The relationship between reaction times and hand and foot laterality in the slightly mentally handicapped.

The study was carried out on 16 normal children and 16 slightly mentally handicapped children aged 9 years and 10 months. We studied: simple reaction time and simple and complex choice reaction time for the hand and foot. Hand and foot lateralities were determined using six tests. This study enabled us to show different elements: Hand and foot laterality is less often confirmed among the handicapped children. For both groups the fastest hand and foot simple reaction times do not indicate the preferred limb. The possibility of choice in the case of the hand considerably delays the reaction times for the handicapped children. This tendency is not confirmed in the case of choice reaction times for the foot, where the handicapped children are not significantly slower than the normal children, in a choice situation. If the choice situation becomes complicated the handicapped children are slower than the normal children. With the normal children simple reaction times are slower for the foot than for the hand. However, the handicapped children do not show a significant difference between hand and foot reaction times. We put forward the theory that this fact could be explained by the different form of the motor response. Handicapped children have greater difficulty in integrating precision and speed of movement, factors which occur in the movement of the hand reaction time but not in the movement of the foot reaction time.