ABSTRACT
The possibility that infant vocalizations occur in conjunction with significant changes in experience was tested in a study of seven infants aged 0;8. Each infant was videotaped during an isolated freeplay session with each of three toys. Two indices of changing experience were used to identify portions of the tape where increased vocalizing was expected. The Place Index identified potentially significant changes in experience via major changes in locus of attention. The Reaction Index employed certain rapid changes in expression (e.g., smile, startle, brow change) as indicators of corresponding changes in subjective experience. As predicted, periods of the tape encompassed by either or both of these indices evidenced significantly more vocalizations than remaining portions of the tape. Implications of these results for theories of infant communicative competence and for infant language development are discussed.
