The Effects of Children's Language Comprehension ...

THE EFFECTS OF CHILDREN'S LANGUAGE COMPREHENSION LEVEL ON ADULTS' CHILD-DIRECTED TALK A N N E VAN KLEECK

University of Texas, Austin

ROBERT L. CARPENTER University of Washington, Seattle

The present study attempted to test quasi-experimentally the hypothesis that children's language comprehension level is the major determinant of the modifications characteristic of child-directed talk (CDT). Language comprehension level was varied by selecting four-year-old, language-impaired children with two levels of comprehension. Data on 21 measures of structural and pragmatic aspects of CDT were obtained from videotapes of 20 half-hour, freeplay sessions in which each of ten adults talked individually with one child from each level. A t test for paired samples generated four significant differences (p < 0.05). Language addressed to the high comprehending children contained (1) more frequent use of the semantic category state, (2) greater lexical diversity, (3) more frequent reference to nonpresent objects, persons, and events, and (4) less frequent nonverbal cueing. Variation in the children's comprehension strategies appears to provide a better explanation for these differences than variation in their comprehension of language structure. An alternate explanation of the results, the conversational model, proved of limited value in explaining structural CDT modifications. W h e n adults talk to y o u n g c h i l d r e n , t h e i r u t t e r a n c e s are g e n e r a l l y shorter, slower, h i g h e r - p i t c h e d , m o r e controlling, and m o r e c o n c r e t e than w h e n t h e y talk to o t h e r adults (for a r e v i e w o f studies see Slobin, 1975). As y o u n g c h i l d r e n d e v e l o p , talk a d d r e s s e d to t h e m b e c o m e s i n c r e a s i n g l y m o r e like talk a d d r e s s e d to adults; u t t e r a n c e s b e c o m e longer, less r e d u n dant, m o r e d i v o r c e d from the h e r e - a n d - n o w , etc. It w o u l d b e useful to k n o w if this c h a n g e in adult talk is a n e c e s s a r y or e v e n a facilitating condition for a child's acquisition o f language. In o r d e r to address this q u e s t i o n , h o w e v e r , it is first n e c e s s a r y to e x a m i n e w h a t causes adults to c h a n g e the w a y t h e y talk to c h i l d r e n . Systematic c h a n g e s in c h i l d - d i r e c t e d talk ( C D T ) are i n f l u e n c e d b y such variables as cultural i n f l u e n c e (Blount, 1972; Farwell, 1973; F e r g u s o n , 1964) and c o m m u n i c a t i v e situation (Broen, 1972; B u i u m , R y n d e r s , and T u r n u r e , 1974; Siegel, 1963; S i e g e l and H a r k i n s , 1963; Snow, 1972). H o w e v e r , m a n y changes a p p e a r to b e adjusted to d e v e l o p i n g aspects of y o u n g c h i l d r e n t h e m s e l v e s . T h e s e changes o c c u r in b o t h structural a n d pragmatic features o f C D T . Structurally, m e a n l e n g t h o f u t t e r a n c e (MLU), 546

Downloaded From: http://jslhr.pubs.asha.org/ by a ReadCube User on 06/07/2016 Terms of Use: http://pubs.asha.org/ss/rights_and_permissions.aspx

a measure considered to reflect the general semantic-syntactic complexity of CDT, was significantly longer to older children in eight of nine studies (Cross, 1975; Fraser and Roberts, 1975; Glanzer and Dodd, 1975; Longhurst and Stepanich, 1975; Moerk, 1975; Newport, 1976; Phillips, 1971, 1973; Shatz and Gelman, 1973; Snow, 1972). Pragmatically, linguistic redundancy (repetitions, imitations, etc.) decreases in CDT to older children (Cross, 1975; Newport, 1976; Schacter, Fosha, Stemp, Brotman, & Ganger, 1976). At least part of the change in CDT described above appears to be in response to change in the feedback from the child being addressed (Snow, 1972). Age, however, covaries with numerous aspects of development. Children simultaneously develop physically, socially, mentally, and linguistically. Changes in a child's physical size, social skills (including the child's knowledge of language as a social act or pragmatics), nonverbal cognitive skills, and production or comprehension (or both) of language structure are potential influences interacting with age. What then are the specific aspects of the child's development that shape CDT modifications? The two most frequently discussed hypothetical models suggest different specific child variables. These different variables necessitate differing views of the role of the linguistic environment in the language acquisition process. The first model we shall call the comprehension model; the second, the conversational model. COMPREHENSION MODEL MODIFICATIONS

OF CDT

According to the comprehension view, child-directed talk (CDT) is adjusted to the language comprehension level of the child. The adult's goal is to produce language the child can understand. Hence, adults use the child's apparent comprehension of language as feedback in shaping their CDT (Bohannon and Marquis, 1977; Cross, 1977; Ervin-Tripp, 1971; Glanzer and Dodd, 1975; Lord, 1975; Wedell-Monnig and Westerman, 1977). This means that children exercise control over their own linguistic environment. For example, by giving more comprehension cues to structurally simpler utterances, the child shapes the structural complexity of the linguistic input he receives. By giving more comprehension cues to CDT with greater redundancy, the child shapes the redundancy aspect of CDT pragmatics. Other structural and pragmatic aspects of the linguistic environment are shaped in a similar fashion. The comprehension model supports a relatively strong role for the linguistic environment in the child's acquisition of language structure. Because the structural complexity of CDT is tuned to the child's apparent comprehension of language structure, the discrepancy between what the child knows and what he hears is minimized. To the extent that CDT is organized by the adult to match the child's existing knowledge of fanVAN KLEECK, CARPENTER:Adults" Child-Directed Talk 547


guage structure, the child's task of organizing the linguistic data (CDT) he receives is lightened. If the input (CDT) is tuned to the child's knowledge of language structure, the child is helped in analyzing incoming linguistic data, in determining generalities, and in further building his knowledge of language structure. CONVERSATIONAL MODEL MODIFICATIONS

OF CDT

Further research has evolved an alternate explanation of child-directed talk (CDT) modifications often referred to as a conversational model (Newport, 1976; Newport, Gleitman and Gleitman, 1977; Shatz & Gelman, 1977; Snow, 1977). These investigators deny that the structural complexity of C D T is adjusted to the child's d e v e l o p i n g k n o w l e d g e of language (either comprehension or production). They argue that it is feedback concerning the child's "nonsyntaetic cognitive deficits" (Newport, 1976) which influences the structural complexity of CDT. Consider the following conversational model. Adults are interested in maintaining social contact wRh children. To do so, the adult must get and keep the child's interest by selecting topics attractive to the child. What children notice and do is based upon their nonverbal cognitive understanding of the world. Hence, when an adult uses a child's activities and focus of attention as feedback, the adult adjusts topics in CDT to the child's implicit understanding. These topics determine the semantic content and thus indirectly the syntactic complexity of CDT. The simpler syntax of CDT is thus a by-product of the restrictions on message content. The conversational model does not support the hypothesis that CDT plays a strong role in facilitating the child's acquisition of language structure. If CDT is not tuned to a child's knowledge of language structure, the discrepancy between what the child knows and what he hears may be very large. This model, then, indirectly supports a version of the nativist view that a child brings innate language-specific structures to the task of learning language. These compensate for large discrepancies between the child's knowledge of language structure and the structure of the language he hears. METHODOLOGICAL

PROBLEMS STUDIES

WITH

PREVIOUS

Several studies have attempted, with contradictory results, to demonstrate the influence of children's language comprehension level on CDT (Cross, 1977; Snow, 1977; Experiment 1 of Bohannon and Marquis, 1977). Because these studies were observational or correlational or both, they do not establish that any child behavior causes CDT modifications. Two 548 Journal of Speech and Hearing Research

23 546-569 September 1980


other experimental studies concluded that the comprehension model had been supported (Bohannon and Marquis, 1977; Wedell-Monnig and Westerman, 1977). Wedell-Monnig and Westerman compared talk addressed to normal-hearing versus hearing-impaired children matched for age and sex. However, their data may have been contaminated by child variables other than language comprehension level because there are other ways besides language comprehension ability in which hearing-impaired children differ from their normal-hearing peers. In Bohannon and Marquis (Experiment 2, 1977) the influence of a child's comprehension feedback was determined for only a very restricted set of CDT utterances and, as such, cannot be generalized to account for the complexity of an entire CDT corpus. PURPOSE

OF THE

STUDY

Although current theory in child language development seems to favor the comprehension model, convincing evidence demonstrating that adults modify their talk to children as a function of a child's comprehension level is not available. The current study was an attempt to overcome the design problems found in previous studies exploring the validity of the comprehension model as an explanation for C D T modifications. More specifically, the study explored the influence of the varying language comprehension levels of language-disordered children on the language addressed to them by previously unacquainted adult women. METHOD In reviewing methods of assessing the effects of children's behavior on adults, Bell (1971, 1974) suggested bringing children with varying levels of behaviors along a defined dimension into interaction with adult subjects with whom they have had no previous experience. Bell's suggestion was followed in this study. Adult subjects interacted individually with two children who had different levels of language comprehension. In order to hold all relevant variables constant, except language comprehension, children with language impairments were used to create the experimental conditions described below. In order to use the approach suggested by Bell, a preliminary investigation was conducted to determine how well adults must know children before they make child-directed talk (CDT) modifications. Furthermore, since some of the 47 measures used in the pilot study (Appendix A) were not used in other CDT research, it was necessary to determine which of these measures would be sensitive to changes in CDT. The preliminary study analyzed the CDT of 16 women in a half-hour free-play interaction with one normally developing 3V2 year old and one developmentally deVAN KLEECK, CARPENTER:Adults' Child-Directed Talk


549

l a y e d 31/2 y e a r old. T h e adults w e r e p r e v i o u s l y u n f a m i l i a r w i t h the children. T h e r e w e r e two c h i l d r e n r e p r e s e n t i n g each o f t h e s e two c o n d i t i o n s , b u t each a d u l t i n t e r a c t e d w i t h just one n o r m a l l y d e v e l o p i n g and one d e v e l o p m e n t a l l y d e l a y e d child. T h e two n o r m a l l y d e v e l o p i n g c h i l d r e n w e r e j u d g e d as p e r f o r m i n g w i t h i n n o r m a l limits (within one s t a n d a r d d e v i a t i o n o f the m e a n for t h e i r c h r o n o l o g i c a l age) o n several s t a n d a r d i z e d tests covering n o n v e r b a l cognitive skills (Leiter International Performance Scale, A r t h u r Adaptation, Arthur, 1952) and e x p r e s s i v e (Developmental Sentence Analysis, L e e , 1974) a n d r e c e p t i v e (Peabody Picture Vocabulary Test, D u n n , 1959; and the Test for Auditory Comprehension of Language, Carrow, 1973) l a n g u a g e d e v e l o p m e n t . T h e o t h e r two c h i l d r e n w e r e j u d g e d as b e i n g d e v e l o p m e n t a l l y d e l a y e d b y a diagnostic t e a m consisting o f a nurse, o c c u p a t i o n a l therapist, pediatrician, psychologist, s p e e c h a n d l a n g u a g e pathologist, a n d an audiologist. Both c h i l d r e n w e r e f u n c t i o n i n g b e t w e e n a p p r o x i m a t e l y 1V2 and 2Vz years in gross and fine motor, social and selfhelp, c o g n i t i v e a n d l a n g u a g e skills. E x p r e s s i v e l a n g u a g e was at a singlew o r d l e v e l for b o t h c h i l d r e n . Both c h i l d r e n had n o r m a l physical g r o w t h (height a n d w e i g h t w i t h i n normal limits for c h r o n o l o g i c a l age) a n d ap-

TABLE 1.Means and standard deviations (in parentheses) for measures of language structure which revealed significant differences at p < 0.05 in the preliminary experiment (n = 16; two-tailed probability) and means and standard deviations on these same measures in the main experiment (n = 10; one-tailed probability). The first two measures represent mean values per utterance and the rest represent frequency of occurrence per 100 utterances.

Measures 1. Mean length of utterance (MLU) 2. Mean number of semantic categories/utterance 3. No verb 8. Denial 9. Attribution 10. Possession 13. State 16. Time 17. Coordinate 18. Causality 21. Epistemic 24. Extent 27. Lexical diversity (LTTR) *Results significant at p

Main Experiment High Low CompreComprehension hension Listener Listener Condition Condition

Preliminary Experiment Developmentally Normal Delayed Listener Listener Condition Condition