The effect of age on hemispheric asymmetry in visual and auditory identification

On psychometric tests, spatial scores typically decline more with age than do verbal scores. Since in humans, visuo-spatial information is more efficiently processed by the right hemisphere (RH) and verbal information by the left (LH), this behavioral pattern could reflect a greater age decline in RH than in LH abilities. To test this possibility, the speed with which young and old subjects identified stimuli in their right and left visual fields was measured. Since each half field, projects to the opposite hemisphere, by presenting stimuli in one half field, RH and LH abilities can be measured relatively independently. Words were identified faster in the right field (i.e., LH), pictorial stimuli in the left (RH). This was equally true for both young and old. Similarly, a right ear advantage in the identification of dichotically presented syllables was of equal magnitude in both age groups. Thus, there was no evidence on these tasks for a selective decline with age in RH processing efficiency.