Sign Language: Psychological and Neural Aspects

Abstract

This article presents an overview of psychological and neural aspects of sign languages. A brief discussion of cultural and linguistic issues of deafness and the structure of American Sign Language (ASL) provide a framework to understand findings from developmental psychology, psycholinguistics, cognitive psychology and neuropsychological studies. Signed languages are naturally occurring human languages of deaf communities. Sign language acquisition follows a developmental trajectory similar to spoken languages. The recognition of a sign is influenced by the formational properties of sign language structure and occurs faster than spoken language recognition. While signs are articulated slower than spoken words, the proposition rate for sign and speech is the same. Memory for signs exhibits patterns of interference and forgetting that are similar to those found for speech. Studies of attention and perception indicate that the early use of sign language may enhance certain aspects of nonlanguage visual perception, such as the perception of motion. Neuropsychological and functional imaging studies show that left hemisphere regions are important in both sign and spoken language processing. Left hemisphere damage produces aphasia in signers. The existence of languages expressed in different modalities (i.e., oral–aural, manual–visual) provides a unique opportunity to explore and distinguish those properties shared by all human languages from those that arise in response to the modality in which the language is expressed.