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Gaze and Gait

How do we learn and execute new movement plans?

Gaze and

movement planning

Whether you are shooting a basketball or learning to walk, you must be able to effectively plan a movement before you can execute it. That planning is reliant on your eyes, specifically where you look and when you look there. 

 

My PhD research focused on gaze behavior during motor learning in order to better understand the role of gaze in providing relevant information while learning new walking patterns.

Gaze Behavior Changes with Walking Difficulty

The core motivation for my PhD started with the understanding that where we look and how we use vision changes with permanent changes to our walking ability. States like aging, injury, or elite athleticism all changed where people direct their vision and how they rely on their vision to safely move.

It made me curious about how these differences come to be, and does training vision offer an opportunity to improve walking?

Comparing Gaze Behavior
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Practicing Walking Increases Fixation Distance

In an initial study, participants practiced walking on projected targets. As expected, as they improved, they looked farther ahead.

Scroll through on the right to see some of the results.

Despite looking farther ahead, people rely on near information more with practice

While where people look is one measure, how much they rely on information is another. While these may align, they do not have to and in this second study, we find that they don't.

Specifically, by strategically removing parts of participants visual fields, we can measure how important that information was by how much their performance drops.

Read the Paper
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Top: Participants walked on the treadmill while targets (yellow rectangles) were projected down. We tracked where they looked (orange dots) along with where their feet were (red and blue diamonds) to calculate step error and fixation distance.

Bottom: Plot representing some of the raw data with time across the x axis and Forward/Backwards position (relative to the participant) on the y axis.

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Targets dropped from the top of the game screen while participants had to press the appropriate key when the target hit the bottom. As with walking, the targets were occasionally hidden to probe participant's visual reliance.

Are the effects specific to walking?

The Pandemic Pivot

As an extension of the walking work, and as a way to make progress while everything was remote, I developed an online version of my task inspired by guitar hero.

By applying similar logic, and assuming the changes are driven by a general visuo-motor connection rather than specific to walking we would expect the same effects. Instead, we see visual reliance disappear with practice!

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Applying the learnings to Concussion

One application of alot of this work is to improve rehabilitation practices for people who struggle with motor control. The population I started with are people post concussion, who often have both motor and visual deficits that can persist, hidden, beyond the return to play point.

While good in theory, my first experiments did not find any difference between people with concussion and healthy controls on any of the metrics from my earlier experiments.

Next steps may be to change the experiment or to focus on other possible connection points, such as deficits in proprioception.

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First things first, people are able to improve their step accuracy with practice

A Meta Look

One benefit of having consistent metrics across my dissertation is that we can reasonably compile the results across all the studies to look at overall trends

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Read

Want to see the complete story? you can read my complete dissertation here.

Read the Dissertation
Image by Dom Fou

Watch

Rather watch me explain it? You can watch my recorded public defense here

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