A theoretical sequence of cognitive developments is proposed as influencing representational play and language in the second year of life. Scale analysis supported an ordinal sequence of play developments for 102 children (cross-sectional sample, 8 to 24 months of age) and a comparable longitudinal sample of 10 children, despite some inconsistency of temporal placement and overlap of onset time. Structural and temporal links between play and language indicate the influence of developing mental representation, but variation in timing of developments points to the influence of intervening variables. A dynamic systems perspective (E. Thelen, 1989) provides a useful descriptive framework for the transition to language.

Researchers frequently examine the development of the single-word lexicon in the absence of phonetic data. Yet a large body of literature demonstrates relationships between the phonetics of babble and early speech, and it is clear that production skill is essential for establishing a lexicon. This study uses longitudinal productivity criteria to establish children's phonetic skill. Twenty children were followed from age 9 to 16 months, and their level of consistency of vocal patterns was examined in relation to their lexical production, providing a relatively large-sample demonstration of phonetic/lexical relationships at the transition to language. Number of specific consonants produced consistently across the months of observation predicted referential lexical use at 16 months, whereas the transition to reference itself signaled the onset of a sharp increase in numbers of different words produced in a session. The earliest referential speakers exhibited prior consistency in the production of [p/b], which also predominated in their words. Prior use of at least two supraglottal consonants characterized the referential group. Children varied in the specific consonants they produced consistently, and these same consonants, varying according to individual child repertoire, characterized nearly all consonant-based words produced by each child in both of the final 2 months of observation. These findings are interpreted in relation to the children's contemporaneous development of representational ability and pragmatic skill.

Although adult-based words co-occur in the period of transition to speech with a variety of non-word vocalizations, little attention has been given to the formidable problem of identifying these earliest words. This paper specifies explicit, maximally ‘inclusive’ identification procedures, with criteria based on both phonetic and contextual parameters. A formal system for evaluating phonetic match is suggested, as well as a set of child-derived functional categories reflecting use in context. Analysis of word use across two samples of 10 children each, followed from 0;9 to 1;4, provides evidence to suggest that context-bound words can be ‘trained’ by focusing on eliciting language, but that the timing of context-flexible word use remains independent of such training.

Laryngeally produced vocalizations termed grunts function communicatively in many species. The vocalizations and accompanying behavior of 5 human infants videorecorded monthly at the transition to speech were analyzed to determine the frequency, physiological basis, and functional status of grunt production, a phenomenon systematically studied for the first time here. Earliest grunts occurred accompanying movement or effort; next, they accompanied acts of focal attention; and finally they were used in communication. Communicative use was followed by the onset of referential ability in language. This sequence is interpreted in relation to the physiological basis of these vocalizations in respiratory function and to additional developmental variables observed in the children. The findings have implications for the transition to the communicative repertoire in other species in which laryngeal function contributes to communication.

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