Predictably Irrational is one of several popular books about the way people really make decisions and judgments. This growing sub-genre includes Nudge, Sway and Mistakes Were Made (But Not by Me).

Ariely lucidly explains the findings of various experiments about decision making. It's easy to find applications in marketing: offering options that serve as anchor points and recognizing the power of "free." These findings are useful but I would like to see more discussion of the implications for everyday life.

For example, most of us cannot predict how we will behave when we're swept up by strong emotions. Yet every day judgments are made by jurors in courtrooms based on, "Well, if I were in that situation..."

Ariely points out the futility of taking too long to make certain decisions. One friend kept dithering over the choice of a digital camera, only to forego months of memories captured on film.

Similarly, he feels he took too long to evaluate a job offer from Stanford. But for major life decisions, a lengthy process can be rational, even if you sacrifice current productivity. You have a greater likelihood of identifying the fact or factor that will be the ultimate deal-breaker.

Ariely created an experiment to demonstrate that keeping options open comes with a high cost. So, he says, keeping one job or one residence for a long time can have a high payoff. Maybe. But often outsourcing options or industry shifts will kill a career. As a career consultant, I advise clients to focus on marketability, not security.

Second, Ariely shows that money changes relationship dynamics. As he says, your family would be insulted if you offered to pay for Thanksgiving dinner.

But while he advocates a greater role for social norms (p. 88), money norms often smooth difficult transactions. The New York Times magazine recently featured an article by an unmarried professional woman who needed a kidney. She wished she could just pay for what she wanted instead of being forced into difficult conversations that threatened her friendships.

Many of us who move frequently have learned to pay packers and movers rather than seek help from well-meaning friends. After all, your helper might drop your new high-definition TV on the sidewalk (maybe breaking a toe in the process).

The absence of money also affects relationships. When strangers email to ask how to resolve a challenging career question or fix a troubled website, I often wonder what goes through their minds. When friends ask, they risk the friendship.

Third, Ariely suggests (p 121) that we apply lessons from auto maintenance to motivate individuals to undergo medical exams. This reasoning seems flawed.

Tests won't prolong lives the way regular oil changes prolong the lives of car engines. After a diagnosis of disease, you should consider false positives. You embark on a journey of life-changing (and life-threatening) medical procedures, lifestyle changes, battles with insurance companies and endless waits to deal with rushed, indifferent or even rude medical staff. A better analogy would be to compare medical exams to auto diagnostics (which car owners rarely choose) or else compare teeth cleaning to oil changes.

Insurance creates economic disincentives that muddy the waters. I know several people who had tests that came back negative -- no disease. A few months later, these folks developed symptoms that suggested a need to repeat the tests. In every case, the insurance company said, "No -- you get one a year." One person told me her doctor ruled out her disease based on a test she'd taken a few months earlier. So skipping a routine exam can be rational.

Any benefits of early detection accrue to the individual, not society or insurance companies. Those who stay alive while making ongoing demands on the medical system will cost more than those who are rushed to the hospital in crisis and die shortly afterward.

In any case, Ariely discusses how doctors resist research findings that point to the effectiveness of placebos. Just what is rational thinking, anyway?

Overall, though, I thoroughly enjoyed this book. Ariely's writing entertains as well as informs. We all need to base our decisions and our lives on how human minds really work, not what "everybody" knows.

This was an excellent read. It was entertaining and moved very fast. He provided a lot of information about how we thought and the ways we thought. If you are even remotely interested in how the human mind works, this is an excellent read. We are not the rational animals that we think we are and this book points out all of our lovable quirks.