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On the right track

发布时间:2019-03-08 08:15:22来源:未知点击:

By Jonathan Knight in Princeville, Hawaii FOLLOWING moving objects that are partly obscured takes more brain power than anyone realised, say NASA researchers. The good news is that this may pave the way to better methods of training pilots and of helping air-traffic controllers spot planes. While the eyes of most animals track moving objects with jerky motions, primates use a continuous eye rotation called smooth pursuit. Neurologists assumed that a simple feedback loop from the retina to eye muscles could account for smooth pursuit by stopping the image of a moving object “slipping” on the retina. Most attempts to test this involved asking volunteers to track moving dots on a computer screen. But such experiments have missed the role of higher brain centres in smooth pursuit, according to Leland Stone, an engineer at NASA’s Ames Research Center in Moffett Field, California. “Real-world objects are not just spots,” he says. And people can easily track objects in complex settings, even with lots of other motion around. To test whether object recognition matters for smooth pursuit, Stone and his colleagues asked volunteers to watch a screen showing the outline of a diamond, most of which was obscured by thick vertical bars. As the diamond moved diagonally back and forth across the screen, only the vertical motion of the sides of the shape was visible through the bars (see Diagram). If smooth pursuit did involve a simple feedback loop between the retina and eye muscles, the volunteers’ eyes would only move vertically. In fact, they moved diagonally with the diamond, indicating that part of the brain had recognised the shape and estimated its trajectory, Stone says. The researchers then made the shape harder to recognise by eliminating the contrast between the vertical bars and the background, so that the diamond appeared as a few, skewed, lines. In this case, the volunteers’ eyes moved up and down, rather than diagonally, even though the motion on the screen was identical to that in the first test. Because the way our eyes move indicates whether or not we recognise a shape, understanding eye tracking could eventually help train pilots by revealing what they miss in a simulator. Sometimes pilots watching displays in simulators “crash” without knowing exactly why the problem occurred. “We may be able to tell how well pilots are perceiving what’s out there without interfering with what they are doing,” Stone says. And as displays in cockpits and control towers get more complex, eye tracking theory may someday reveal which presentations work well and which don’t. More on these topics: