[Functional asymmetry of monkeys' hand movements (Macaca mulatta)]

Three Macaca mulatta were tested in two different tasks. In the naturalistic behavioral experiment, a monkey had to grasp a piece of food from a hollow cube with an asymmetric position of an aperture. The preferable hand was determined. In the second experiment, a monkey performed a more difficult instrumental task: it pulled the lever by the right or by the left hand depending on the position of a trigger stimulus in a corresponding visual hemifield. It was shown that, in the second task, the preferable hand to some extent is characterized by the following: 1) it was mainly used if the trigger stimulus was presented in the contralateral midline region of the visual field, 2) shorter latencies, 3) higher maximum speed of the movement. On the basis of the results obtained a hand preference criterion can be developed in monkey laboratory experiments.