Toddlers with Williams syndrome process upright but not inverted faces holistically.

Holistic processing of upright, but not inverted, faces is a marker of perceptual expertise for faces. This pattern is shown by typically developing individuals beginning at age 7 months. Williams syndrome (WS) is a rare neurogenetic developmental disorder characterized by extreme interest in faces from a very young age. Research on the effects of inversion on holistic processing of faces by older children and adults with WS has produced mixed results. Younger children with WS were not included in these previous studies. Using the habituation switch paradigm, we demonstrated that 15-35-month-olds with WS process upright, but not inverted, faces holistically. This study provides evidence of perceptual expertise for faces in individuals with WS early in life.