Sex categorization among preschool children: increasing utilization of sexually dimorphic cues.

Two studies examined how children between ages 4 and 6 use body shape (i.e., the waist-to-hip-ratio [WHR]) for sex categorization. In Study 1 (N=73), 5- and 6-year-olds, but not 4-year-olds, selected bodies with increasingly discrepant WHRs to be "most like a man" and "most like a woman." Similarly, sex category judgments made by 5- and 6-year-olds, but not 4-year-olds, varied with WHR. In Study 2 (N=41), eye movements indicated the functional use of waist and hips in sex categorization. Visual scanning behavior predicted the degree of association between WHR and judgment. Collectively, these results suggest that the ability to exploit sexual dimorphism to compel categorization develops between the ages of 4 and 6. Implications for theories of gender development and psychological essentialism are discussed.