Infants' intermodal perception of canine (Canis familairis) facial expressions and vocalizations.

From birth, human infants are able to perceive a wide range of intersensory relationships. The current experiment examined whether infants between 6 months and 24 months old perceive the intermodal relationship between aggressive and nonaggressive canine vocalizations (i.e., barks) and appropriate canine facial expressions. Infants simultaneously viewed static aggressive and nonaggressive expressions of the same canine and heard an aggressive or nonaggressive bark. Results indicate that 6-month-olds perceived the intermodal relationship for aggressive and nonaggressive barks and the appropriate expression. Results also revealed that in older but not younger infants, the initial or first looks were directed toward the appropriate expression and that older infants also looked proportionately longer to the incongruent expression during the latter half of the test trials. Findings are discussed in terms of perceptual narrowing and the effects of familiarity and experience.