This paper reports on the acquisition of the voicing contrast in Mexican–Spanish word-initial stops. In Study 1, three monolingual children were recorded every two weeks for seven months, beginning when the children were about 1; 7. In Study 2, four monolingual children about 3; 10 were recorded once or twice. Two analyses were done. Instrumental analysis of the stop productions revealed that not even by age 3; 10 were the children consistently distinguishing between voiced–voiceless stop cognate pairs on the basis of adult-like voice-onset time characteristics. The spirantization analysis, however, more clearly revealed the children's phonological knowledge. Discussion focuses on the implications of the data for phonological development in general and for the phonological description of voicing in Spanish.

The present study explored children's perceptual capabilities with regard to the temporal acoustic cue of differential vowel duration, comparing children's perceptual identifications to those of adults. Three-year-old children, six-year-old children, and adults participated in two experiments, in which they were asked to identify (as voiced or voiceless) CVC words with uniformly voiceless final obstruents, but in which vowel duration was systematically varied. Children were also asked to identify a set of CONTROL stimuli, in which both closure voicing and vowel duration differences were present. Results indicate that both subject age and vowel duration of the TEST stimuli significantly affect identification responses. Adults and six-year olds evidence perceptual cross-over in their judgements for the TEST stimuli, while three-year-olds do not seem to change their identifications, regardless of variations in vowel duration. However, for both groups of children, the accuracy of identifications was greater for originally voiced stimuli on the CONTROL set of words, in which more than one potential cue to the voicing distinction was present. These results suggest that there is a complex and somewhat paradoxical relationship between developing production and perception which deserves further research. Children may consistently produce a phonetic difference (vowel duration) which they are unable to use as the SOLE perceptual cue for a phonological contrast.

This study demonstrates a striking absence of variability in the speech which mothers address to children of the same age within the 1- to 5-year range. Speech to children of 1; 0, 1; 8, 2; 3 and 5; 0 years was analysed for aspects of syntactic, semantic, pragmatic and discourse structure. Discriminant function analyses showed that the age of the child to whom a mother was speaking could be predicted very accurately from her speech. The rate at which mothers' speech changed was greatest when the children were 1; 8–2; 3, and least when they were 2; 3–5; 0. These trends in the evolution of the maternal speech register are interpreted as responses to concurrent changes in children's language behaviour.

The speech of 36 mothers to their infants in a face-to-face situation at ages 6, 13 and 26 weeks was compared with unfamiliar adults' speech to the same infants, the mothers' speech to an interviewer, and their conversations with the same children 2 years later. Speech to the infants was quite different from so-called ‘baby talk’, but contrary to other authors the speech to infants was even shorter, more repetitive, and more limited in content than the speech to language-learning children. Differences appear due to the infant's changing status in the relationship, from a potential to an actual conversant.

Pronoun mastery demands a knowledge of speech roles and an ability to identify oneself and others in those roles. Twenty-one girls' (age 1; 6–2; 6) knowledge of my, your, and her was assessed when they were speakers, addressees and non-addressed listeners. My and your were at first understood correctly only when referring to the child's own speech role: your was comprehended when the child was addressed, though not produced correctly by the child; my was used by the child as speaker, while still not comprehended correctly when used by others. The first consistent production of her referred to dolls. Children thus were initially aware of speech roles, but only when they themselves occupied those roles.

Two experiments were devised in order to better understand the relationship between temporal before and after and their spatial counterparts. In Experiment I, sixty adults were probed for their spatial metaphoric understanding of temporal before and after. Although H. Clark proposed that temporal before and after were derived from their spatial counterparts, Experiment I did not support that notion. In fact, the subjects overwhelmingly reported that temporal before was more related to spatial after and that temporal after was more related to spatial before. Since it has been shown by numerous investigators that temporal before is acquired before temporal after by children, the evidence from Experiment I suggested that their spatial relatives may be acquired similarly. Experiment II presents evidence that indeed spatial after is understood better by three-year-old children than spatial before. This evidence is coincident with the adult reports in Experiment I.

The acquisition of the morphological rules for plural, agentive, and diminutive suffixes in Dutch was studied. Subjects included 7- and 12-year-old native speakers, and second-language learners in three age groups (5–10 years, 12–18 years, and adult). The first- and second-language learners showed very similar orders of acquisition for the rule systems governing plural and diminutive, but the second-language learners showed a subtle form of interference from their first language in acquiring the agentive. The findings suggest that morphological acquisition proceeds piecemeal, with the learning of specific word ending + allomorph sequences, and that generalizations at the level of morphological rules may not be made even after several years of correct performance with the allomorph in question.

The present study asked three questions. To what extent does the pre-school child use pronouns ambiguously in a naturalistic situation? Under what circumstances is such referential ambiguity likely to arise? How does the pre-school listener respond to such ambiguity? Sixteen pre-schoolers, four pairs of boys and four pairs of girls, were videotaped in a play situation. The results indicate that ambiguity of reference frequently arises, especially when disambiguation can be achieved only by verbal rather than non-verbal information. The presence of such ambiguity did not, however, influence the social responsiveness of the listener.

Ostensive definitions of words are ambiguous as to their referent. In a study of 40 mother–infant dyads engaged in looking at picture-books, it was found that 95% of ostensive definitions referred to the whole object depicted, rather than to its parts, attributes or actions. On the rare occasions when mothers named parts of objects, they avoided misunderstanding of the level of reference either by naming the part immediately after naming the whole, or by including a reference to the whole in the definition of the part. What's that? questions are not used to request labelling of the part.