Does categorical perception in the left hemisphere depend on language?

Categorical perception (CP) refers to the influence of category knowledge on perception and is revealed by a superior ability to discriminate items across categories relative to items within a category. In recent years, the finding that CP is lateralized to the left hemisphere in adults has been interpreted as evidence for a kind of CP driven by language. The present research challenges this conclusion. In 2 experiments, we found that CP for novel object categories was stronger in the left hemisphere than in the right, consistent with a role for language. However, both labeled and unlabeled categories gave rise to such effects, and to comparable degrees. These results suggest that left-lateralized CP does not depend on language but rather may reflect the left hemisphere's more general propensity for categorical processing. Our findings raise implications for research on linguistic relativity.