A widely held practice in many studies of child language development and disorders has been to employ an easily calculated numerical metric, mean length of utterance measured in morphemes (MLU), as a ‘general index of grammatical development’. While this practice seems to have found acceptance among many students of child language, the usefulness of MLU past Stage II has been assumed but never empirically tested. This study evaluated the grammatical performance and MLU of 18 normally developing 2- and 3-year-old children and found that MLU did not correlate significantly with age (r = 0·26), nor did it discriminate children's profiles of grammatical development.

The study of language acquisition underwent a major revolution in the late 1950s as a result of the dissemination of technology permitting high-quality tape-recording of children in the family setting. This new technology led to major breakthroughs in the quality of both data and theory. The field is now at the threshold of a possible second major breakthrough stimulated by the dissemination of personal computing. Researchers are now able to transcribe tape-recorded data into computer files. With this new medium it is easy to conduct global searches for word combinations across collections of files. It is also possible to enter new codings of the basic text line. Because of the speed and accuracy with which computer files can be copied, it is now much easier to share data between researchers. To foster this sharing of computerized data, a group of child language researchers has established the Child Language Data Exchange System (CHILDES). This article details the formation of the CHILDES, the governance of the system, the nature of the database, the shape of the coding conventions, and the types of computer programs being developed.

This paper traces the process involved in the bilingual infant's gradual differentiation of his two languages, beginning with the acquisition of a dual lexicon. Word combination is at first based indiscriminately on this dual language source; function words account for a disproportionately large number of tokens used in mixed-language utterances. Universal principles of child syntax are at first applied; later, rules specific to each of the languages are developed separately. The development of self-awareness and sensitivity to standards in the second year provides the essential cognitive underpinning for the child to begin to avoid mixed-language utterances and to choose his language according to his interlocutor. At a still later point the bilingual older child may begin to make use of code-switching strategies appropriate to his or her bilingual community.

This study investigates forms and functions of the perfect in 22 preschool children. Children retold and re-enacted two-sentence stories which modelled the perfect. Although the perfect appeared to be emerging in imitative speech, including certain ungrammatical forms, children varied in the extent to which they used it and appreciated its meaning of current relevance. Three factors were found to influence children's selective imitation and paraphrasing of the perfect: form of the verb (present perfect versus perfect progressive), semantic sense of the perfect, and duration of the lexical verb. Children's performance demonstrates the need to consider not only the developmental frequency of advanced, optional verb forms but the generality of their use and their relation to the child's lexicon.

Some word-finding problems (recorded on tape) of a Dutch two-year-old are reported. The child's attempts at retrieving a certain target form show many characteristics which are typical for ‘tip-of-the-tongue’ experiences. During his lexical search the child produces malapropisms and a blend. The speech errors are analysed, and implications for the character of early lexical organization and the order of lexical form/meaning acquisition are discussed.

This study examined the relationship between mothers' speech and the rate of child syntax growth for 22 2½-year-old children whose speech was sampled at two-month intervals over a six-month period. The relations which appeared suggest that linguistic experience does contribute to syntax development, but that the relation between linguistic input and language growth is different for different domains of language and at different points in the course of development. The results further suggest that there are multiple bases to the benefit of input to language acquisition. One mechanism particularly suggested by the findings is that children analyse the distributional properties of the speech they hear and may induce linguistic structure from the relationship between the structural properties of adjacent utterances in discourse.

Very young children perceive colour normally and possess the concept of colour, but it has been widely reported, on the basis of informal observation or normative assessment, that beginning colour naming is confused and that accurate and consistent colour naming is relatively retarded developmentally. A neutral test was devised to compare experimentally 3-year-olds' abilities to make colour-to-name versus shape-to-name associations. Children learned colour-label associates significantly more slowly than matched shape-label associates, and they committed more errors with colours than with shapes during learning. The design of this study eliminates several explanations often proposed to explicate retarded colour naming, including relative perceptual salience, differential experience, and immature cognitive development, and, in their stead, opens the possibility that the difficulty underlying beginning colour naming may reflect specific word-to-colour associations.

Subjects aged 3;6–9;0 were asked to judge sentences in which much and many modified prototypical and non-prototypical mass and count nouns, and to correct those sentences judged to be deviant. The experimental results indicate that children do not approach the co-occurrence conditions of much and many with various nouns from a semantic point of view, but rather from a morphosyntactic or surface-distributional one. Children learn the proper form that the noun must take in these constructions before they learn the proper choice of quantifier. In addition, they reserve many for use with plural count nouns long before they learn that much is restricted in direct noun modification to use with singular mass nouns.

The interpretation of French statements involving the verbs savoir (‘to know’) and croire (‘to think’) was studied in a group of children aged from 4; 1 to 1. The experiment consisted in asking subjects to attribute four sentences (‘I know that P’, ‘I know that not-P’, ‘I do not know if P’, ‘I think that P’) to fictitious speakers (dolls placed in various situations of knowledge). Results enable us to infer levels of understanding, to locate the main difficulties in the processing of each statement, and to bring out recurrent confusions between the expressions. These results are interpreted as the expression of the processes contributing to the elaboration of ‘modalization’ in the child.

The ‘problem of the error-free progressive’ (Brown 5973) was reexamined. It was hypothesized that young children make errors with the progressive as part of a developmental process. An experiment designed to elicit present-tense verbs is described, using 36 pictures, illustrating 9 process and g stative verbs. Twenty-two children (4; 2 to 6; 6) were tested: all responded mainly in the present tense, and 10 out of 22 produced over-generalizations of the progressive to stative verbs. It is argued that resistance to the progressive is based on a semantic distinction that is modified subsequently in accordance with adult use.

The ability of Icelandic children (aged 4 to 8 years) to identify referents of gender-marked pronouns was tested under three conditions: (i) referents with natural/semantic gender, (ii) familiar referents with grammatical gender, (iii) unfamiliar referents with grammatical gender. Potential formal information about grammatical gender was held constant across all conditions. Children's correct identification of pronoun referents was most highly related to the familiarity of the referents and the availability of natural gender information, not to formal gender information. The results are discussed in light of contradictory findings from German. It is argued that subtle differences in the formal gender systems of.the two languages may underlie the different experimental results and may lead to different developmental patterns.

Experiment I required first, third, and sixth graders to identify the actor or experiencer from active and passive sentences with actional and three subclasses of experiential verbs. Actional passives were understood better than experientials, with no difference among the subcategories of experiential verbs, and no effect of verb frequency or regularity. Response distributions for each verb type did not show two populations of subjects – one knowing and the other not knowing the passive – but approximately unimodal distributions whose mean increased with age. Experiment II studied preschoolers. Again, the actional passives were systematically easier than the experientials, and again, for neither verb type did the response distributions show two distinct subject populations, one competent and the other incompetent. The forms of the distributions cannot be wholly accounted for by fluctuating attention to cues to passivization, but indicate that many children have partial knowledge of the passive (increasing with age). A hypothesis about the nature of this partial knowledge accounts for the gradual acquisition and the difference between the verb types.