Timewarp: How your brain creates the fourth dimension

... An intense experience, with heightened fear or excitement, rivets our attention and evokes the firing of many neurons across the brain, he says, causing us to soak up more sensory details (Philosophical Transactions of the Royal Society B, vol 364, p 1841). Richer memories seem to last longer, he says, because you assume you would have needed more time to record so many details. "Your brain is on fire when you're dropping," he says. "You lay down denser memory. When you read it back out, you think 'Gee, that was taking a long time'."

That could explain many other temporal illusions too, such as the "oddball effect". When people see the same thing over and over (a picture of a dog flashed on a computer screen, say) and then suddenly see something different (Margaret Thatcher), the new thing seems to last longer, even if all the pictures are actually shown for the same duration. Functional magnetic resonance imaging has revealed that the brain shows a spike in activity when confronted with a surprising stimulus, suggesting that it causes a richer memory to be laid down - which, according to Eagleman's theory, explains why the experience seems longer-lasting.

In total, Eagleman's theory seems to explain a dozen or so similar illusions.   ...

via Timewarp: How your brain creates the fourth dimension - life - 21 October 2009 - New Scientist.