Infants' individuation of human faces across race and identity.

Young infants' face perception capabilities quickly tune to the features of their primary caregiver. The current study examines whether infants distinguish faces in a more conceptual manner using a manual-search, violation of expectation task that has previously been used to test kind-based individuation. We tested how well infants between 11 and 27 months of age individuated faces that varied by superordinate category (human vs. non-human in Experiment 1) subordinate category (individual identity in Experiment 2) or by race (White vs. Black, Experiments 1 & 2). We assessed individuation by quantifying the difference in infants' duration of reaching within an empty box between trials when the box was unexpectedly empty and expectedly empty. We found evidence of individuation across all ages and conditions, but with within-infant variation. On average, infants individuated face from non-face stimuli (Experiment 1), individual face identities (Experiment 2), and White versus Black faces (Experiments 1 & 2). These findings suggest that 1- to 2-year-old infants use distinct human face features to represent individuals across time and space. We discuss this evidence for race-based individuation and related complexities of face identity in terms of implications for conceptual development for faces in the first years of life.