New Research Reveals Secrets of 'Third Order' Pure Color Motion Detection Sytem Used by Brain
How can a brightly colored and striped tiger be so hard to see moving in jungle shadows?
Part of the explanation may be found in new research from the University of Southern California and the University of California, Irvine.
According to USC experimental psychologist Zhong-Lin Lu, research in neurophysiology has discovered two independent brain pathways for visual information in the brain. One pathway is sensitive to color but not sensitive to motion; the other is sensitive to motion but not sensitive to color.
Integration of color and motion information is therefore vital to detect the camouflage of the moving tiger. Humans can, in fact, perceive motion from "isoluminant" images, which contain different colors with the same brightness, like those of a big cat moving through dappled shadows. But they only do so by a less sensitive mechanism than is used detecting motion using brightness or texture cues.
Dr. Lu says his team's new set of studies has unraveled how this less sensitive system works, and what its limitations are in perceiving motion by isoluminant objects. An account of their experiments appears in the July 6 edition of the Proceedings of the National Academy of Science of USA.
According to Lu, an assistant professor of psychology in the USC College of Letters, Arts and Sciences, researchers have found that human motion perception is served by three parallel brain mechanisms. These include an extremely sensitive "first order" system that depends on cues from varying brightness, a slightly less sensitive "second order" system that depends on cues from texture, and a highly versatile but considerably less sensitive "third order" system that depends on figure-ground contrast.
The series of recent experiments confirms that motion is detected in pure,
isoluminant color only by the third-order, figure-ground system.
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Contact: Eric Mankin
mankin@usc.edu
213 740 9344
University of Southern California
5-Jul-1999