Abstract:
Recent studies have found that infants show early sensitivity to the characteristic metric structure of the primary language to which they are exposed, and do so long before they acquire the ability to generate speech itself [A. Cutler and J. Mehler, J. Phon. 21, 103--108 (1993); A. Cutler, Cognition 50, 79--81 (1994)]. Vocal exchanges between 30 mothers and their 4-month-old infants were recorded during 10 min of spontaneous face-to-face play. Vocalizations were digitized in 123-ms units, yielding a preliminary result: 27 out of the 30 infants began vocalizing more often at times when maternal speech was already underway (priming) than when the mother was silent. In the present analysis, vocalization distributions are fitted modulo 395 ms---the mean duration of syllabic stress groups in American English. The investigation examines whether infant coactive onsets occur systematically near stress group boundaries or randomly throughout, and, if systematic, whether the infant's tendency to respond metrically varies according to the length of the mother's preceding utterance. Also examined is whether either the mother's speech and/or the infant's onset distribution may be less systematic in the three cases where priming was rare. [Collaboration of Dr. Beatrice Beebe and Dr. Joseph Jaffe is acknowledged.]