The Power of Habit: Why We Do What We Do in Life and Business Read Online Free PDF Page A

routines. In surgery, each rat had what looked like a small joystick and dozens of tiny wires inserted into its skull. Afterward, the animal was placed into a T-shaped maze with chocolate at one end.

    The maze was structured so that each rat was positioned behind a partition that opened when a loud click sounded. 1.16 Initially, when a rat heard the click and saw the partition disappear, it would usually wander up and down the center aisle, sniffing in corners and scratching at walls. It appeared to smell the chocolate, but couldn’t figure out how to find it. When it reached the top of the T, it often turned to the right, away from the chocolate, and then wandered left, sometimes pausing for no obvious reason. Eventually, most animals discovered the reward. But there was no discernible patternin their meanderings. It seemed as if each rat was taking a leisurely, unthinking stroll.

    The probes in the rats’ heads, however, told a different story. While each animal wandered through the maze, its brain—and in particular, its basal ganglia—worked furiously. Each time a rat sniffed the air or scratched a wall, its brain exploded with activity, as if analyzing each new scent, sight, and sound. The rat was processing information the entire time it meandered.

    The scientists repeated their experiment, again and again, watching how each rat’s brain activity changed as it moved through the same route hundreds of times. A series of shifts slowly emerged. The rats stopped sniffing corners and making wrong turns. Instead, they zipped through the maze faster and faster. And within their brains, something unexpected occurred: As each rat learned how to navigate the maze, its mental activity
decreased
. As the route became more and more automatic, each rat started thinking less and less.

    It was as if the first few times a rat explored the maze, its brain had to work at full power to make sense of all the new information. But after a few days of running the same route, the rat didn’t need to scratch the walls or smell the air anymore, and so the brain activity associated with scratching and smelling ceased. It didn’t need to choose which direction to turn, and so decision-making centers of the brain went quiet. All it had to do was recall the quickest path to the chocolate. Within a week, even the brain structures related to memory had quieted. The rat had internalized how to sprint through the maze to such a degree that it hardly needed to think at all.

    But that internalization—run straight, hang a left, eat the chocolate—relied upon the basal ganglia, the brain probes indicated. This tiny, ancient neurological structure seemed to take over as the rat ran faster and faster and its brain worked less and less. The basal ganglia was central to recalling patterns and acting on them. The basal ganglia, in other words, stored habits even while the rest of the brain went to sleep.

    To see this capacity in action, consider this graph, which shows activity within a rat’s skull as it encounters the maze for the first time. 1.17 Initially, the brain is working hard the entire time:

    After a week, once the route is familiar and the scurrying has become a habit, the rat’s brain settles down as it runs through the maze:

    This process—in which the brain converts a sequence of actions into an automatic routine—is known as “chunking,” and it’s at theroot of how habits form. 1.18 There are dozens—if not hundreds—of behavioral chunks that we rely on every day. Some are simple: You automatically put toothpaste on your toothbrush before sticking it in your mouth. Some, such as getting dressed or making the kids’ lunch, are a little more complex.

    Others are so complicated that it’s remarkable a small bit of tissue that evolved millions of years ago can turn them into habits at all. Take the act of backing your car out of the driveway. When you first learned to drive, the driveway required a major dose of