EFFECTS OF FOVEAL STIMULATION ON PERIPHERAL VISUAL PROCESSING AND LATERALITY IN DEAF AND HEARING SUBJECTS

This research examines visual field differences in the detection and i dentification of a peripheral stimulus for deaf and hearing subjects, as a function of concurrent foveal stimulation. Deaf and hearing subje cts were presented with peripheral target stimuli (simple geometric sh apes) presented tachistoscopically to the left or right visual fields under four conditions of foveal stimulation: (a) no stimulus; (b) simp le geometric shapes; (c) pictorial shapes (outline drawings); and (d) orthographic letters. Dependent measures were detection response laten cy and peripheral shape recognition (errors). With error data, hearing subjects showed a right field advantage under foveal conditions of no stimulus and simple shape stimulus, but a left field advantage with p ictorial and letter foveal stimuli. Deaf subjects showed the opposite effect, with a left field advantage under foveal conditions of no stim ulus and simple shape stimulus, but a right field advantage with picto rial and letter foveal stimuli. Latency data revealed the same pattern of results for hearing subjects, but no significant visual field diff erences for deaf subjects. Results are interpreted in terms of differe nces in hemispheric visual processing used by deaf and hearing subject s, as affected by varying conditions of foveal load.