The Invisible Gorilla: How Our Intuitions Deceive Us by Christopher Chabris and Daniel Simons – New York: Crown Publishing Group, a division of Random House, 2009

Where is the invisible gorilla? Right before your eyes. This is a U-tube version of the famous Selective Attention Test that has been viewed by millions and is described in detail in the Chabris & Simons book.

This is just one example that illustrates how our brains can deceive us by taking efficiency “short-cuts”. In the gorilla experiment, our attention is focused on a specific task and this is a good thing. It allows us to accurately count the number of times a basketball is passed between players wearing a white top. The bad thing is that this keen focus on the task at hand blinds us to the gorilla walking between the players. The gorilla is unexpected and we are effectively blind to its presence. This book is a fascinating read providing insight into how our brains actually work away in the background, filtering the massive input of the world into a digestible amount of information. In most cases, we see what we expect to see and are convinced that what we are aware of is all that there is to see. This is a dangerous assumption.

The general public will enjoy this book as it provides an interesting guide to the everyday illusions that may cause us to act against our own best interests. This guide to the brain will help you avoid, or at least recognize the problems. If you have extensive interaction with the health care world, this book is another very helpful resource. Chabris & Simons’ experiments directly address how we all evaluate experts and the results are surprising. More than this, I found the concept of “change blindness” fascinating. It is related to the type of inattentional blindness that allows us to miss the gorilla on the basketball court, but it is different. With “change blindness – people are “blind” to the changes between what was in view moments before and what is in view now…. Change blindness occurs when we fail to compare what’s there now with what was there before”. The various psychological experiments described in the book are necessarily limited to short term investigations, but this concept reminded me of the stories in Jerome Groopman’s book, “How Doctors Think”. He relates stories where physicians have clung to an old diagnosis and ignored progression of and changes in the patient’s signs and symptoms. The diagnosis was made and then never challenged.

Children with early onset neurological problems are particularly vulnerable to this problem. In the early days, they have evidence of a damaged brain or peripheral nerve injury, but there is nearly always some improvement. They are born with an immature brain, but that brain will grow and mature over time. The early diagnosis may still be present, but new skills and abilities may be overlooked. One such case is discussed in my post, “What is the Diagnosis?’ If a young woman can accurately hit a series of high speed volleys in tennis, this skill is inconsistent with her diagnosis of choreoathetosis. Parents of children with cerebral palsy or brachial plexus injury need to repeatedly bring their child’s new accomplishments to the attention of their health care team. One example in my career was a newborn with an odd metabolic anomaly. The exact diagnosis was not then possible, but the parents were told that the problem had an extremely poor prognosis. This prognosis stayed on the child’s chart, in spite of his near normal development. Parents need to keep their child’s medical record current to their present condition. The danger is that busy physicians and therapists may not recognize the higher order skills and not demand the best possible output from the child. They have to know the child’s best skill level so that they can work to improve the consistency of the child’s performance.



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