Comparing different measures of laterality: do they relate to a single mechanism?

In the present study, a total of 126 adults were given three dichotic tasks, two half-field tasks, a peg-board task, several tapping tasks, the dynamometer, and a handedness questionnaire. A hierarchical cluster analysis was carried out on the matrix of product-moment correlations of laterality scores for all possible pairs of tasks. This analysis suggested that the laterality scores fall into three clusters: auditory (dichotic listening) scores, visual (half-field) scores, and manual (performance) scores. Canonical correlation analysis showed that these clusters must be considered to be independent of each other. The results are discussed with respect to the traditional interpretation of the concept of laterality. It is suggested that laterality phenomena may be dissociated and that this possibility deserves more attention.