UW Eye Research Institute
In her laboratory, Mason has created a computerized virtual environment dubbed “The Wisconsin Collaborative Virtual Environment (WiscCVE)” to simulate specific tasks, allowing her to manipulate the type and timing of sensory feedback that a test subject receives. Sitting at a mirror-topped table, the test subject wears polarized stereoscopic goggles, much like sunglasses, that give the subject the sensation of viewing a three-dimensional object that is positioned on the table surface. The subject also wears light emitting diodes (LEDs) on the first finger and thumb of each hand, and when viewed in the virtual environment these LEDs appear as dots that show the placement of the fingers. During testing, Mason can turn on or turn off the subjects’ view of the dots, giving them just a glimpse of their fingers or hiding them from view entirely. In a typical experiment, the subjects are shown a cube in the virtual environment, and are asked to move their fingers toward the cube, grasping it when they are able.
Following a stroke, patients must re-learn basic tasks involving hand-eye coordination, like grasping a pen to write or draw.
“I can alter the point at which the subjects see their fingers or see the cube. We can then assess the importance of the visual feedback on the ability of the subjects to grasp the object,” Mason explains. “Is it better to have feedback at the beginning of the task or at the end? Does the feedback need to be continuously present from the start to the end of the task, or can it drop out once the reach is initiated?”
Mason expected that knowing where one’s fingers were positioned at the beginning of the task would not be as important as the ability to see the hand as it approached the cube. Surprisingly, she found that the opposite was true – when subjects had visual feedback only toward the end of the movement, their performance was as bad as when they got no feedback at all. “It turned out that if feedback about the finger position was given only in the first third of the movement, the speed at which the person performed the task was the same as if they could see their fingers the entire time.”
These types of experiments help Mason learn about how sensory feedback affects performance in virtual environments. Mason explains, “If we can discover what type of sensory information is needed and when that information is used, we can make recommendations about how and when to display sensory information to users of virtual environments.” The virtual environments that Mason’s studies may help to improve are not the entertainment-oriented video games. Instead, she sees potential applications in more “work-related” environments such as robotic surgery or virtual architectural walk-throughs. Mason is currently planning a project that would use findings from her work in both natural and virtual environments to develop an at-home rehabilitation system for survivors of stroke. This at-home “virtual training system” would allow patients to continue rehabilitation in an exciting and stimulating computerized environment after traditional clinic rehabilitation has ceased. “Some research has indicated that rehabilitation in virtual environments may be superior to traditional rehabilitation because it is more engaging and may lead to greater adherence. We would like to help patients develop better strategies to manipulate objects in their environment following a stroke. We hope that the results of our work will lead to a cost-effective and engaging training system that people could use in their own homes.”
Mason is also interested in understanding more about how people use sensory information, like vision, to coordinate the movement of the two hands as we grasp separate objects simultaneously. People do tasks like this many times a day in normal life. For example, a writer reaches for a pen with one hand while simultaneously reaching for the paper with the other. In recent studies of adults and children, Mason investigated the timing of the coordination of two simultaneous movements such as these, and assessed how certain sensory demands affected this coordination. (Next)(Previous)