Mind, consciousness and possibility

David Eagleman is a neuroscientist at Baylor College of Medicine who studies perception of time, circadian rhythms, time-traveling minds, and the essence of consciousness. Here’s the engrossing New Yorker report on his research.

Eagleman had to wait a few weeks to be granted an audience with Crick. (“I kind of became pals with his secretary,” he told me.) But they quickly hit it off and met regularly after that. Like Crick, Eagleman was fascinated by consciousness. He thought of time not just as a neuronal computation—a matter for biological clocks—but as a window on the movements of the mind. In a paper published in Science in 2000, for instance, Eagleman looked at an optical illusion known as the flash-lag effect. The illusion could take many forms, but in Eagleman’s version it consisted of a white dot flashing on a screen as a green circle passed over it. To determine where the dot hit the circle, Eagleman found, his subjects’ minds had to travel back and forth in time. They saw the dot flash, then watched the circle move and calculated its trajectory, then went back and placed the dot on the circle. It wasn’t a matter of prediction, he wrote, but of postdiction.

Something similar happens in language all the time, Dean Buonomano told me. If someone says, “The mouse on the desk is broken,” your mind calls forth a different image than if you hear, “The mouse on the desk is eating cheese.” Your brain registers the word “mouse,” waits for its context, and only then goes back to visualize it. But language leaves time for second thoughts. The flash-lag effect seems instantaneous. It’s as if the word “mouse” were changed to “track pad” before you even heard it.

Image: The Persistence of Memory

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  1. Pingback: Mind, consciousness and possibility revisited | The Human Fabric