absence of the corpus callosum in a visuotactile interference task.

Sex differences in parking are affected by biological and social factors.

The stereotype of women's limited parking skills is deeply anchored in modern culture. Although laboratory tests prove men's average superiority in visuospatial tasks and parking requires complex, spatial skills, underlying mechanisms remain unexplored. Here, we investigated performance of beginners (nine women, eight men) and more experienced drivers (21 women, 27 men) at different parking manoeuvres. Furthermore, subjects conducted the mental rotation test and self-assessed their parking skills. We show that men park more accurately and especially faster than women. Performance is related to mental rotation skills and self-assessment in beginners, but only to self-assessment in more experienced drivers. We assume that, due to differential feedback, self-assessment incrementally replaces the controlling influence of mental rotation, as parking is trained with increasing experience. Results suggest that sex differences in spatial cognition persist in real-life situations, but that socio-psychological factors modulate the biological causes of sex differences.