Testing additivity of kinship information in complementary facial regions

Allocentric kin recognition - recognition that individuals are close genetic relatives - plays an important role in social organization and kin selection (Hamilton, 1964). Facial judgments - including kin recognition - are typically modeled as a form of cue combination but with the identity of cues currently unknown. In two experiments, we examined human ability to classify pairs of children as siblings or not siblings and tested whether kinship information in different facial regions combined as statistically independent cues. We used complementary masks to occlude a face region or present it in isolation (Exp. 1 eye region; Exp. 2: mouth region) and tested whether we could predict performance with the unmasked face from performance in the two masked conditions.