Truth 16. You may see only what you're looking for

In his examination of how physicians think, physician and author Jerome Groopman notes that most physicians come up with two or three possible diagnoses within minutes of meeting a patient.⁹ These decisions are influenced by the patients who came before, something known as an availability bias. We tend to try to fit the current situation to other examples readily available from our own experience.

For example, Groopman tells the story of a doctor on a Navajo reservation in Arizona who had seen dozens of patients over a three-week period suffering from viral pneumonia. So when a woman in her sixties complained that she was having trouble breathing, he determined that she had subclinical pneumonia. He made the diagnosis even though some of her symptoms and test results didn't fit this diagnosis (no signs of pneumonia on X-rays or elevated white blood counts). He ignored the facts.

We tend to try to fit the current situation to other examples readily available from our own experience.

It was only after an internist looked at the results that he pointed out that the woman was actually suffering from aspirin toxicity. All the symptoms fit this diagnoses, and when the internist pointed that out, the doctor saw it instantly. But because of the other cases of pneumonia around him, he had missed it. This was a case where an experienced physician, relying on intuition or what he believed was a careful analysis of the situation, could be led astray by the cases that came first. He saw what he was prepared to see.

Some riddles are based on the same notion. (If red houses are made of red bricks, yellow houses are made of yellow bricks, and blue houses are made of blue bricks, what are greenhouses made of? While "green bricks" comes to mind, the answer, of course, is glass.) If you're launching a new business and three friends have just had to shut down their operations, you might overestimate the risks. On the other hand, if the three friends have achieved smashing successes, you might underestimate the risks. Neither view is the right one.

When you're making a decision, think about how your past decisions, your educational background, and your experience predispose you to look at the decision in a certain way. What could you see if you came to the decision fresh? What different decisions could this allow you to make?