Infants' identification of gender in biological motion displays

Development and validation of the Interoceptive States Vocalisations (ISV) and Interoceptive States Point Light Displays (ISPLD) databases

The ability to perceive others' emotions and one's own interoceptive states has been the subject of extensive research. Very little work, however, has investigated the ability to recognise others' interoceptive states, such as whether an individual is feeling breathless, nauseated, or fatigued. This is likely owing to the dearth of stimuli available for use in research studies, despite the clear relevance of this ability to social interaction and effective caregiving. This paper describes the development and validation of two stimulus sets for use in research into the perception of others' interoceptive states. The Interoceptive States Vocalisations (ISV) database and the Interoceptive States Point Light Displays (ISPLD) database include 191 vocalisation and 159 point light display stimuli. Both stimulus sets underwent two phases of validation, and all stimuli were scored in terms of their quality and recognisability, using five different measures. The ISV also includes control stimuli featuring non-interoceptive vocalisations. Some interoceptive states were consistently recognised better than others, but variability was observed within, as well as between, stimulus categories. Stimuli are freely available for use in research, and are presented alongside all stimulus quality scores, in order for researchers to select the most appropriate stimuli based on individual research questions.

Recognition of humans from biological motion in infants

Infant studies have suggested that the detection of biological motion (BM) might be an innate capacity, based on newborns' spontaneous preference for BM. However, it is unclear if, like adults, infants recognize humans from BM and are able to build the representation of bodies and faces. To address this issue, we tested whether exposure to BM influences subsequent face recognition in 3- to 8-month-old infants. After familiarization with a point-light walker (PLW) of either a female or a male, the infant's preference for female and male faces was measured. If infants can build the representation of not only the body but also the face from PLWs, the familiarization effect of gender induced by the PLW might be generalized to faces. We found that infants at 7 to 8 months looked for longer at the face whose gender was opposite to that of the PLW, whereas 3- to 4- and 5- to 6-month-old infants did not. These results suggest that infants can access the representation of humans from BM and extract gender, which is shared across bodies and faces, from at least 7 to 8 months of age.

Sex Differences in Competitiveness in Massively Multiplayer Online Role-Playing Games (MMORPGs)

Sex differences in the use of competitive tactics have been well established. Although many factors may contribute to these sex differences, according to social role theory (SRT), stereotypes and expectations about men's and women's typical social roles are crucial. We addressed the potential impact of social roles by studying massively multiplayer online role-playing games (MMORPGs), a setting where individuals represent themselves with avatars and thus enjoy the opportunity to compete without regard to the typical expectations and behaviors associated with men's and women's roles. We surveyed players via MTurk (63 women, 191 men) and Reddit (166 women, 1,326 men) regarding their frequency of engaging in five competitive behaviors and the sex and role of their primary avatar. As expected, there were reliable sex differences in competitiveness: men were more likely than women to engage in player-versus-player duels (MTurk d = 0.19; Reddit d = 0.51), do solo runs of difficult content (0.30, 0.35), and work to acquire expensive items (0.32, 0.19); women were more likely than men to seek in-game awards (-0.38, -0.36) and spend real-world money on expensive microtransactions (-0.16, -0.27). Contrary to SRT, these sex differences in forms of competitive behavior were generally unrelated to players' chosen avatar sex or avatar role. These results instead indicate that sex differences in competitiveness largely reflect evolved predispositions.