The Power of Habit: Why We Do What We Do in Life and Business

by Charles Duhigg

Habits, scientists say, emerge because the brain is constantly looking for ways to save effort.

A lot of people have highlighted this sentence, which I think is really cool, because it reflects a basic insight that has become fundamental to cognitive sciences: Many of our brain’s quirks occur because, at root, we want to conserve energy. Brains (and neurological structures) that can operate without requiring huge effort have a huge evolutionary advantage. Much of what we’re leaning from behavioral economics - such as why people tend to react in (seemingly) irrational ways - are reflections of this basic principle: The best brains are efficient. They try to automate basic decision making, so we can save cognitive energy for other, more important tasks. And that causes some glitches sometimes. (For instance, we stamp on the brakes when we see a cop car out of the corner of our eyes, or unthinkingly take the exit to go home when we’re intended to drive to the movies.) But those glitches are small prices to pay for having brains that can continuously - and nearly automatically - get more and more efficient at doing hard things.