Hypersociability in Williams syndrome: a role for the amygdala?

We read with great interest the paper of Riby et al. regarding atypical, unfamiliar face processing in Williams syndrome (WS; Riby, Doherty-Sneddon, & Bruce, 2008a). It offers considerable insight into the mechanism of facial perception in humans and a further elaboration of the hypersociability observed in patients with Williams syndrome. We would like to suggest that the neurologic mechanisms underlying the hypersociability in WS may be attributable to an impaired recognition of facial expressions of threat, a feature that localises to the amygdala.