Larry Fenson

Variability in Early Communicative Development.

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.

Short-form versions of the MacArthur Communicative Development Inventories

The MacArthur Communicative Development Inventories (CDIs) are a pair of widely used parent-report instruments for assessing communicative skills in infants and toddlers. This report describes short-form versions of the CDIs and their development, summarizes newly available normative data and psychometric properties of the instruments, and discusses research and clinical applications. The infant short form (Level I, for 8- to 18-month-olds) contains an 89-word checklist for vocabulary comprehension and production. The two parallel versions of the toddler short form (Level II, Forms A and B, for 16- to 30-month-olds) each contain a 100-word vocabulary production checklist and a question about word combinations. The forms may also be useful with developmentally delayed children beyond the specified age ranges. Copies of the short forms and the normative tables appear in the appendices.

Lexical development norms for young children

Developmental norms for young children’s vocabularies have a number of applications in research design, assessment, and intervention, but have previously been very difficult to obtain. In the present study, month-by-month norms for comprehension and production of 396 words from 8 to 16 months, and production of 680 words from 16 to 30 months, were derived from a norming study of 1,789 children between the ages of 8 and 30 months using the MacArthur Communicative Development Inventories (Fenson et al., 1993). The norms are available in the form of a database program, LEX, for MS-DOS-based computers.

A Cross-Linguistic Study of Early Lexical Development.

Abstract Cross-linguistic studies have shown that children can vary markedly in rate, style, and sequence of grammatical development, within and across natural languages. It is less clear whether there are robust cross-linguistic differences in early lexical development, with particular reference to the onset and rate of growth in major lexical categories (e.g., nouns, verbs, adjectives and grammatical function words). In this study, we present parental report data on the first stages of expressive and receptive lexical development for 659 English infants and 195 Italian infants between 8 and 16 months of age. Although there are powerful structural differences between English and Italian that could affect the order in which nouns and verbs are acquired, no differences were observed between these languages in the emergence and growth of lexical categories. In both languages, children begin with words that are difficult to classify in adult part-of-speech categories (i.e., “routines”). This is followed by a period of sustained growth in the proportion of vocabulary contributed by common nouns. Verbs, adjectives, and grammatical function words are extremely rare until children have vocabularies of at least 100 words. The same sequences are observed in production and comprehension, although verbs are reported earlier for receptive vocabulary. Our results are compared with other reports in the literature, with special reference to recent claims regarding the early emergence of verbs in Korean.

Scores on the MacArthur Communicative Development Inventory of children from lowand middle-income families

This study compared the language skills in a group of very low-income toddlers with those of a middle-income sample matched on age and sex. The assessment instrument was the MacArthur Communicative Development Inventory (CDI) for toddlers, a parent report form. The scores for the low-income group were strikingly lower on the three key indices evaluated: size of expressive vocabulary, age of appearance of word combinations, and complexity of utterances. The entire lowincome distribution was shifted about 30% toward the lower end of the middle-income distribution for both productive vocabulary and grammatical development. The magnitude of these income/ social class effects was larger than reported in most prior reports for children in this age range. This finding underscores the cautionary note issued by the CDI developers, which states that the published CDI norms, based on a middle-class sample, may not be directly applicable to low-income samples.

Measuring Variability in Early Child Language: Don't Shoot the Messenger

Feldman et al. criticize the MacArthur Communicative Development Inventories (CDIs) as having too much variability, too little stability, and insufficient ability to predict early language delay. We present data showing that these characteristics of the CDI are authentic reflections of individual differences in early language development rather than measurement deficiencies. We also respond to their critical assertions concerning sociodemographic influences on the CDI scores.

Integrating Language and Gesture in Infancy

Whether language/gesture correlations in early language development can be explained by parallelism or comprehension mediation was examined. Study 1, parental report data for 95 l-year-olds, suggested that word comprehension and production are dissociated in this age range and that the comprehension and production factors map onto distinct aspects of gesture. Study 2 tested 41 13-15month-olds in a task in which the modeled gesture was accompanied by supportive, contradictory, or neutral narratives. Results showed that infants can use adult speech as an aid in reproduction of modeled gestures (comprehension mediation). However, there is still additional variance in gestural production that correlates with expressive vocabulary when comprehension-related variance is removed. Thus, comprehension mediation and parallelism both appear to be operating.

The correspondence between parent report and child performance for receptive and expressive vocabulary beyond infancy

Parent judgement of their toddlers receptive and expressive vocabulary skills was compared with childrens laboratory performance on comprehension and production language tasks. Parents reviewed two separate sets of pictures. For one set they were asked whether their child would recognize the named member of each of 35 pairs of pictured items. For the other set, they were asked whether their child would be able to verbalize each of the pictured objects or actions. After the parent completed each task, the child was tested on the same items. Parents also completed the MacArthur Communicative Development Inventory (CDI), which includes a broader index of expressive vocabulary. The results indicated significant correspondence between parent report and child judgement for comprehension (r = 0.55) and for production (r = 0.67). The CDI expressive vocabulary scale score also correlated with child performance on the expressive vocabulary task (r = 0.78).

Effects of modeling action sequences on the play of twelve-, fifteen-, and nineteen-month-old children.

3 studies examined the relation between the spontaneous occurrence in play of simple 2-part action sequences and the frequency of these sequences and their components following modeling at 12, 15, and 19 months of age. Play following modeling was typically more advanced than play preceding modeling. Moreover, imitation was tied to developmental level. Children at 19 months of age were generally able to imitate complete sequences, though only a few 19-month-olds performed such actions spontaneously. Children at 15 months of age typically did not imitate complete sequences except under simplified experimental conditions, and, even then, their ability to perform sequences was attenuated relative to the 19-month-olds. However, 15-month-olds did imitate many single components of the 2-part combinations and, to a lesser extent, exhibited these components spontaneously. A smaller number of 12-month-olds imitated components, which were rarely displayed spontaneously at this age. The results suggested that a general combinatorial capacity in play emerges between 15 and 19 months of age.

The Effects of Feedback on Perseverative Errors in Preschool Aged Children.

Research using the Dimensional Change Card Sort (DCCS) showed that young children are usually able to sort accurately by an initial rule but are unable to switch to a new rule when the two rules conflict. In 2 experiments, the DCCS was modified to study the effects of feedback on 3- to 5-year-old children in a problem-solving task. In Experiment 1, half of the children in each of two age groups (36 to 44 months and 52 to 60 months) were administered the DCCS task using the standard (no feedback) procedure and the other half received feedback on their post-switch responses. Children who received feedback were able to categorize according to the new (correct) rule, whereas the children in the younger age group who did not receive feedback continued to perseverate. Experiment 2 with 3-year-olds replicated the results from Experiment 1 but found that childrens successful performance with feedback on the card-sorting task did not lead to improved performance on the post-switch phase of a subsequent DCCS task. Successful performance under conditions of feedback in both studies implies that 3-year-olds are capable of shifting their response mode from one rule to an alternate rule under conditions that offer clear guidance. Poor performance on the standard version is interpreted to be a reflection of the inability to monitor their own task performance in the absence of clear contextual cues.