Sex Differences in Infants' Mapping of Complex Occlusion Sequences: Further Evidence

Recently, infant researchers have reported sex differences in infants' capacity to map their representation of an occlusion sequence onto a subsequent no‐occlusion display. The research reported here sought to identify the extent to which these sex differences are observed in event‐mapping tasks and to identify the underlying basis for these differences. Two experiments were conducted with 9.5‐, 10.5‐, and 11.5‐month‐olds using the following task. First, infants were shown an occlusion event in which a box and a ball emerged successively to opposite sides of a screen. Then, the screen was lowered and infants saw a single ball on the platform. Boys first showed prolonged looking to the 1‐ball display at 10.5 months, suggesting that at 10.5 months, boys detected the inconsistency between the box‐ball occlusion sequence and the final 1‐ball display. In contrast, girls first showed prolonged looking to the 1‐ball display at 11.5 months. However, girls did show prolonged looking at 10.5 months if they were shown an outline of the box‐ball occlusion sequence prior to the test trials. These results provide converging evidence for the conclusion that boys are more likely than girls to successfully map complex occlusion sequences onto no‐occlusion displays. These results also suggest that boys perform better on event‐mapping tasks because they are more adept at extracting the simple structure of complex occlusion sequences that they can then retrieve and compare to the final display, but that girls can extract the simple structure under more supportive conditions. Possible reasons for these robust, albeit transient, sex differences are suggested.