Cerebral asymmetry for verbal information in severe aphasia.

Reaction times (rt's) of 3 M and 6 F Ss aged 57-84 yrs (mn = 69 yrs) with severe Broca's aphasia and of 9 normal matched Ss were measured to taped verbal stimuli (12 word-pairs posing minimal phonemic contrasts; half the contrasts were prevocalic, half postvocalic. Identical words were presented monotically to both ears; difference in manual rt to pictures of these words was taken to indicate ear advantage). The aphasics had limited but reliable auditory comprehension and minimal speech; they evidenced L-ear advantage in rt's although the postvocalic rt as compared with prevocalic rt was normal. These results were interpreted as indicating a latent R-brain linguistic capacity which emerged after significant L-brain damage.