The Availability Heuristic

[Bayes]

Another great article from youarenotsosmart.com.

The Misconception: With the advent of mass media, you understand how the world works based on statistics and facts culled from many examples.

The Truth: You are far more likely to believe something is commonplace if you can find just one example of it, and you are far less likely to believe in something youââ,¬â,,¢ve never seen or heard of.

Do more words begin with ââ,¬Å"rââ,¬Â or have ââ,¬Å"rââ,¬Â as the third letter?

Think about it for a second.

If you are like most people, you think there are more which begin with ââ,¬Å"rââ,¬Â ââ,¬â€œ but youââ,¬â,,¢re wrong.

Itââ,¬â,,¢s much easier to believe the first option because it takes more concentration to think of words with ââ,¬Å"rââ,¬Â in the third position.

Try it.

If someone you know gets sick from taking getting a flu shot, you will be less likely to get one even if it is statistically safe. In fact, if you see a story on the news about someone dying from the flu shot, that one isolated case could be enough to keep you away from the vaccine forever.

On the other hand, if you hear a news story about how eating sausage leads to anal cancer, you will be skeptical, because it has never happened to anyone you know, and sausage, after all, is delicious.

Or, if you hear about a rash of school shootings around the country, you will support the installation of metal detectors in your county despite the statistical odds of a school shooting where you live being extremely low.

You are just not so smart when it comes to the availability heuristic.

The human mind is generated by a brain which was formed under far different circumstances than the modern world offers up on a daily basis. Over the last few million years, much of our time was spent with less than 150 people, and what you knew about the world was based on examples from your daily life.

Mass media, statistical data, scientific findings ââ,¬â€œ these things are not digested as easily as something youââ,¬â,,¢ve seen with your own eyes. The old adage, ââ,¬Å"Iââ,¬â,,¢ll believe it when I see it,ââ,¬Â is the availability heuristic at work.

Politicians use this all the time. Whenever you hear a story which begins with, ââ,¬Å"I met a mother of two in Michigan who lost her job because of a lack of funding forââ,¬Â¦Ã¢â,¬Â or something similar, the politician hopes the anecdote will sway your opinion. They are betting the availability heuristic will influence you to assume their one example was indicative of a much larger group of people.

Itââ,¬â,,¢s simply easier to believe something if you are presented with examples.

School shootings were considered to be a dangerous new phenomenon after Columbine. That event fundamentally changed the way kids are treated in American schools, and hundreds of books, seminars and films have been produced in an attempt to understand the sudden epidemic.

The truth, however, was there hadnââ,¬â,,¢t been an increase of school shootings. During the time when Columbine and other school shootings got major media attention, violence in schools was down over 30 percent. Kids were more likely to get shot in school before Columbine, but the media during that time hadnââ,¬â,,¢t given you many examples.

A typical school kid is three times more likely to get hit by lightning than be shot by a classmate, yet schools continue to guard against it as if it could happen at any second.

When you buy a lottery ticket, you imagine yourself winning like those people on television who get suddenly famous when their numbers are chosen, but you are far more likely to die in a car crash on the way to buy the ticket than you are to win.

You donââ,¬â,,¢t think in statistics, you think in examples, in stories. When it comes to buying lottery tickets, fearing the West Nile virus, looking for child molesters, and so on, you are not so smart.

[TwoCatSam]

Bayes

Thanks for another thought-provoking article.

Sam

[Bayes]

Hi Sam,

It's Thomas Bayes, one of the "fathers" of probability theory.

[TwoCatSam]

Bayes

Just as I typed that, the phone rang.  I then Googled and learned the answer.  Thus my edit.

I should Google first, ask second.

Thanks

Sam