We tend to gather research that confirms our own biases — a phenomenon called, not surprisingly, confirmation bias by social scientists.

A blatant but true example from the Heaths’ book is that back in the 1960s, before we had so much medical information on the dangers of smoking, smokers were much more likely to read an article headlined, “Smoking Does Not Lead to Lung Cancer,” than one with the headline, “Smoking Leads to Lung Cancer.”

We let emotions play too big a role. They can be set off by situations unrelated to the event. If you’re going on a first date, for example, Professor Gino said, and get caught in traffic, you may feel angry and that can spill over into your date. You may decide it was just a bad match, rather than reflecting on the mood you were in when you arrived.

Most of us tend to be overly optimistic about the future and about own abilities and attributes. The Heaths cite studies showing that doctors who reckoned they were “completely certain” about a diagnosis were wrong 40 percent of the time.

I liked even more a 1997 survey conducted by U.S. News & World Report of 1,000 people, cited by Professor Gino, about who was most likely to get into heaven. Michael Jordan had a 65 percent chance, Mother Teresa a 79 percent chance. But 87 percent of the survey takers decided they were the ones most likely to go to heaven.

So we’re overconfident, emotional and irrational. What do we do about it?

Being aware when we make decisions that our own feelings, our relationships to others and outside powers all have an impact is a good start, Professor Gino said.

Here’s one of her suggestions: Take your emotional temperature. Try to be more aware of where your emotions are coming from and how, even if seemingly irrelevant, they may be clouding your decision.