David Eagleman is a neuroscientist at Stanford, author and the writer & presenter of the PBS series The Brain. He studies time perception, sensory substitution, synesthesia, and neurolaw, and has 3 startups that have spun out of his laboratory. Eagleman is a Long Now board member.

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David Eagleman gives the keynote talk on "The Brain and The Now" at the Long Now Member Summit and is joined onstage after his talk by Stewart Brand and Danny Hillis for further discussion and Q&A.

02016 marks The Long Now Foundation's 20th year and we are holding our first Summit to showcase and connect with our amazing community, on Tuesday October 4, 02016 from noon to 11:30pm, at Fort Mason Center in San Francisco.

The Brain’s Now

Our perception of time raises all sorts of questions, Eagleman began. “Why does time seem to slow down when you’re scared? And why does it seem to speed up as you get older?”

With an onscreen demonstration, Eagleman showed that “Time is actively constructed by the brain.“ His research has shown that there’s at least a 1/10-of-a-second lag between physical time and our subjective time, and the brain doesn’t guess ahead, it fills in behind. “Our perception of an event depends on what happens next.” In whole-body terms, we live a half-second in the past, which means that something which kills you quickly (like a sniper bullet to the head), you’ll never notice.

In order to manage a realistic sense of causality, the brain has to calibrate the rate of different signals coming into it. When that system malfunctions, you can get “credit misattribution”—the sense that “I didn’t do that!” It may explain why some schizophrenics think that their normal internal conversation is voices coming from somewhere else, and it might be curable by training their brain to manage signal lags better.

Is “now” expandable? Why do you seem to experience time in slow motion in a sudden emergency, like an accident? Eagleman’s (terrifying) experiments show that in fact you don’t perceive more densely, the amygdala cuts in and records the experience more densely, so when the brain looks back at that dense record, it thinks that time must have subjectively slowed down, but it didn’t. “Time and memory are inseparable.”

This also explains why time seems to speed up as you age. A child experiences endless novelty, and each summer feels like it lasted forever. But you learn to automatize everything as you age, and novelty is reduced accordingly, apparently speeding time up. All you have to do to feel like you‘re living longer, with a life as rich as a child’s, is to never stop introducing novelty in your life.