Visual memory for shapes in deaf signers and non-signers and in hearing signers and non-signers: Atypical lateralization and enhancement

Deaf and hearing individuals who either used sign language (signers) or not (nonsigners) were tested on visual memory for objects and shapes that were difficult to describe verbally with a same/different matching paradigm. The use of 4 groups was designed to permit a separation of effects related to sign language use (signers vs. nonsigners) and effects related to auditory deprivation (deaf vs. hearing). Forty deaf native signers and nonsigners and 51 hearing signers and nonsigners participated in the study. Signing individuals (both deaf and hearing) were more accurate than nonsigning individuals (deaf and hearing) at memorizing shapes. For the shape memory task but not the object task, deaf signers and nonsigners displayed right hemisphere (RH) advantage over the left hemisphere (LH). Conversely, both hearing groups displayed a memory advantage for shapes in the LH over the RH. Results indicate that enhanced memory performance for shapes in signers (deaf and hearing) stems from the visual skills acquired through sign language use and that deafness, irrespective of language background, leads to the use of a visually based strategy for memory of difficult-to-describe items.