Why Behavior Overshadows Statistics

A more homely example is provided by a recent news story in Philadelphia about a 911 operator who allegedly diverted business to a private ambulance service. The possible delay in rerouting that was involved may have contributed to the caller’s death, and the story was front-page news for several days.

As I mentioned in a column last year, what hasn’t been front-page news is an unrelated, but much more important ambulance story: The fact that automatic external defribillators are deployed in only half of all ambulances and fewer than 1 percent of emergency police and fire vehicles. The Red Cross and emergency personnel estimate that the broad deployment of these inexpensive portable devices could save thousands of lives in the United States annually.

A Puzzle In our reaction to these and countless other stories we are probably responding in very natural ways. Probability and risk assessment don’t register easily with people, whereas misbehavior does. There’s even a classic psychological experiment that underscores our sensitivity to law-breaking.

The psychologist Peter Wason demonstrated that most subjects are not very good at the following task: Four cards, each with a number on one side and a letter on the other, are displayed on a table. The subject is asked which cards he must turn over to confirm the statement: If a card has a D on one side, it has a 3 on the other. The four cards before him have, respectively, a D, F, 3, and 2 facing up. Wason found most people incorrectly turn over the D and 3 cards instead of the D and 2. (If the 2 has a D on the other side, it disproves the statement. A 3 with a different letter on the other side does not.)

Contrast this task with another one involving a possible social infraction. A bouncer at a bar must throw out underage drinkers. He’s confronted with four people: a beer drinker, a cola drinker, a 28-year-old, and a 16-year-old. Which two should he interrogate further? Here it’s clear to almost everyone that it’s the beer-drinker and the 16-year-old who must be interrogated.

But this problem is logically equivalent to the first one! (What a person is drinking is “one side” of him, his age is the other, and the bouncer must confirm the statement: If a person is drinking alcohol, then he is over 18.)

For better or worse, we often seem to be more responsive to particular wrongdoings than to the general well-being.

Professor of mathematics at Temple University, John Allen Paulos is the author of several best-selling books, including Innumeracy and A Mathematician Reads the Newspaper. His Who’s Counting? column on ABCNEWS.com appears on the first day of every month.

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