Brain and Language a Perspective from Sign Language

Properties of ASL The idea that sign languages are not a concatenation of universally understood pantomimes or concrete gestures has been hard to unroot. In fact, just as there are and Computational Sciences many spoken languages, there are many unique and Georgetown University different signed languages. Recent advances in linguis-Washington, DC 20007 tics have revealed that sign languages such as ASL † Psychology Department encompass the same abstract capabilities as spoken Washington University languages and contain all the different levels of linguistic Seattle, Washington 20007 representations found in spoken language, including Thus, similar linguistic structures are found in spoken and signed languages. A number of authors have pro-One of the most enduring and significant findings from posed that the left hemisphere recruitment for language results from a specialization of these areas for the analy-neuropsychology is the left hemisphere dominance for sis of linguistic structures. By this view, the structural language processing. Studies both past and present similarity between signed and spoken languages pre-converge to establish a widespread language network dicts that left hemisphere language areas should also in the left peri-sylvian cortex which encompasses at be recruited during ASL processing. least four main regions: Broca's area, within the inferior On the surface, however, ASL differs markedly from prefrontal cortex; Wernicke's area, within the posterior spoken languages. For example, in ASL, phonological two-thirds of the superior temporal lobe; the anterior distinctions are created by the positions and shape of portion of the superior temporal lobe; and the middle the hands relative to the body rather than by acoustic prefrontal cortex (Neville and Bavelier, 1998). While the features such as nasality and voicing found in spoken language processing abilities of the left hemisphere are languages. The fact that signed and spoken languages uncontroversial, little is known about the determinants rely on different input and output modalities carries im-of this left hemisphere specialization for language. Are portant consequences for theories on the origin of the these areas genetically determined to process linguistic left hemisphere dominance for language. It is often ar-information? To what extent is this organization influ-gued that the left hemisphere specialization for lan-enced by the language experience of each individual? guage originates from a left hemisphere advantage to What role does the acoustic structure of languages play execute fine temporal discrimination, such as the fast in this pattern of organization? acoustic processing required during speech perception To date, most of our …