Abstract
It is commonly assumed that face identity is determined by visual properties of the face. However, in real life faces are typically learned together with non-facial information that is unique to each identity and can aid identification (e.g., voice, episodic information, semantic information). Here we hypothesized that conceptual similarity between different face images may influence identity decisions beyond their perceptual similarity and objective identity. To test this hypothesis, participants learned pairs of same and different identity faces. All faces were rated for perceptual similarity by an independent group of participants. Conceptual similarity was manipulated by presenting same and different identity faces with the same or different name labels or no labels during learning. During test, participants were presented with the learned face pairs and made similarity decisions as well as identity decisions about each pair of faces. Findings show higher proportion of same identity decisions for faces presented with the same label and lower proportion of same identity decisions for faces presented with different name labels relative to non-labeled faces, indicating a strong effect of conceptual similarity on identity decisions. Performance level that was based only on perceptual similarity was relatively low. However, labels significantly influenced performance level. Labels that were congruent with face identity improved identity decisions, whereas labels that were incongruent with face identity significantly impaired identity decisions. We conclude that perceptual similarity determines identity decisions when no additional information is provided, but may lead to relatively low identification rates. When information about conceptual similarity is provided, it significantly influences identity decisions beyond perceptual similarity and the objective identity of the face. These findings indicate that face identification that is based on perceptual information alone is relatively poor. Conceptual information provides an additional source of information that can improve face identification.