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, browchange 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.

This work describes the importance of the transcription process in studies of speech and language acquisition. Using data collected from a hearing child of deaf parents, the three authors derived independent transcriptions of the same speech sample and systematically compared their transcripts with each other and with the best estimate of the speaker's actual productions. The resultant transcripts were used to produce two descriptions of this child's phonological system, one based on a liberal estimate and one on a conservative estimate of the potential error in the transcripts. Discussion includes suggestions for deriving percentages of inter-transcriber agreement and the utility of such figures as a metric of transcription difficulty as well as transcriber ability.

Most processes in child phonology have as their domain a single word or a smaller chunk of phonological material. Processes that involve the interaction of two or more words have never been examined. In a diary study of the speech of one child acquiring English, there were eight between-word processes. All were optional and occurred in fairly restricted environments. Most of the processes were of short duration. Consequences for the study of child phonology are discussed.

Two studies of children's early language comprehension were performed using the signal detection paradigm introduced by Thomas et al. (1981). Experiment 1 replicated the original findings of Thomas et al., demonstrating that 13-month-olds understand a word that a parent reported they would understand and did not understand a word that a parent reported they would not. In Experiment 2, the procedure was modified to test for overextensions in early language comprehension. On half of the trials, children saw an array of objects including a referent for a ‘known word’. On the other half, the array included an object perceptually similar to the referent of the known word, but which itself was not an appropriate referent (e.g. an apple instead of an orange). Though the children demonstrated an understanding of the known word, they also overextended that word to the inappropriate referent. Mechanisms for such overextensions are discussed, as is the general relationship between comprehension and production.

Four mother–child dyads were videotaped in a longitudinal study of the relationship between linguistic input to children and early lexical development. Diary records were also kept by the mothers and, together with the videorecordings, were used to identify the contexts in which the children produced their first words. These were compared with the contexts in which the mothers used these same words. It was found that there was a strong relationship between the children's initial use of words and the most frequently occurring use of these words by the mothers. It was also found that although the majority of the children's first words were context-bound, a significant number were referential. The implications of these findings for current theoretical proposals concerning early lexical development are discussed.

A modelling experiment was conducted to determine if children would benefit from observing speech not addressed to them in discovering the correct use of first and second pronouns. Imitative behaviours of 18 English-speaking children who were about to learn personal pronouns were analysed under two modelling conditions. The non-addressee condition provided the child with systematic opportunities to observe the parents saying me/you with pointing actions directed towards each other as well as the parents saying me/you with pointing action directed towards the child. The addressee condition provided the child only with systematic opportunities to observe the parents saying me/you with pointing actions directed towards the child. Only children in the non-addressee condition imitated their parents' pointing actions and use of me/you without errors, suggesting that even children under two years old can attend to and can learn from speech not addressed to them.

The count/mass distinction represents a categorical differentiation of nouns into count nouns which can be individuated when quantified (e.g. a car, several tables) and mass nouns which may not (cf. *a water, *several sands). The emergence of this distinction was examined in the longitudinal speech data of two children. In the first analysis, use of count nouns and mass nouns was compared in noun phrase contexts that require count nouns (e.g. a X, another X). It was found that from the earliest samples children used more count nouns in these contexts, hence showing a distributional distinction of noun types. This result suggests very rapid acquisition of count/mass subcategories. A series of further analyses assessed the possibility that early differentiation of count and mass nouns may be due to rote learning. No evidence was found for this proposal. A final analysis examined the development of a rule that requires that singular count nouns must be modified by a determiner. Acquisition here was found to be more protracted in nature since determiners are not used consistently in ‘telegraphic’ speech. Problems concerning the learnability of the obligatory determiner rule are discussed along with some speculations concerning the role of semantics in the acquisition of the count/mass distinction.

This study investigated the degree to which cue validity, as estimated from textual analyses, predicts the actual strength of grammatical cues as they are used by speakers of Hebrew. An experiment was conducted to determine the differential strengths of the linguistic cues employed by Hebrew speakers when assigning the role of patient in sentences. Monolingual Hebrew-speaking subjects 4, 5, 7, and 9 years old, as well as adults, were tested using a sentence-picture verification task. Six cues were included in the study: word order, the accusative object marker, the reflexive noun phrase and three verbal derivations. By presenting subjects with sentences which set these cues in competition with one another, a measure of the strength of each cue was obtained. The results of a regression analysis revealed strong positive correlations between estimated cue validities and actual cue strengths for all but the youngest age groups. These results were interpreted as suggesting that cue validity is highly predictive of actual cue strengths. In addition, the strengths of the six cues varied as a function of the subject's age. Two additional factors were hypothesized to account for the performance of the older subjects: increased sensitivity to the reliability of cues and discourse-based constraints.

This study determined what types of speech act 5– to 13-year-olds, and adults, would call Promising by asking questions following stories in which a speaker sometimes violated Searle's (1969) rules, by promising an event outside the speaker's control (PREDICTING) or by promising that a past action had been performed (ASSERTING). By 9 years of age children could distinguish between promising and predicting in terms of the speaker's responsibility for the outcome. 11- and 13-year-olds correctly said the speaker did not promise in cases of predicting, but only a few of them were correct for asserting. Even older children said the speaker did not promise when the promise was unfulfilled. Children do not think of promising as simply a speech act. The adult conception is closer to, but not the same, as Searle's.