Ascension's ReActor 2 is key to analysing human movements at Rutgers

Burlington 12 October 2004ReActor 2, Ascension's active-optical motion-capture system, is being used by Rutgers University to gather quantitative data on the visual perception of movement. For researchers there, ReActor 2 has quickly become a critical tool in exploring how visual experience, motor experience, and social processes all contribute to the visual analysis of human movement.


Led by Rutgers Psychology Department's Dr. Maggie Shiffrar and funded by the National Eye Institute, the research focuses on visual analysis of human action. "The goal of my research is to understand how the visual system interprets moving objects. To aid our understanding of visual system function, members of my laboratory examine the relationships between visual physiology and visual perception", stated Dr. Shiffrar.

Dr. Shiffrar chose ReActor 2 after searching and evaluating several systems. She liked it best because it presents no marker occlusion problems. "Since we are interested in whole body movements, we couldn't pick a system that fell apart every time a marker was hidden from a camera", Dr. Shiffrar explained. She also points out that because some of their studies involve people walking on treadmills, a magnetic tracking system might encounter interference from metals present in the treadmill.

ReActor's motion-capture cube enables Dr. Shiffrar's team to both project life-size displays on one side of the cube and then examine how people perceive the motion seen on the display. ReActor 2 performs two tasks: first its motion capture outputs provide the movies of human actions for the subjects to watch; secondly it measures the subjects' physical responses to those movies.

To measure these physical responses, Dr. Shiffrar's lab uses two different measurement techniques. "The first is a conscious measure", explained Dr. Shiffrar. "We ask people to make perceptual judgments such as How fast is that person walking? Is it a man or a woman? Is this the same person who you saw in the previous display?" The second measure is unconscious. Using the ReActor2 system, researchers measure how subjects unconsciously change their own movements in response to what they see.

For more information about ReActor 2 and other Ascension motion tracking products, you can visit the Ascension Web site or read the VMW October 2004 article Ascension to introduce breakthrough guidance device to European medical community. For more information about Rutgers University Psychology Department project, you can visit the Web site of Rutgers University.

Leslie Versweyveld

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