The classification of 'fear' from faces is associated with face recognition skill in women.

Two experiments were conducted to explore the relationship between the discrimination of the facial expression of 'fear' in faces and facial recognition. On the basis of the reported role of the amygdala in both processes in patients, we hypothesised that the two skills would be correlated in normal adults. In Experiment 1, a series of tests of facial expression categorisation, of face matching and of familiar and unfamiliar face recognition was conducted on normal young women, for whom psychometric scores were also obtained (n=23). Accuracy of categorisation of fear from faces predicted variance in face recognition accuracy-especially in tasks of unfamiliar face recognition (immediate old-new discrimination). No other correlations between face processing and expression classification were significant. Experiment 2 repeated the expression classification tests and an unfamiliar face recognition test on a new sample of men (n=13) and women (n=16). While there were no sex differences in face recognition, the correlation between 'fear' and face recognition was replicated only for women. These data indicate that the amygdala supports both the specific apprehension of fear in faces and face recognition in adult human females, but that the association may not hold for men. Sex differences in the structure of the amygdala-hippocampal complex suggest a likely cortical substrate for the observed differences. We speculate that social learning, which involves identifying the faces of potentially salient others, and also their attitude to the observer, engages the amygdala more readily in women than in men.