Constraints on learning and their role in language acquisition: Studies of the acquisition of American sign language

Abstract

The general question raised here is why the young child is superior to older children and adults at language acquisition, while at the same time inferior to them in many other cognitive tasks. As an example of the general problem, the paper reviews our own work on the acquisition of complex verbs of American Sign Language (ASL). It begins with an outline of the structure of verbs of motion in ASL, along with possible inductive generalizations a language learner might make concerning this structure. Three lines of research on ASL acquisition are then presented. The first line of research demonstrates that young children, exposed to ASL as a native language, acquire ASL verbs in terms of morphological components, piece by piece, as do children learning spoken language. Moreover, they do so despite alternative generalizations which seem potentially simpler. The second line of research compares native learners of ASL with learners exposed to ASL later in life. This research shows that, while native learners make the morphological componential generalization described, later learners in fact do make alternative generalizations. The third line of research investigates native learners of ASL whose parental input models are late learners. Again it appears that natives perform a morphological analysis, despite the fact that their input is not well organized for such analyses. Taken together, the research shows a striking tendency for children—and only children—to acquire language in a particular fashion. The paper concludes with a discussion of possible explanations for these findings. One possibility is that children have a special set of skills for language acquisition which declines with age. A second possibility is that the cognitive limitations of the child provide the basis on which the child's componential learning occurs, and that the expansion of these cognitive abilities with age is in part responsible for the decline in this type of learning.