TEMPORAL RELATIONSHIPS BETWEEN GAZE AND VOCAL BEHAVIOR IN PRELINGUISTIC AND LINGUISTIC COMMUNICATION

This work reports longitudinal evaluation of the temporal relationship s between gaze and vocal behavior addressed to interactive partners (m other or experimenter) in a free-play situation. Thirteen children wer e observed at the ages of 1;0 and 1;8 during laboratory sessions, and video recordings of free-play interactions with mother and a female ex perimenter were coded separately for children's vocal behavior (vocali zations and words) and gaze toward their interactive partners. The dif ference between the observed and expected cooccurrence of these two co mmunicative behaviors was evaluated by transformation into z-scores. T he most important findings are related to differences in the temporal relationship observed at age 1;0 between gaze and vocalizations and at age 1;8 between gaze and words. At the earlier age, the infants who e xhibited greater coordination between gaze and vocal behavior than was expected by chance (z-score > +1.96) preferred to look at the interlo cutor at the beginning of the vocal turn. Instead, when they were olde r and began to produce words, they frequently looked at the interlocut or at the end of the vocal turn. These results are interpreted as refe rring to characteristics of conversational competence in the prelingui stic and linguistic periods. Moreover, looking at the interlocutor at the beginning of the vocal turn at age 1;0 was found to be related to language production at age 1;8, highlighting a significant relationshi p between conversational competence during the prelinguistic period an d language acquisition.