Evidence for a Weak but Reliable Processing Advantage for False Beliefs Over Similar Nonmental States in Adults

The ability to understand the mental states of others has sometimes been attributed to a domain-specific mechanism which privileges the processing of these states over similar but nonmental representations. If correct, then others' beliefs should be processed more efficiently than similar information contained within nonmental states. We tested this by examining whether adults would be faster to process others' false beliefs than equivalent "false" photos. Additionally, we tested whether they would be faster to process others' true beliefs about something than their own (matched) personal knowledge about the same event. Across four experiments, we found a small but reliable effect in favor of the first prediction, but no evidence for the second. Results are consistent with accounts positing specialized processes for (false) mental states. The size of the effect does, however, suggest that alternative explanations such as practice effects cannot be ruled out.