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Effects of the Object’s Mass and Distance on the Location of Preferred Critical Boundary, Discomfort, and Muscle Activation during a Seated Reaching Task

Petrovic, Milena
http://rave.ohiolink.edu/etdc/view?acc_num=miami1343567265

Abstract Details

2012, Doctor of Philosophy, Miami University, Psychology.
When reaching for objects, actors have to determine the distance at which they will have to change from using one reach mode to another. This study examined the role of perceived discomfort and muscle activation in determining the distance of the preferred critical boundary (PCB) for seated reaching—the distance at which people actually transition between an arm-only and arm-and-torso reach modes. Participants pointed to a target placed at 10 distances using a power drill modified to three different weights (650g, 1000g,1350g). Discomfort ratings were obtained using a modification of Borg’s effort scale. Muscle activation was measured using surface electromyography (EMG integral per second and EMG maximum amplitude). The distance of the PCB decreased as a function of weight. Changes in the slopes of discomfort ratings for reaches at distances prior to and beyond the PCB indicated that change in discomfort is a determinant of the reach mode in each weight condition. Changes in the slopes of anterior deltoid, upper trapezius, and bicep activity at the PCB were also observed in each weight condition. Similar activation levels just prior to the PCB were observed for upper trapezius and ventral forearm group across the three weight conditions. Finally, two statistical models predicting the seated reach mode were created using the General Estimating Equation. Both models used intrinsic measures of distance (relative to arm length) and drill weight (relative to maximum grip strength). Two muscles were identified as strong predictors of seated reach mode: upper trapezius and ventral forearm muscle group.
Leonard Mark, PhD (Committee Chair)
William Berg, PhD (Committee Member)
Jay Smart, PhD (Committee Member)
Douglas Gardner, PhD (Committee Member)
91 p.
Psychology
Seated reaching; affordance; preferred critical boundary; discomfort; electromyography (integral and maximum amplitude); EMG; General Estimating Equation; GEE

Recommended Citations

Citations

  • Petrovic, M. (2012). Effects of the Object’s Mass and Distance on the Location of Preferred Critical Boundary, Discomfort, and Muscle Activation during a Seated Reaching Task [Doctoral dissertation, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1343567265

    APA Style (7th edition)

  • Petrovic, Milena. Effects of the Object’s Mass and Distance on the Location of Preferred Critical Boundary, Discomfort, and Muscle Activation during a Seated Reaching Task. 2012. Miami University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1343567265.

    MLA Style (8th edition)

  • Petrovic, Milena. "Effects of the Object’s Mass and Distance on the Location of Preferred Critical Boundary, Discomfort, and Muscle Activation during a Seated Reaching Task." Doctoral dissertation, Miami University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=miami1343567265

    Chicago Manual of Style (17th edition)

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© 2012, all rights reserved.
This open access ETD is published by Miami University and OhioLINK.