Repetitive behavior and repetition avoidance: the role of the right hemisphere.

Based on clinical observations of patients suffering from brain damage, a recent model assumes a right hemisphere dominance for the suppression of repetitive behavior. This study set out to test whether or not the well-known effect of repetition avoidance in sequential response production is likewise mediated by the right hemisphere. It was found that, in 40 healthy subjects, avoidance of repetitions in a random number-generation task correlated positively with a relative superiority for design as compared to letter fluency. Since design fluency is predominantly mediated by the right frontal lobe and letter fluency by the left, this finding supports the notion of a right hemisphere dominance for the avoidance of repetitive responses. This study illustrates the usefulness of a neurobehavioral approach to repetition behavior in the randomization of response. In particular, it demonstrates that the phenomenon of repetition avoidance may be better accounted for in terms of a control mechanism preventing perservation than by referring to human subjects' "generally biased concept of randomness."