The Runaway Species. David Eagleman

The consultants aren’t wrong, it’s simply that the details of their advice don’t matter. It’s not always about the particular solution, but instead about the variation.

      Why do humans adapt to everything around us so quickly? It’s because of a phenomenon known as repetition suppression. When your brain gets used to something, it displays less and less of a response each time it sees it. Imagine, for example, that you come across a new object – say, a self-driving car. The first time you see it, your brain shows a large response. It’s absorbing something new and registering it. The second time you see it, your brain shows slightly less response. It doesn’t care quite as much about it, because it’s not quite as novel. The third time: less response again. The fourth time: even less.

       Repetition suppression in action. ²

      

      The more familiar something is, the less neural energy we spend on it. This is why the first time you drive to your new place of work, it seems to take a long time. On the second day, the drive feels a little shorter. After a while, getting to work takes almost no time at all. The world wears off as it becomes familiar; the foreground becomes the background.

      Why are we like this? Because we’re creatures who live and die by the energy stores we’ve built up in our bodies. Navigating the world is a difficult job that requires moving around and using a lot of brainpower – an energy-expensive endeavor. When we make correct predictions, that saves energy. When you know that edible bugs can be found beneath certain types of rocks, it saves turning over all the rocks. The better we predict, the less energy it costs us. Repetition makes us more confident in our forecasts and more efficient in our actions.

      So there’s something appealing (and useful) about predictability. But if our brains are going to all this effort to make the world predictable, that begs the question: if we love predictability so much, why don’t we, for example, just replace our televisions with machines that emit a rhythmic beep twenty-four hours a day, predictably?

      The answer is that there’s a problem with a lack of surprise. The better we understand something, the less effort we put into thinking about it. Familiarity breeds indifference. Repetition suppression sets in and our attention wanes. This is why marriage needs to be constantly rekindled. This is why you’ll only laugh so many times at the same joke. This is why – no matter how much you enjoyed watching the World Series – you aren’t going to be satisfied watching that same game over and over. Although predictability is reassuring, the brain strives to incorporate new facts into its model of the world. It always seeks novelty. The brain gets excited when it updates.

      

      As a result of our neural machinery, good ideas don’t hold their shine. Take the list of the bestselling books from the year 1945:

      1. Forever Amber Kathleen Winsor

      2. The Robe Lloyd C. Douglas

      3. The Black Rose Thomas B. Costain

      4. The White Tower James Ramsey Ullman

      5. Cass Timberlane Sinclair Lewis

      6. A Lion Is in the Streets Adria Locke Langley

      7. So Well Remembered James Hilton

      8. Captain from Castile Samuel Shellabarger

      9. Earth and High Heaven Gwethalyn Graham

      10. Immortal Wife Irving Stone

      These were books that seized the public imagination, but it’s quite possible that you’ve never heard of any of them. Recall that these were the books on everyone’s lips that year. The authors honored dinners with their presence. They signed countless copies. Presumably, they would have had a hard time imagining these books would someday be totally forgotten.

      We constantly thirst for the new. In the movie Groundhog Day, a weatherman played by Bill Murray is forced to re-live a single day over and over again. Confronted with this seemingly endless loop, he eventually rebels against living through the same day the same way twice. He learns French, becomes a piano virtuoso, befriends his neighbors, champions the downtrodden.

      Why do we cheer him on? Because we don’t want perfect predictability, even if what’s on repeat is appealing. Surprise engages us. It allows us to escape autopilot. It keeps us awake to our experience. In fact, the neurotransmitter systems involved in reward are tied to the level of surprise: rewards delivered at regular, predictable times yield a lot less activity in the brain than the same rewards delivered at random, unpredictable times. Surprise gratifies.

      This is why jokes are structured the way they are. It’s never two guys who walk into a bar – it’s always three. Why? Because the first guy sets things up, and the second guy establishes the pattern. This is the shortest possible path for the third guy to break the pattern by sidestepping the brain’s prediction. In other words, humor arises from the violation of expectations. If you were to tell the joke to a robot it would simply listen to what each of the three guys does, but presumably it wouldn’t find the joke funny. The joke only works because the brain always tries to predict, and the punchline knocks it off balance.³

      Advertisers know that constant creativity is required to keep us engaged. Their ads nudge us towards a particular brand of detergent or chips or perfume but if the ads aren’t continually refreshed, we’ll tune them out; they lose their impact.

      The avoidance of repetition is the fountainhead of human culture. People often say that history repeats itself, but the statement is not quite true. At most, as Mark Twain said, history rhymes. It tries out similar things at different times, but the details are never the same. Everything evolves. Innovation is requisite. Humans require novelty.

      So there’s a balancing act here. On the one hand, brains try to save energy by predicting away the world; on the other hand, they seek the intoxication of surprise. We don’t want to live in an infinite loop, but we also don’t want to be surprised all the time. You don’t want to wake up tomorrow to find it’s Groundhog Day again, and you also don’t want to awaken to discover that gravity has reversed and you’re stuck against the ceiling. There’s a trade-off between exploiting what we know, and exploring the unknown.

      

      THE BALANCING ACT

      Brains seek a balance between exploiting previously-learned knowledge and exploring new possibilities. This is always a tricky trade-off.⁴ Say you’re deciding which restaurant to go to for lunch. Do you stick with your traditional favorite or try something new? If you go for your familiar haunt, you’re exploiting knowledge you’ve gained from past experience. If you jump into the culinary abyss, you’re exploring untried options.

      Across the animal kingdom, creatures set their trade-off point somewhere in the middle. If you learn through experience that the red rocks have grubs under them while the blue rocks do not, you need to exploit that knowledge. But one day you may find that grubs aren’t there, whether because of drought, fires or other foraging animals. The rules of the world rarely hold constant, and this is why animals need to take what they’ve learned (the red rocks yield grubs) and balance that against attempting new discoveries (I wonder what’s under these blue rocks?). And this is why an animal will spend most of its time looking under the red rocks, but not all of it. It’ll spend some time looking under the blue rocks, even if it has looked there several times in the past, unsuccessfully. It’ll continue to explore. It’ll also spend some time looking under the yellow rocks and in tree trunks and in the river, because one never knows where the next meal is going to come from. Across the animal kingdom, hard-won knowledge is counterbalanced with new pursuits.

      In the course of developing over eons, brains have achieved an exploration/exploitation trade-off that strikes the balance between flexibility and rigor. We want the world to be predictable, but not too predictable, which is why hairstyles don’t reach an endpoint, nor do bicycles, stadiums,