Handedness, limb selection, and reach control: a test of the dynamic dominance hypothesis

Handedness, Limb Selection, and Reach Control: A Test of the Dynamic Dominance Hypothesis. (December 2008) Won Dae Kim, B.S., Seoul National University; M.S., Seoul National University Chair of Advisory Committee: Dr. Carl Gabbard This study examined the generalization of the Dynamic Dominance Hypothesis (DDH) in regard to limb dominance, limb selection, and limb action. This study was inspired by the finding that limb selection changes from dominant-arm to nondominantarm occur around an object position of 80° for right-handers and 100° for left-handers after passing the body midline (90°) into contralateral hemispace. For Study 1 and Study 2, 10 right-handed and 10 left-handed adults participated and reaching with the right and left arms of rightand left-handers was made to each of nine targets using free-choice and forced-choice paradigms. The purpose of Study 1 was to determine the relationship between limb selection and the DDH among both handedness groups. Thus, Study 1 addressed the following questions: Can the DDH explain why people select their nondominant hand for reaching into their contalateral hemispace? Do predictions of the DDH hold for rightand left-handers? Our results suggest that control efficiency with regard to a reduction in degrees of freedom in reaching movements seems to be a more fundamental cause for the limb selection