The relationship between leftward turning bias and visuospatial ability in humans

A significant relationship was found between a bias to make complete counter-clockwise (leftward) turns and performance levels on tests of visuospatial function. Subjects who turned preferentially to the left over a four-day period performed above average on visuospatial tests with those having the greatest turning bias performing the best. Subjects who tended to turn to the right performed below average on tests of visuospatial function. There was no relationship between rotational bias and verbosequential skills, but there was a significant relationship between turning bias and a cognitive profile defined as the difference between visuospatial ability and verbosequential ability. The cognitive profile effectively partialed out overall ability suggesting that the turning bias is related to the bias for better visuospatial processing rather than the level of visuospatial performance per se. Asymmetric turning has been shown to be related to asymmetries of dopamine activity in rats. Therefore, the present results are discussed in relation to the possibility that the dopamine neurotransmitter system may underlie both rotational behavior and visuospatial cognitive function in humans.