in the world because our brains are pretty good at automatic triage.
“Most of the time your brain can filter things out,” said Strayer,
driving the black 4Runner over an increasingly rough dirt road. “It’s a
strategic process. If traffic is heavy, your brain literally stops
listening to NPR. Radio is a passive signal, but talking is a whole
different thing, and if you’re on the phone talking to your spouse,
that’s more difficult to shut out.” Hence your inability to respond as
quickly as you should to traffic signals, signs and pedestrians. Social
information, as all Tweeters, texters and emailers know, draws our
attention and is tough to shut out. I was reminded of a funny
automated email response sent by a scientist on vacation (which I
learned about through, of course, Twitter): “I am away from the office
and checking email intermittently. If your email is not urgent, I’ll
probably still reply. I have a problem.”
“Attention is everything,” explained Paul Atchley, pivoting
around in the front seat. “Without it, we don’t see, hear, taste. Your
brain keeps track of about four things at once. How do you prioritize
what’s important and what’s not? Through inhibition. I’ve always
found it interesting that most connections in the brain are inhibitory
functions. We have far more information than we can deal with. Most
of what the brain is doing is filtering, tuning stuff out so we can focus
in on things that are relevant.”
Because of this interplay of observation, selective attention and
inhibition, humans are able to achieve higher-order cognition, which
includes creative problem-solving, goal-following, planning and
multitasking. The problem is that all this inhibition and filtering uses
up cognitive fuel. It wallops us. As Stanford neuroscientist Daniel
Levitin points out in The Organized Mind, our brain’s processing
speed is surprisingly slow, about 120 bits per second. For perspective,
it takes 60 bits per second just to understand one person speaking to
us. Directed attention, or voluntary attention, is a limited resource.
When it flags, we make mistakes; we get irritable. Moreover, task-