The “Sh-Ape Bias” in Non-Linguistic Categorization: Comparisons between Children and Other Apes

Abstract

ABSTRACTChildren show a bias toward information about shape when labeling or determining category membership for novel objects. The body of work with human children suggests that the shape bias is not restricted to linguistic contexts but is highly contingent on task demands. Testing nonhumans could provide additional information about the salience of shape cues in the absence of linguistic relevance. In order to assess the salience of shape versus color using an identical task in children and apes, we presented two adult zoo-housed chimpanzees (Pan troglodytes) and 56 three–five-year-old children with a relational matching task in which samples and comparison stimuli matched on either shape or color. Whereas children of all ages performed above chance on the task, chimpanzees performed at close to chance levels overall. However, closer inspection revealed that, whereas children performed better on shape (86%) versus color trials (78.5%), chimpanzees showed the opposite pattern, performing at chance on shape trials (49%) and above chance on color trials (72%). Children also made quicker responses on shape versus color trials, whereas chimpanzees showed the opposite pattern. Whereas shape is a highly salient cue for Western children, color may be a more salient natural cue in nonhuman primates’ natural environments. Thus, the shape bias does not appear to be an evolutionarily ancient bias when assigning category membership.