Response Selection Contributes to the Preparation Cost for Bimanual Asymmetric Movements

ABSTRACT

Movement preparation of bimanual asymmetric movements takes more time than bimanual symmetric movements in choice reaction-time conditions. This bimanual asymmetric cost may be caused by increased processing demands on any stage of movement preparation. The authors tested the contributions of each stage of movement preparation to the asymmetric cost by using the additive factors method. This involved altering the stimulus contrast, response compatibility, and response complexity. These manipulations changed the processing demands on stimulus identification, response selection, and response programming, respectively. Any manipulation with a larger reaction time cost than control suggests that stage contributes to the bimanual asymmetric cost. The bimanual asymmetric cost was larger for incompatible stimuli, which supports that response selection contributes to the bimanual asymmetric cost.

Keywords:

• additive factors method
• bimanual reaching movements
• direct cues
• information processing

ACKNOWLEDGMENTS

The authors thank Professor Robert L. Sainburg and an anonymous reviewer for their insightful critiques. The Natural Sciences and Engineering Research Council of Canada supported this research with a discovery grant awarded to Romeo Chua.