PROCESSING A DYNAMIC VISUAL-SPATIAL LANGUAGE - PSYCHOLINGUISTIC STUDIES OF AMERICAN SIGN LANGUAGE

American Sign Language (ASL) has evolved within a completely different biological medium, using the hands and face rather than the vocal tra ct and perceived by eye rather than by ear. The research reviewed in t his article addresses the consequences of this different modality for language processing, linguistic structure, and spatial cognition. Lang uage modality appears to affect aspects of lexical recognition and the nature of the grammatical form used for reference. Select aspects of nonlinguistic spatial cognition (visual imagery and face discriminatio n) appear to be enhanced in deaf and hearing ASL signers. It is hypoth esized that this enhancement is due to experience with a visual-spatia l language and is tied to specific linguistic processing requirements (interpretation of grammatical facial expression, perspective transfor mations, and the use of topographic classifiers). In addition, adult d eaf signers differ in the age at which they were first exposed to ASL during childhood the effect of late acquisition of language on linguis tic processing is investigated in several studies. The results show se lective effects of late exposure to ASL on language processing, indepe ndent of grammatical knowledge.