Age related differences in left and right hand skill and in visuo-spatial performance: their possible relationships to the hypothesis that the right hemisphere ages more rapidly than the left.

Young and old right handed people were disproportionately worse with their left hand when speed was stressed but showed no especial difficulty when accuracy of performance was emphasised. Both groups of people were also tested on the AH4 test of cognitive abilities. As frequently reported by Rabbitt, the old were disproportionately worse on the visuo-spatial part than on the verbal part compared with the young, even though both parts required "fluid" abilities and even though both were given under time constraints. There was no correlation amongst the elderly people between speed stressed deficits in their left hand performance and their deficits on the visuo-spatial part of the AH4. Both fine control of the left hand and fingers and visuo-spatial performance are likely to be mediated by the right cerebral hemisphere and the implications of these results for a variety of possible views about selective aging of the right hemisphere are discussed.