Perks of blindness: Enhanced verbal memory span in blind over sighted adults

Blind individuals commonly use verbal encoding (i.e. text-to-speech) and memory-based strategies (i.e. serial recall) for situations in which sighted individuals use vision (i.e. finding items). These strategies may serve to train cognitive systems responsible for maintaining and manipulating verbal information. To test this hypothesis, we investigate whether early visual deprivation is linked to improved verbal short-term and working memory abilities, and thus might illustrate experience-dependent plasticity in memory systems. We also test whether the sensory modality for encoding information influences performance. Our data show that blind adults recalled more items on a verbal short-term memory span task than sighted participants. Furthermore, blind individuals performed equally well on auditory forward and backward conditions despite the fact that recalling items in reverse order is more difficult for the general population. However, the benefits of recalling items in reverse order did not extend to the tactile domain, specifically, a braille version of the short-term memory digit span task in blind individuals. Furthermore, we observed no differences between blind and sighted individuals on a more demanding auditory n-back task evaluating more complex working memory processes. We conclude that the memory benefits associated with blindness might be restricted to auditory-verbal short-term memory and likely reflect strategy use and practice.