Intonation and Syntactic Structure in the Development of Presupposition.

Although intonations: features in the speech of young children have been considered important, there have been few specific investigations of these features in children's language development. In particular, there have been few attempts to determine the relative importance of intonational vs. syntactic features in children's comprehension of language. The notion of sentence presupposition, which has been the focus of many recent works in linguistics, provides an excellent opportunity to investigate this question since it appears to be the case that certain types of sentence presupposition may be indicated in surface structure either by intonational pattern or by syntactic structure. For example, the two sentences "It is the girl that is petting the dog" and '`The girl is petting the dog" (underlining indicates contrastive stress) are both considered to involve the presupposition that the dog is being petted and to assert that the girl is the one who is doing it. The present research employed a methodology previously developed forthe invesitgation of presupposition in adult language. This consists of presenting a sentence orally-just prior to the tachistoscopic presentation of a picture in which either the presupposed or the asserted, proposition may be misrepresented (e,g., $ 'boy instead of a girl, or a cat instead of a dog in the example above). Thasubject's task is to report whether or not the sentence is a true statement about the picture. Adult subjects show a consistent tendency not to notice discrepancies when they involve syntactically presupposed propositions, whereas they do notice such discrepancies when they involve asserted propositions. Such findings suggest that'the Listener assumes that the presupposed proposition is true and only checks to see if the asserted proposition is misrepresented. A slightly modified version of this task was administered to 30 children at each of three grade levels (grades 2, 5, and 9). In addition to age, two other variables under the were 1) whether the misrepresentation involved the presupposed ort e asserted proposition, and 2) whether the presupposition was indicated in.surface structure by intonation or by syntactic structure. Analysis of variance revealed that all three main effects were signficant at beyond the .005 level; ho,4ever, the finding of most interest to the present research was an interaction between age and manner of marking presupposition. The results suggest that between the age of 8 and 15 years syntactic structure comes to replace intonation as the primary determinant of presupposition. The responses of the youngest subjects (M=8.3 years) were not affected by syntatically marked presupposition, but were highly sensitive to the effect of contrastive stress. The oldest subjects (M=15.1 years), on the other hand, were not significantly' affected by contrastive stressbut responded differentially as a function of syntactic structure. The 5th grae'a subjects (M=11.2 years) appear to be equally sensitive to both intonation and syntactic structure, but neither had as strong an effect as at the other two age levels. These results clearly demonstrate that intonational features are important until relatively late. in the developmental course of language acquisition and suggest a definite shift from sensitivity to intonation and to sensitivity to syntactic structure during a periOd when language development has beer ,,tsuMed to be relatively complete. The effect of the role of the acquisition ke,: Beading skills is considered as a possible means of accounting for these INTONATION AND SYNTACTIC STRUCTURE IP THE DEVELOPMENT OF PRESUPPOSITION The importance of intonational features in the speech of young children has been pointed out by several investigators of child language (Stern and Stern, 1928; Werner and Kaplan, 1963; Lieberman, 1967; Menyuk, 1971); however, very few controlled experiments have actually been conducted in which intonation has been employed as either a dependent or an independent variable. The lack of systematic investigation in this area is testified to by the fact that McNeill's (1970) recent book on the acquisition of language contains no systedatic treatment of the role of intonation in language development.' Studies that have been conducted in this area have usually involved the recording and analysis of children's natural speech patternsin an observational setting. On the basis of such observations it has been noted that during the latter stage of babbling, around 8 to 9 months, children usually go through a period, or stage, in which they produce intonational patterns comparable to adult sentence intonation contours (Nakazima, 1962). This period, which is often noted by parents of young children, has been called the "jargon period" since it sounds like language, but is considered to be meaningless. Engel (1973) has noted, however, that such children appear to employ differential intonation patterns to indicate significant differences in meaning. When children begin producing single word utterances, or holophases, significant differences in intonation pattern are employed (Menyuk and Bernholtz, 1969) and when children begin producing multiple word utterances it is possible to clearly observe intonation patterns which ap.pear to mark utterances as assertions, commands, and questions. While such observational studies can be taken as evidence of the presence of intonational features 1. i1 the speech of young children, it is clear that only controlled experimental procedures can answer the important question of whether such supersegmental features are truly phonemic in children'.s utterances. In this re-. Bard, an earlier study by the present author (llornby and Hass, 1970) clearly revealed that children of 3 to 4 years of age have productive control over the intonational feature of contrastive stress and consistently employ this feature to mark .the new information or focui of a sentence in a controlled setting. Thisfeature can thus be considered to be meaningful or.phonemic for children of this