Recognition of individual angry versus happy faces in 6- and 9-month-old infants

With mixed evidence from adults, children, and infants suggesting either anger or happiness superiority in emotion detection, emotion recognition, and recognition of individual faces posing emotional expressions, the current research was undertaken to determine if one or the other emotion would result in higher recognition of individual faces by 6-month-old and 9-month-old infants. The infants were familiarized with an angry or happy face and then given a novelty preference test pairing the familiarized face with a novel face posing the same emotion. Recognition performance of both age groups in each emotion condition was above chance; however, recognition of angry faces was reliably higher than for happy faces. A simple exposure-frequency account of the findings is unlikely because infants experience more happy than angry faces. In addition, lower-level interpretations based on differences in salience, complexity, and discriminability were not supported by image analyses, infant looking times during familiarization, or adult ratings. An account based on the processing of facial expressions as social or communicative signals by infants is discussed, with a possible role for an early negativity bias.