6. Be skeptical of your memories. In recent years, scientists have demonstrated that human memories are surprisingly dishonest. The act of recalling an event (say, your eighth birthday party) changes the structure of that memory in the brain. Details are tweaked; the narrative is altered. The more you think about it, the less accurate your recollection becomes, and the less reliable it is as a basis for making any kind of conclusion. (So maybe you shouldn’t hire a clown for your kid’s party after all.)
 
 7. Don’t expect to diet and finish the crossword. It turns out that the prefrontal cortex, the area of the brain responsible for willpower and cognitive thought, is a rather feeble bit of flesh and easily depleted. In a telling study, people who were asked to remember a seven-digit number and then offered a snack were much more likely to choose chocolate cake over fruit salad than were those who were asked to remember a one-digit number. The first group’s self-control “muscles” were exhausted! It’s important to realize that you can do everything―just not all at once.
 
 8. Study your mistakes. One common trait of successful people is their willingness to focus on their fumbles. Even when they do well, they insist on looking at what they could have done better. Such perfectionism might not be a recipe for happiness, but it’s a vital component of learning, since brain cells figure out how to get things right by analyzing what they got wrong.
 
 9. Go ahead and daydream. Forget efficiency. Scientists have discovered that daydreaming is an important tool for creativity: It causes a rush of activity in a circuit known as the default network, which connects different parts of the brain and allows the mind to make new associations. The daydreaming brain is actually in overdrive.
 
 10. Think about thinking. Metacognition, as this is known, is a crucial skill. Many scientists argue that the best predictor of good judgment isn’t intelligence or experience; it’s the willingness to engage in introspection. The brain is like a Swiss Army Knife, full of different tools. When picking out a couch, we can trust our emotions, but we should rely on the rational brain when scrutinizing the fine print of a mortgage. Unless you think about which mental tool is best suited for the task at hand, you could end up flustered, even sweating, in the sofa aisle at Ikea.
 
 About the Author
Jonah Lehrer worked for several years in a neuroscience lab before becoming a science writer. His second book, How We Decide (Houghton Mifflin Co., $25, amazon.com), was published recently. He lives in Boston with his wife.