Theory and practice in the measurement of laterality

Using data from a divided visual field task, it is shown that correlations between laterality measures and overall accuracy are not a consequence of the level of accuracy constraining the achievable range of laterality, but depend on the design of current laterality measures and on the differential correlation of each hemisphere's scores with total accuracy. Comparing four laterality measures on 125 subjects shows that, although the laterality distributions differ in dispersion, the four measures are significantly intercorrelated and give nearly identical indications of average lateralisation. It is concluded that laterality measures may be of some limited use in comparing experimental results from different sources rather than in evaluating theories of cerebral asymmetry.