Do 14-17-month-old infants use iconic speech and gesture cues to interpret word meanings?a).

This experimental study investigated whether infants use iconicity in speech and gesture cues to interpret word meanings. Specifically, we tested infants' sensitivity to size sound symbolism and iconic gesture cues and asked whether combining these cues in a multimodal fashion would enhance infants' sensitivity in a superadditive manner. Thirty-six 14-17-month-old infants participated in a preferential looking task in which they heard a spoken nonword (e.g., "zudzud") while observing a small and large object (e.g., a small and large square). All infants were presented with an iconic cue for object size (small or large) (1) in the pitch of the spoken non-word (high vs low), (2) in gesture (small or large), or (3) congruently in pitch and gesture (e.g., a high pitch and small gesture indicating a small square). Infants did not show a preference for congruently sized objects in any iconic cue condition. Bayes factor analyses showed moderate to strong support for the null hypotheses. In conclusion, 14-17-month-old infants did not use iconic pitch cues, iconic gesture cues, or iconic multimodal cues (pitch and gesture) to associate speech sounds with their referents. These findings challenge theories that emphasize the role of iconicity in early language development.