We used silhouettes of headless human bodies, devoid of primary sexual characteristics but possessing enough morphological information to visually convey the sexual phenotype, as stimuli of a visual adaptation paradigm. The results show that prolonged adaptation to a distinctively male or female body induces a gender-specific contrast aftereffect on the subsequent perception of a neutral (androgynous) body (i.e., after exposure to a female body, the androgynous body appears as more male). This is the first demonstration that adaptation occurs for the sexually dimorphic global shape of the human body, thus proving that bodily gender can be listed as a dimension sensitive to visual adaptation, similarly to faces. Intriguingly, the contrast aftereffects measured were much stronger following exposure to adapters of the same gender as the observers', possibly suggesting a role of perceptual experience favouring mate selection and pair bonding.
In a previous study, we found that when required to imagine another person performing an action, participants reported a higher correspondence between their own handedness and the hand used by the imagined person when the agent was seen from the back compared to when the agent was seen from the front. This result was explained as evidence of a greater involvement of motor areas in the back-view perspective, possibly indicating a greater proneness to put oneself in the agent's shoes in such a condition. In turn, the proneness to put oneself in another's shoes could also be considered as a cue of greater identification with the other, that is a form of empathy. If this is the case, the proportion of lateral matches vs mismatches should be different for subjects with high and low self-reported empathy. In the present study, we aimed at testing this hypothesis. Participants were required to imagine a person performing a single manual action in a back view and to indicate the hand used by the imagined person during movement execution. Consistent with our hypothesis, the proportion of matching between the handedness of participants and the handedness of agents imagined was higher for participants scoring high in a self-report measure of empathy. Importantly, this relationship was specific for females. At least for females, our data seem to corroborate the idea of a link between self-reported empathy and motor identification with imagined agents. This sex-specific result is consistent with neuroimaging studies indicating a stronger involvement of action representations during emotional and empathic processing in females than in males. In sum, our findings underline the possibility of employing behavioral research as a test-bed for theories deriving from functional studies suggesting a link between empathic processing and the activation of motor-related areas.