Spatial task demands affect the extent of manual asymmetries.

The degree of hand preference and the magnitude of hand differences in performance are thought to relate to skill level. The purpose of the experiments discussed here was to examine the effect of skill as reflected in the spatial precision demands of a movement, on the extent of manual asymmetries. Experiment 1 utilised the Annett pegboard, and manipulated spatial precision by varying peg diameter. The second experiment utilised the Grooved pegboard, and manipulated spatial precision by altering the size of the target hole. Analyses revealed that movement time increased as a function of the increased spatial precision demands. Although the preferred hand was always faster, the magnitude of this advantage was only affected in Experiment 2, in which the manipulation of spatial precision was maximal. The implications of these findings for the skill interpretation of handedness are discussed.