Sean Barton Ryan Hope, Graduate Students


Sean Barton Ryan Hope, Graduate Students

Sage 4101

December 4, 2013 12:00 PM - 1:30 PM

​Ryan Hope

Title:   Eye movement optimization in visual search


In the present study we investigated whether eye movements in visual search are optimized to reduce time on task. Subjects task was to find a target object in a large field of objects that differed based on shape, color, size and numeric label. The target specification was manipulated, directly influencing the average number of fixations it took subjects to find the target object. Although a microstrategy that allowed for parallel saccade programming and information processing was found to be more efficient in terms of time, a serial microstrategy where saccade programming always follows information processing was found to be the more prevalent microstrategy.


Eye movement optimization in visual search



Sean Barton

Title:  Title: Exploiting Motor Redundancy


The human motor system has more dimensions along which it can vary than are strictly required by tasks in our day-to-day lives. This excess of dimensions creates redundancy in the movements and configurations of the motor system, such that there can exist multiple motor solutions for a given task. Redundancy is a source of computational complexity, but it is also an important asset that can provide stability and flexibility in action. However, how people learn to utilize available redundancy is not well understood. We have adapted an experimental paradigm designed by Mosier and colleagues (Journal of Neurophysiology, 2005) to investigate how the exploitation of motor redundancy is learned for novel motor problems. Using a full-body motion capture system, six arm joints were mapped onto the control of a cursor in a 2D virtual environment. Participants moved the cursor between target locations while passing through a fixed, centralized waypoint. The redundant nature of the motor-control problem provided opportunity for participants to vary arm posture at the waypoint depending on their point of origin and desired target. Postures at the waypoint were projected into effective and redundant space to determine if changes in the distribution of joint variability were consistent with redundancy exploitation. Posture variability at the waypoint decreased with practice, both in effective and redundant dimensions, suggesting that participants stereotyped postures regardless of starting location or intended target. We also examined whether posture at the waypoint could be used to classify participants' intended targets. Classification accuracy for intended target and point of origin was near chance. These findings suggest that the availability of motor redundancy alone may not be sufficient for developing redundancy exploitation strategies.

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