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5 December 2013 11:26 am ,
Vol. 342 ,
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
- About Us
Going With the Optic Flow
30 January 2001 7:00 pm
James Bond is racing his armor-plated Aston Martin along a mountain road, swerving wildly and trying to reach a narrow tunnel. Does he make it? New research suggests that if he succeeds, it's due to two strategies: Keeping his eye on the target, and watching how the guardrails whiz past. The research could eventually lead to a better understanding of visual impairments that affect mobility, and may help robots get around more easily.
Scientists have two theories for how people steer toward a target. You can simply fix your eyes on it, aim your body, and go. Or you can align your steps to the moving pattern that flashes across your retina as you walk. (If you're a Star Trek fan, think of this so-called optic flow as the blur of stars as the Enterprise jumps into warp drive.) But since both approaches get you to the same goal, scientists haven't been able to tease them apart.
In an experimental breakthrough, cognitive scientist William Warren of Brown University in Providence, Rhode Island, created a virtual reality system that allows him to separate the two strategies. He and his colleagues asked subjects to walk toward a virtual doorway and presented them with an artificial optic flow pattern that was shifted slightly away from their walking direction. If subjects used the shifted optic flow to take aim, the team predicted, they would miss the door. If they relied only on the visual direction of the door, they would head right toward it.
As it turned out, the importance of optic flow depended on its amount. When the virtual scenes contained only the doorway, subjects had no trouble heading straight for it. But when the doorway's optic flow was enhanced with whizzing objects such as posts and textured floors, subjects ended up steering away from the door.
The research, reported in the 1 February issue of Nature Neuroscience, is "undoubtedly a step forward," says John Wann of the University of Reading in the United Kingdom. "It's been difficult to create simulations where you could control optic flow and heading information." Now, says Wann, the question is how humans switch between the kinds of information they use to choose their direction.