[Selective interference of a motor task on the reaction time to stimuli presented to the visual field of the left...

Simple reaction time to a lateralized visual stimulus was studied in normal subjects while they were carrying out a concomitant task. The concomitant task consisted in a flexion of a single finger or pairs of finger at the middle joint. Regardless of the hand used the concomitant tasks produced a specific lengthening of responses to stimuli located in the left visual field. It is concluded that isolated finger movements, separate from a sequence of movement, are function of the right hemisphere.