Lateral preferences in the monkey.

The hand preferences of 28 monkeys were recorded on two visual discrimination tasks. A higher incidence of left than right preferences was expected throughout visual training (whereas this ratio decreases and approaches unity during tactile training). As expected, there was less decrease during visual training than tactile training of the proportion of left preferences within tasks; but across tasks, in conflict with the expectation, changes from left to right preferences occurred more frequently with visual than tactile training.