Spatial compatibility effects with unimanual and bimanual wheel-rotation responses: an homage to guiard (1983).

Y. Guiard (1983) reported a prescient study of compatibility effects in response times for clockwise/counterclockwise wheel rotations to stimuli in left/right locations. Left-right coding of responses predominated in his study, but some results suggested that unimanual versus bimanual operation was also a factor. The authors report 3 experiments directly examining whether there is a difference in spatial compatibility effects obtained with wheel-rotation responses executed bimanually or unimanually (with left or right hand). Adopting a right-to-clockwise or left-to-counterclockwise mapping was advantageous for top, side, and bottom hand placements. This benefit interacted neither with unimanual or bimanual responding nor with the response hand. The results confirm that the critical relation is between the wheel and stimulus position, and is not effector dependent. This finding is in agreement with results from studies using discrete keypress responses, emphasizing that spatial coding of stimuli, actions, and their goals is of central importance in response-selection decisions.