No abstract

Data from parent reports on 1,803 children--derived from a normative study of the MacArthur Communicative Development Inventories (CDIs)--are used to describe the typical course and the extent of variability in major features of communicative development between 8 and 30 months of age. The two instruments, one designed for 8-16-month-old infants, the other for 16-30-month-old toddlers, are both reliable and valid, confirming the value of parent reports that are based on contemporary behavior and a recognition format. Growth trends are described for children scoring at the 10th-, 25th-, 50th-, 75th-, and 90th-percentile levels on receptive and expressive vocabulary, actions and gestures, and a number of aspects of morphology and syntax. Extensive variability exists in the rate of lexical, gestural, and grammatical development. The wide variability across children in the time of onset and course of acquisition of these skills challenges the meaningfulness of the concept of the modal child. At the same time, moderate to high intercorrelations are found among the different skills both concurrently and predictively (across a 6-month period). Sex differences consistently favor females; however, these are very small, typically accounting for 1%-2% of the variance. The effects of SES and birth order are even smaller within this age range. The inventories offer objective criteria for defining typicality and exceptionality, and their cost effectiveness facilitates the aggregation of large data sets needed to address many issues of contemporary theoretical interest. The present data also offer unusually detailed information on the course of development of individual lexical, gestural, and grammatical items and features. Adaptations of the CDIs to other languages have opened new possibilities for cross-linguistic explorations of sequence, rate, and variability of communicative development.

Results are reported for stylistic and developmental aspects of vocabulary composition for 1,803 children and families who participated in the tri-city norming of a new parental report instrument, the Mac Arthur Communicative Development Inventories. We replicate previous studies with small samples showing extensive variation in use of common nouns between age o;8 and 1 ;4 (i.e. 'referential style'), and in the proportion of vocabulary made up of closed-class words between 154 and 2;6 (i.e. 'analytic' vs. 'holistic' style). However, both style dimensions are confounded with developmental changes in the composition of the [*]

The relationship between language and symbolic gesture was studied in a group of young children who were in the lowest 10% for language production for their age based on information obtained from language inventories filled out by their parents. On a single scheme imitation task, designed to be a gestural analog of lexical production, subjects performed like controls matched for language production. On a multischeme imitation task, designed to be a gestural analog of syntax, subjects performed like age-matched controls, and significantly better than langnage-matched controls. Potential reasons for this dissociation are discussed in the context of predictors of early language success or impairment.

This paper describes the early lexical development of a group of 328 normal Spanish-speaking children aged o;8 to 257. First the development and structure of a new parent report instrument, Inventario del Desarollo de Habilidades Communcativas is described. Then five studies carried out with the instrument are presented. In the first study vocabulary development of Spanish-speaking infants and toddlers is 523 19-2 CHILD LANGUAGE compared to that of English-speaking infants and toddlers. The English data were gathered using a comparable parental report, the MacArthur Communicative Development Inventories. In the second study the general characteristics of Spanish language acquisition, and the effects of various demographic factors on that process, are examined. Study 3 examines the differential effects of three methods of collecting the data (mail-in, personal interview, and clinic waiting room administration). Studies 4 and 5 document the reliability and validity of the instrument. Results show that the trajectories of development are very similar for Spanishand English-speaking children in this age range, that children from varying social groups develop similarly, and that mail-in and personal interview administration techniques produce comparable results. Inventories administered in a medical clinic waiting room, on the other hand, produced lower estimates of toddler vocabulary than the other two models.