Processing biases towards the preferred hand: valid and invalid cueing of left- versus right-hand movements.

A Posner-like paradigm was employed to investigate the effects of valid and invalid cueing of each hand on reaction time, movement time and peak velocity in an aiming task. Given claims of left hemisphere superiority in movement selection and inhibition (and the privileged within-hemisphere access of the right hand to such systems), it was hypothesised that invalidly cueing the left hand (i.e. right-hand movement precued, left-handed movement required by a go signal) would result in increased reaction time relative to invalid right-hand cueing. The hypothesis was not confirmed as reaction times of both hands were slowed equivalently by invalid cueing. Nevertheless, it was found that the movement duration of the left hand was increased substantially by invalid cueing, while the right hand was unaffected on this measure, suggesting a possible intentional rather than attentional difference between the two hands. These results are discussed in terms of a possible asymmetry of intentional processes related to hand movement and the right-hand advantage in movement duration.