Early categorization abilities in young children with Williams syndrome

The present study investigated whether 2- to 6-year-old children with Williams syndrome can form new object categories based on either visual or verbal information alone. Children were presented with six triads of objects. In each triad, two objects either shared visual properties, or were given the same name. Following the presentation of each triad, categorization based on the shared visual or verbal property was evaluated through object manipulation. While the children categorized the objects according to visual cues, they failed to use the verbal cues. These results contrast with previous research showing that typically developing toddlers, who were much younger than the children with Williams syndrome and much less advanced in their vocabulary development, could perform both types of categorization. The present study hence supports the claim that vocabulary acquisition in Williams syndrome develops atypically.