Seduced by Numbers

Recently I was riding in the car with a good friend Amy and her little boy Adam who had just learned his numbers. He kept his eye on the speedometer of Amy's car and called out every time his mother went over or under the speed limit. Amy is a very good and safe driver, and she obeyed traffic rules, but, at times, she had to accelerate or decelerate to match her car's speed to the traffic around her. Her little boy, however, with his new command of numbers, knew only one way to judge her driving.

We all do this. We are seduced by numbers. Sometimes if we hear the same statistic repeated over and over again, we believe it, even if it makes no sense. Consider the oft repeated phrase, "We use only 10% of our brain." Where did this idea come from? It doesn't hold up to scientific observations. When scientists use brain imaging techniques to monitor the activity of the human brain, they find that large areas of the brain are active even when we are at rest or asleep.

Numbers, especially test results, tell us how we do on specific exams or tasks, but they don't tell us how we function in real life. Unfortunately, in science, medicine, and education, numbers are all too often given too much weight.

When I was growing up, I had 20/20 acuity in both eyes but did poorly in school. With my 20/20 results on the school vision screening, everyone assumed I had perfect vision. But, I was cross-eyed so my eyes didn't point to the same place in space. When we read, it's best if we aim both eyes at the same letter on the page at the same time. However, my left eye looked to the right of where my right eye was looking. The letters on the page seemed to me to shift and change places. This problem was not picked up by the school vision screening which examined how each eye saw separately but not how well the two eyes worked together. So, my principal was convinced that my vision had nothing to do with my reading problems and my low scores on standardized tests. The numbers didn't lie. My reading problems were blamed on low intelligence.

When my husband Dan was a young rehabilitation doctor, he was asked to examine an elderly man who had suffered from polio as a child. Dan walked into the examining room and then tested the strength of this man's walking muscles. He graded them as very weak. After the exam, a senior physician asked my husband a simple question: Could the patient walk? Dan had not tested this, but he assumed, from the numbers on his exam, that this was not possible. So the senior physician and my husband returned to the examining room and asked the man to walk. The gentleman got up from the examining table with no apparent concern and walked across the room. It was only later that my husband realized that the senior physician had set things up to make a point. The patient indeed had very weak walking muscles, but he had developed his own way of walking using his surviving muscles. The results of my husband's exam did not address how well this patient could manage in real life. Yet, it was his day-to-day functioning that mattered.

Life is very complicated and it's nice to have numbers, objective and discrete, to help make sense of the world. However, we should not let the numbers from test results seduce us into a false sense of confidence. We must continually question our assumptions and ask whether the statistics we generate from tests and experiments accurately reflect the way we actually do things in real life. Even for everyday acts such as looking, reading, and walking, our performance should never be reduced to a mere set of numbers.