Processes used in working memory and reading by deaf and hearing ASL signers and hearing non-signers

In general, deaf individuals read with more difficulty than hearing individuals, suggesting that the deaf may have difficulty using a speech-based code for processing information or recalling ordered information implicit in the syntax of the English language (Hanson, 1982). In two experiments, the short-term processing of written and signed information was investigated in hearing non-signers and deaf and hearing signers during reading and memory span tasks under conditions of no, oral, and manual articulatory suppression. In Experiment 1, participants saw passages of words and signs and tried to detect the words or signs that did not make sense within the context of a sentence. In Experiment 2, they recalled, both serially and freely, lists of phonologically similar and dissimilar words as well as formationally similar and dissimilar signs. Results of Experiment 1 showed that hearing participants (signers and non-signers) had higher d' scores for error detection than deaf participants in text passages but not in signed passages (hearing signers). Neither oral nor manual suppression reduced the d' scores for error detection in the text passages; however, oral suppression reduced d' scores for error detection in the signed passages overall. In Experiment 2, hearing participants had larger memory spans than deaf participants in serial but not free recall. All participants showed a phonological similarity effect in both serial and free recall as well as a reduction in memory-span for words during oral suppression. Only hearing participants showed a reduction in the phonological similarity effect during oral suppression. There was a formational similarity effect in serial recall for deaf signers as well as a reduction in memory-span for signs in free recall during oral suppression for all signers and during manual suppression for hearing signers. These results suggest that signing participants were using both speech- and sign-based codes for processing information and the strategy used depended on the task requirements.