Nonverbal emotion perception and vocabulary in late infancy.

Language has been proposed as a potential mechanism for young children's developing understanding of emotion. However, much remains unknown about this relation at an individual difference level. The present study investigated 15- to 18-month-old infants' perception of emotions across multiple pairs of faces. Parents reported their child's productive vocabulary, and infants participated in a non-linguistic emotion perception task via an eye tracker. Infant vocabulary did not predict nonverbal emotion perception when accounting for infant age, gender, and general object perception ability (β = -0.15, p = .300). However, we observed a gender difference: Only girls' vocabulary scores related to nonverbal emotion perception when controlling for age and general object perception ability (β = 0.42, p = .024). Further, boys showed a stronger preference for the novel emotion face vs. girls (t(48) = 2.35, p = .023, d= 0.67). These data suggest that pathways of processing emotional information (e.g., using language vs visual information) may differ for girls and boys in late infancy.