Categorical perception of facial gender information: Behavioural evidence and the face-space metaphor

Categorization is a fundamental property of the human brain. We used an ima ge-morphing procedure to investigate the categorical perception of facial g ender information. Three experiments, an identification and two matching ta sks, were reported. First, we showed that, even when facial image informati on changes linearly across unfamiliar male and female faces, gender is perc eived categorically. This holds only when faces are presented in an upright orientation. Second, subjects discriminated more easily two unknown morphe d faces presenting a gender change as compared to two unknown morphed faces belonging to the same gender, even when the physical distance between the pairs was identical. We discuss the results in terms of how representations of faces are encoded and stored in long-term memory.