Melody and Lyrics Are Integrated by Late Infancy During Recognition of Music Learned at Home.

Familiar songs are often more effective than unfamiliar songs at capturing infant attention, regulating emotion, and eliciting rhythmic movements, but how infants rely on lyrics and melody to recognize well-known music from their regular repertoire is not well understood. Here we investigate whether infants use these musical features selectively or interactively during song recognition across early development. Six- (n = 40), 11- (n = 47), and 20-month-old infants (n = 41) participated in an online preferential listening paradigm. We measured infants' attentive listening to a cappella recordings of Wheels on the Bus, an original composition, and two songs mismatched in melody and lyric familiarity (i.e., melody from Wheels paired with lyrics from the novel song, and vice versa). Confirmatory analyses showed that, while 6-month-olds behaved indiscriminately across conditions, the 20-month-olds listened longest to all conditions with at least one unfamiliar component. Exploratory analyses of infant rhythmic movements revealed that the 11-month-olds produced more rhythmic movements to familiar lyrics. Some infants, mostly the older infants, also produced lyrically-relevant gestures more often when those lyrics were present than when they were not (e.g., rolling arms during "wheels" lyrics), across both familiar and unfamiliar songs. Results suggest that by late infancy, infants integrate lyrics and melody when recognizing familiar music.