Effect of visual presentation format and recall direction on letter span and error patterns in Deaf signing and hearing adults.

Abstract

Deaf signers consistently show shorter memory spans than hearing nonsigners, but the scope and nature of this difference remain unclear. The present study tested whether Deaf signers are biased toward flexible use of visual aspects of linguistic items. Matched samples of adult Deaf signers (N = 33) and hearing nonsigners (N = 32) performed a letter-span task with visual serial presentation, to bias phonological processing, and a simultaneous presentation, to bias visuospatial processing. We also manipulated short-term memory by varying recall direction (forward, backward). Analyses revealed reduced spans for Deaf signers compared with hearing nonsigners, backward compared with forward recall, and sequential compared with simultaneous presentation. Item-level responses indicated that Deaf signers made more errors than hearing nonsigners across three error types. Deaf signers also showed reduced item position binding compared with hearing nonsigners, which indicates differences related to item order and sequencing in tasks with printed, linguistic stimuli. Deaf signers were the only group who demonstrated reduced omission errors when switching from sequential to simultaneous presentation, suggesting flexible processing mechanisms. No group differences were found for a secondary spatial span test, indicating the scope of group differences for ordered information was limited to verbal items. Overall, results are consistent with flexible use of different memory cues in Deaf signers. A core area for future research includes evaluating reduced activation of phonological representations of linguistic items in Deaf signers. These results amplify a novel M3 model approach for evaluating how errors contribute to short-term memory differences in Deaf signers.