Verbal and visual serial-order memory in deaf signers and hearing nonsigners: A systematic review and meta-analysis.

Abstract

Previous research suggests Deaf signers may have different short-term and working memory processes compared with hearing nonsigners due to prolonged auditory deprivation. The direction and magnitude of these reported differences, however, are variable and dependent on memory modality (e.g., visual, verbal), stimulus type, and research design. These discrepancies have made consensus difficult to reach which, in turn, slows progress in areas such as education, medical decision-making, and cognitive sciences. The present systematic review and meta-analysis included 35 studies (N = 1,701 participants) that examined verbal (n = 15), visuospatial (n = 10), or both verbal and visuospatial (n = 10) serial-memory tasks comparing nonimplanted, Deaf signers to hearing nonsigners across the life span. Multivariate meta-analyses indicated a significant, negative effect of deafness on verbal short-term memory (forward recall), g = -1.33, SE = 0.17, p < .001, 95% CI [-1.68, -0.98], and working memory (backward recall), g = -0.66, SE = 0.11, p < .001, 95% CI [-0.89, -0.45], but no significant effect of deafness on visuospatial short-term memory, g = -0.055, SE = 0.17, p = 0.75, 95% CI [-0.39, 0.28]. Visuospatial working memory was not analyzed due to limited power. Population estimates for verbal and visuospatial short-term memory were moderated by age wherein studies with adults demonstrated a stronger hearing advantage than studies with children/adolescents. Quality estimates indicated most studies were of fair quality, with only 38% of studies involving Deaf authors. Findings are discussed in the context of both Deaf equity and models of serial memory.