Friday, July 25, 2008

Its all done with mirrors

Randall Parker blogs on illusions. Its appears that illusions are not merely central to understanding how perception works- perception is an illusion, since the brain is constantly struggling to anticipate the world, not merely to see it as it is.

In an experiment originated by Dr. Nijhawan, people watch an object pass a flashbulb. The timing is exact: the bulb flashes precisely as the object passes. But people perceive that the object has moved past the bulb before it flashes. Scientists argue that the brain has evolved to see a split second into the future when it perceives motion. Because it takes the brain at least a tenth of a second to model visual information, it is working with old information. By modeling the future during movement, it is “seeing” the present.

And we also fool ourselves, except when we are depressed:

Individual subjects were placed in front of a panel with a green light, a yellow light and a spring loaded button, and were instructed to make the green light flash as often as possible. In one segment, they would win money every time the green light went on. In another, they would lose money when it didn't. A screen in the room showed their score. Afterward, subjects were asked how much control they had. … Among the "normal," non-depressed subjects, it depended on whether they were losing or making money. When they were winning money, they thought they had considerable control. … When they were losing money, they thought they had virtually no control. In other words, these subjects took credit for good scores and dished off blame when scores were poor. … The depressed subjects saw things differently. Whether they were winning or losing money, they tended to believe they had no control. And they were correct: the "game" was a fiction.