Time...Is on My Side

Were I still a deadline-working fellow, I'd be waaay behind to pick up this April 2011 profile of David Eagleman, a neuroscientist at the Baylor College of Medicine. But since Eagleman's work focuses on how our brains perceive time, I think I could get myself off the hook.

You should read the whole thing, but there were some really neat pull-out nuggets in the story. One pointed out how our brains work to match up our sense of sight with our sense of smell. As you may remember from school, light travels much faster than does sound. This is why you may see lightning in a thunderstorm and not hear it until several seconds later.

But closer than a certain distance, we seem to see something and hear it happen more or less simultaneously. We might think that was because the distance was so small that even the slower sound waves traveled too fast to perceive the gap, but some of Eagleman's experiments showed that the human ear can distinguish gaps between sounds as small as five milliseconds. So even at short distances, the gap between sight and sound is enough that some people might notice it. Except, Eagleman found, the brain's audio processor works many times faster than its visual processor, meaning that even though the light gets a head start on its way from the eyes to the brain, the sound makes up for it by running a faster race. Only when the distance is great enough to overcome that speed difference do we start hearing things after we see them.

In fact, because our brains do take a definite time to process sensory inputs, we actually are a little bit behind the world around us. Not much -- we're still talking in fractions of a second here -- but a time discernible to sensitive instruments. So all of us, even the hippest hipster that ever hipped, are behind the times.

One other thing that caught my eye was an experiment in which a person was shown a series of pictures of the same object several times in a row, but every now and again a different picture was inserted into the series. Test subjects almost always said the picture of the different item was on the screen longer than the others, even though they were all on for the same amount of time. Eagleman says it may be because our brains develop a kind of short-hand processing for things that we're familiar with, and that means we don't pay attention to them for as long as we do to something new and different. There's a lesson in that somewhere. Probably a bunch of them.