Effects of object familiarity on children's silent gestures.

When gesturing (with or without speech) actions done with objects, young children and adults with apraxia often produce a body-part-as-object (BPO), like an extended finger for a toothbrush. In contrast, older children and neurotypical adults often produce an imagined object (IO), like pretending to hold a toothbrush. The purpose of this study was to test whether IOs are produced when children have a rich conceptual understanding of the functions of an object. If so, children should produce more IOs (relative to BPOs) with familiar than with unfamiliar objects. Children between three and five years old were asked to demonstrate what to do with either familiar or unfamiliar objects. As predicted, the children produced more IOs with familiar than unfamiliar objects. These results are consistent with the argument that children's handshape when gesturing reflects the richness of their understanding. Developmental change likely occurs as children develop a rich understanding of many objects.