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Date of Award


Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy in Applied Cognitive Science and Human Factors (PhD)

Administrative Home Department

Department of Cognitive and Learning Sciences

Advisor 1

Kevin Trewartha

Committee Member 1

Carolyn Duncan

Committee Member 2

Kelly Steelman

Committee Member 3

Robert West


Making online movement corrections is an important part of navigating dynamic environments where unexpected obstructions can occur. Failure to engage in these corrections can result in injury and, in some cases, death. Observations of movement corrections demonstrate that younger adults tend to follow the minimal intervention principle when correcting their movements. The objective of the current work is to study differences in how older and young adults make online movement corrections and explore the cognitive and physiological contributors to successful online movement corrections. Experiment 1 shows older adults are as likely as young adults to choose hand paths that require the least effort following a visual perturbation; however, they also commit more collisions and have slower movement speeds. Regression analyses show success rates and movement times on the obstacle avoidance task are related to measures of executive control and processing speed. Additionally, perturbations elicited P3b components often associated with executive control. These ERP responses were different following medium and large perturbations for young adults; however, they were not different for older adults. Experiment 2 shows that whether responding to visual or haptic/proprioceptive feedback impacted young adults’ obstacle avoidance performance when the optimal path was ambiguous. P3bs observed in Experiment 2 were also affected by the difference in the modality of feedback. When these findings are evaluated with the experiment’s other findings showing 1) greater P3b related activity for collision trials than non-collision trials, 2) very little differences between P3bs from trials with inward and outward movement corrections, and 3) EMG indicators of movement correction onset occur before the P3b peak, it suggests that the neural activity observed in this study has more to do with monitoring the movement corrections than path selection. The regression models from Experiment 2 also show the top-down processing of visual feedback is associated with a greater number of cognitive variables; yet some level of executive control is still associated with participants' tendency to make optimal reaching movements following physical perturbations.