A comparison of deaf, normal, and brain damaged adults on a tachistoscopic task

Printed words and letters, pictures of signed words, and pictures of finger-spelled letters were presented tachistoscopically to deaf, normal, and brain-damaged adults. The findings suggest that (1) the deaf show no cerebral asymmetry for any of the material but found identification of the stimuli very difficult unless a forced-choice recognition procedure was used or the exposure time was very long; (2) both the normal and the brain-damaged groups show left hemisphere superiority for printed material but no cerebral specialization for signed material; (3) the left-right hemisphere difference is more marked in the brain-damaged group regardless of which hemisphere showed most damage. This may be explained, at least in some cases, by impaired transfer across the corpus callosum.