Infants' Multimodal Requests and Protests Elicit Responses From Mothers During Everyday Home Activities.

During early vocabulary growth, infants use single words to express complete ideas. Requests ("milk") and protests ("no!") are fundamental ways that infants communicate their needs. However, understanding what an infant wants from a single word can be challenging. Caregivers likely rely on infants' gestures and actions to interpret single-word utterances. How common are requests and protests during everyday activities? To what extent do infants accompany their requests and protests with gestures (e.g., points to request) and/or actions (e.g., flailing arms to protest)? Are caregivers more likely to respond to such "multimodal" requests and protests than to infants' words alone (i.e., unimodal speech)? We observed 31 toddlers (12-24 months) with their mothers during everyday interactions at home. In aggregate, infants expressed 2580 single-word utterances, with nearly half being requests (35%) or protests (8%). Most requests and protests (84%) were multimodal, occurring in the context of actions (mostly) or gestures. Unexpectedly, although infants' gestures/actions often "aligned" with their words in meaning or intent (e.g., saying "no" while pushing a toy away), infants also displayed "misaligned" gestures/actions (e.g., saying "no" to one toy while reaching for another). In particular, infants' aligned' multimodal requests and protests were more likely to elicit a response from mothers than were their words alone. Findings underscore the embodied and embedded nature of early communication in the natural home setting: Infants express their intentions by coupling words with gestures/actions, and certain types of multimodal communications are more effective than others in fulfilling their goals.