Faster processing of visual transients in profound deaf individuals

Davide Bottari, Dipartimento di Scienze della Cognizione e della Formazione, Università di Trento, Italy

Abstract
Previous literature suggests that deaf individuals may show improved performance during attention demanding visual tasks compared to normal-hearings. These enhanced visual abilities were particularly observed at parafoveal and peripheral portions of the visual field. We compared 11 deaf individuals and 11 normal-hearings in a simple RT task, in which the sole attentional requirement was to divide attention across the visual field. One or two small squares appeared transiently for 50 ms at parafoveal (3 degree) or peripheral (8 degree) locations, along the diagonals of the computer display. Pair of stimuli always appeared at symmetrical positions with respect to fixation. Results showed that deaf participants were on average 45 ms faster than normal-hearings in all conditions (means 265 vs. 310 ms respectively). A redundant-target effect emerged for both groups (two stimuli faster than one). Unlike controls, deaf participants responded faster at parafoveal than peripheral locations. The results of this strikingly simple paradigm challenge previous interpretations underlying that enhanced visual abilities in the deaf emerge selectively under condition of focused attention. In addition, they suggest that the faster processing of visual transient need to be taken into account when interpreting enhanced performance in this sensory deprived population.

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