Janet Fodor and William Sakas
The study of natural language learnability is necessarily multidisciplinary. Its aim is to devise and evaluate possible psychological mechanisms by which a system bounded by the cognitive capabilities and linguistic exposure of a young child might be able to arrive at rich knowledge of an adult human language. The abstract formal models that launched this discipline have over the years become increasingly responsive to theoretical linguistic discoveries about the properties of natural language grammars, many embracing parameter theory in particular as a systemization of the ways in which grammars may differ. The concept of grammar acquisition as the setting of parameters has inspired a number of recent learning models, whose details are compared and contrasted here. But it has not swept away all learnability problems, as it has become clear that the input cues needed to trigger the correct parameter settings are often ambiguous or opaque.
Richard P. Meier
This essay considers the acquisition of sign languages as first languages. Most deaf children are born to hearing parents, but a minority have deaf parents. Deaf children of deaf parents receive early access to a conventional sign language. The time course of acquisition in these children is compared to the developmental milestones in children learning spoken languages. The two language modalities—the oral-aural modality of speech and the visual-gestural modality of sign—place differing constraints on languages and offer differing resources to languages. Possible modality effects on first-language acquisition are considered. Historically, many deaf infants born to hearing parents have had little access to a conventional language. However, these children sometimes elaborate “home sign” systems. Lastly, the role of early experience in language acquisition is considered. Deaf children of hearing parents are immersed in a first language at varying ages, enabling a test of the critical-period hypothesis.