Left-handedness and cognitive deficit.

Intellectual and performance measures were taken on 7688 school children tested on three behavioral measures of handedness and one measure of eyedness. Test results were compared against all combinations of handedness and eyedness and against a measure of socio-economic level. No relationships of any kind were found. Comparisons of the present results are made against 33 studies concerned with possible deficits associated with left-handedness. The results of the present study combined with a review of the majority of studies on deficit and handedness strongly suggest that the hypothesis of no difference in intellectual and cognitive performance between right- and left-handed subjects can be accepted as true.