Deafness and Attentional Visual Search: A Developmental Study

Neurophysiological (epigenetic specialisation of cortical areas) as well as behavioural (sign language, visual control of spatial surroundings) constraints suggest that deaf people should develop heightened abilities of processing parafoveal/peripheral visual information. Electrophysiological (visual event-related potentials) and psychophysical research using visual detection tasks on congenitally deaf adults corroborates this viewpoint (Neville, 1994 The Cognitive Neurosciences 219 – 231). The aim of this study was to examine whether this ability remains when the visual detection task requires a spatiotemporal organisation of attention.

Forty congenitally bilaterally deaf (from a specialised institution) and sixty-four hearing subjects, subdivided into five age groups (from 7 years of age to young adults) performed four visual search tasks. The results showed that the younger deaf children performed dramatically worse than the aged-matched hearing children. This difference in performance between deaf and hearing children, however, disappeared at an age level of 11 years. Deaf adults did not perform significantly better than hearing adults. The data obtained in children have been replicated in a longitudinal study (re-test two years after). We are currently trying to determine which attentional mechanisms are more deficient in young deaf children (spatiotemporal organisation of search, engagement/disengagement of attention, etc) and what underlies the apparent amelioration of their deficit during development.