Burkhard Bilger’s article on David Eagleman in the April 25 New Yorker is one of the most interesting things I’ve read in a long time; I haven’t even finished it yet, but I had to post a passage from page 59 that provides a nice use of the word postdiction (see this LH post from a year ago) and a linguistic example. Eagleman studies our sense of time and how the brain creates it:
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.
The article is wonderfully written (“The most recent neuroscience papers make the brain sound like a Victorian attic, full of odd, vaguely labelled objects ticking away in every corner”), and you won’t regret devoting a chunk of your day to reading it.