Book review: the invisible gorilla

Authored by Christopher Chabris and Daniel Simon in 2010 (ISBN 978-0-307-45965-7).

SPOILER ALERT: before reading reading further, please count basketball passes.

According to these authors, approximately 50% of the people who view the video do not observe the gorilla. I read about the video before viewing it, so I have no first-hand knowledge. Both of my children did not not observe it. Of three adults I know who viewed the video, two observed the gorilla and one did not. How could it be that so many of us fail to observe what is right before our eyes? Natural selection, perhaps. There is great benefit to being able to focus on prey in the bush in front of you, or predators behind you, without considering an ongoing argument with a cave-mate.

You might say, after watching the video and reading my explanation, that the gorilla was black and half the players were black; there is no mystery in 50% of the subjects not observing it. Fair enough; the authors repeated the experiment with a red cross sign in place of the gorilla. This time the subjects did a little better, observing the cross 70% of the time. And, according to their studies, there is no such thing as an observant person, a person who consistently notices unexpected objects.

With this knowledge in hand, other strange conclusions emerge. Motorcyclists are at higher risk for accidents: they are less noticed and more vulnerable to injury. Should cyclists wear reflective clothing? The authors say it won't make much difference. The problem arises because motorists are not expecting motorcycles and thus do not observe them, even when seeing them, much like subjects plainly "see" the gorilla in the midst of the basketball players but do not observe it. Perhaps motorcycles should be outfitted with widely-spaced headlamps to mimic the front-ends of most automobiles. What about airplane pilots who collide with objects on the taxiway? Surely, a heads-up display would improve matters by allowing the pilots to look through their windshield all the time instead of shifting their gaze between the windshield and their instruments. Tests did not show any improvement, however. The authors interpret that result to mean that the problem was not that the pilots' eyes did not catch the light from the taxiway objects; rather, the pilots did not expect those objects to be there and so did not observe them. The problem is attention, not eyesight.

Given the foregoing I have decided to stop talking on a mobile phone while driving. Hands-free devices are not the answer either. The problem is attention, not finger coordination.

Related to the ability to observe the unexpected is the ability to observe unexpected changes. For instance, movies are not recorded end-to-end. Various scenes are recorded, out-of-order, and then re-ordered in the editing room. Thus, a sequence that takes place over one minute in the movie may have been recorded days apart. Staff on the set are responsible for ensuring that, for example, if the actor was wearing glasses on the first day of filming a scene then the actor must continue to wear glasses on the second day. Yet, mistakes are made, and a cottage industry has arisen, devoted to chronicling the mistakes movie directors and editors make when filming a movie.

This book is all about illusions. The first illusion, described above, is that we observe all there is to observe and that we can competently attend to more than one thing at a time.

The next illusion the authors consider is memory accuracy. The classic view is that memory is like a disk drive: observations come in, are written to disk, and are later retrieved. Sure, there are cases where our memory fails, but those are the exceptions, not the rule. It turns out that the disk drive metaphor is terribly wrong. Memories are profoundly influenced by emotions. Worse, our strength of recall is unrelated to accuracy. I remember this concept from my law school days: subjects were shown a video of a traffic accident and were later separated into two groups. The groups were asked similar, but different questions. For example, group one would be asked "did you observe a broken headlight" while group two would be asked "did you observe the broken headlight". The positive responses were higher for the first group. This result has been repeated countless times in sociology and psychology departments. And, these results are plainly visible in everyday life. The authors cite a study where subjects observed a staged crime and were later asked to identify the perpetrator. Some subjects were given longer, or less obscured views, than the other subjects; these subjects were better at identifying the staged criminal. Yet all subjects expressed the same confidence in their identification.

Shortly after 9/11 the younger President Bush was asked about his recollections of the attacks and his recollections did not match the agreed, actual sequence of events. Some viewed his statements as evidence of his prior knowledge. I was no fan of Bush but I do not think he would do such a thing, especially when faulty memory at a time of high emotionality explains the facts so well. As another example, Hillary Clinton the campaign trail proudly claimed to have touched down in Bosnia in the middle of a fire-fight; none of the press present that day recall such a thing. What would cause her to issue such a statement when it could so easily be proven wrong? Perhaps because she simply mis-remembered it.

Most of us also suffer from the illusion of knowledge. We think we know more than we do about just about everything we encounter. Consider the toilet: we all know how to operate one, but do we know how it works? Could we explain it to a five-year-old, to the repeated "why" questions he or she might ask? Could we draw a picture of a bicycle from memory? The authors cite examples from the investing world: hot-shots like Brian Hunter and hot-shot companies like Lehman Brothers. They certainly felt like they knew how the markets worked.

Another common illusion is using the particular to prove (or disprove) the general; related is the illusion of cause. Many among us believe that autism can be caused by vaccinations. These authors claim that is no proven correlation, let alone proven causation. Rather, the signs of autism manifest themselves around age 2, and most children receive a battery of immunizations at around the same time. This is unfortunate, because the diseases these vaccinations protect against, such as measles, are terrible diseases in their own right. One can only catch measles from someone else who has measles. Some children, such as those receiving certain organ transplants or cancer chemotherapy, should not receive the measles vaccination, and such children are at risk from those children who are not immunized but could be.

Again, the human tendency to conflate sequencing or correlation with cause is probably genetic. Survival is enhanced by the ability to form patterns from observations about the behaviors of predators and prey. I remember reading From Good to Great, where author Jim Collins cites the non-obvious behaviors of successful companies, and thinking that these behaviors were probably practiced by hundreds of failed companies, and further than many successful companies did not follow these practices. I think many recent business books are similar.

Did you know that playing Mozart for young children makes them smarter? It does not, or at least it has not been proven to do so by more than one research team. Media sources cited the original study, showing a relationship and helped generate millions of dollars of sales for Baby Einstein and similar products. Few people, and no one in mainstream media, paid any attention to subsequent studies that showed no relationship. The authors call this the illusion of potential: we can achieve more, if only we knew how. Did you know that we only use 10% of our brain power? I did not. I am not even sure what this means. What is your brain capacity? How is it measured? Why would we have all this unused capacity after millions of years of natural selection? Our big heads make childbirth more risky; wouldn't smaller, more efficient brains, provide a competitive advantage?

As other examples the authors cite studies regarding training your brain. It makes sense that exercising your brain will make it stronger, must like exercising your body. There is little evidence that this is true for adults (children being another matter entirely). Subjects who memorized long strings of numbers, for example, became good a memorizing long strings of numbers but no better at other cognitive tasks. In one study, though, aerobic exercise increased cognitive abilities (more so than stretching exercises). So, put away your Mozart CDs and your Sudoku puzzles and put on your sneakers.