Sex differences and action scaling in overhead reaching.

Specifications of affordances is independent of the anthropometric scale of the perceiver. It is therefore predicted that sex differences disappear when perceptual performance is scaled relative to the relevant physical properties of the system formed by performer and environment in a particular action. 24 women and 30 men were compared for their ability to perceive the boundaries for overhead reaching for a ball suspended above them. Perceived and actual maximum action boundaries were measured in two height conditions, with and without wearing 15-cm high blocks under their feet. On average the men reached higher than the women; however, when perceived maximum reachable height was expressed as a ratio of actual maximum reachable height, the difference between the groups disappeared. The participants showed an identical fit between environment and performer in both height conditions. The results indicate that the specification of affordances for overhead reaching is independent of the height and the sex of the performer.