INSTABILITY IN FUNCTIONAL MOTOR LATERALITY OF CHILDREN AND ADOLESCENTS WITH ENDOGENOUS PSYCHOSIS AND PREDOMINANTLY MOTOR DISTURBANCES

A group of eight unmedicated right-handed children and adolescents wit h endogenous psychosis and predominantly motor disturbances and two ri ght-handed control groups (6 healthy subjects and 10 patients with dif ferent psychiatric diseases) were investigated with the help of a tapp ing-test series. The most important finding was related to differences in the stability of functional motor laterality between controls and psychotics. Stability or instability in functional motor laterality wa s identified by referring to the standard deviation (SD) of percentile right-left tapping differences calculated for each subject for the va rious parts of the tapping-test series. The high SDs in psychotics, in contrast to the low SDs in both control groups, point to increased va riations or instabilities in the functional superiority of the preferr ed hand. Instability in functional motor laterality in this test is co nsidered characteristic of this subgroup of patients, and may be due t o a partial relapse to a lower hierarchical stage of handedness.