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

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Title: Handedness, limb selection, and reach control: a test of the dynamic dominance hypothesis
Author: Kim, Won Dae
Abstract: 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 nondominant -arm 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 right - and 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 right - and 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 phenomenon rather than the DDH . Also , our data reveal that kinematic differences between right - and left -handers with regard to utilization of joints for reaching explain limb selection differences between both handedness groups . The aim of Study 2 was to extend generalization of the DDH using a wide range of movement speed . Thus , Study 2 addressed the following question : Do propositions of the DDH hold for a wide range of speeds ? Our data indicate the DDH does not hold for either slow or fast speed in reaching movements . Rather , a change in kinematics with regard to utilization of joints in reaching movements is associated with movement speed . Considered together , our data indicate that the DDH is an inadequate explanation of differences in limb selection , limb dominance (handedness ) , and limb action (speed ) . Rather , our findings with regard to control efficiency seem to be more fundamental and justified explanations for limb differences in the control of reaching based on the context of our task .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -3183
Date: 2009-05-15

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Handedness, limb selection, and reach control: a test of the dynamic dominance hypothesis. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -3183 .

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