Sex Differences in the Recognition of Children's Emotional Expressions: A Test of the Fitness Threat Hypothesis

Evolutionary theories have suggested that a female superiority in the recognition of facial emotion may be an adaptation that arises from women's greater responsibility and investment in child-rearing and infant care. In a previous study, we showed a female superiority on a set of computer-administered emotion recognition tasks that was most prominent for the discrimination of negatively as opposed to positively valenced facial expressions (e.g., fear), providing empirical support for the "fitness threat" hypothesis. In the present study, we further investigated sex differences in a new sample of 95 healthy men and women of reproductive age (M-age = 22.09 years), using images of both children's and adult's faces as stimuli to evaluate the speed and accuracy of emotion recognition. A female superiority in accuracy, which was more pronounced for negative than positive expressions, was found for adult face stimuli, replicating our previous findings. The sex difference was shown to extend robustly to infant and toddler faces, which represent a more ecologically valid test of the fitness threat hypothesis. Direct parenting experience, but not other forms of learned experience involving young children, was also found to be associated with the accuracy of emotion discrimination. Implications of this association are discussed.