The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us (29 page)

Adrian Sandler and his colleagues conducted one of these clinical trials. They randomly assigned 28 children to receive a dose of secretin and another 28 to receive a placebo. Not surprisingly (at least in hindsight), they found no benefit whatsoever from the secretin. The more interesting finding of this study came from interviews conducted afterward with the parents of the children: Even after learning that secretin had no benefit at all, 69 percent of them remained interested in injecting their child with it. In another double-blind study, parents were asked to guess whether their child had received secretin or the placebo. Parents often believe that they can detect effects that are missed by the more objective measures used in studies, and they use that belief to justify their continued faith in the efficacy of the treatment. In this case, though, the parents could not even guess successfully whether or not their child had received secretin—they had no idea whether their child had received the drug precisely because the drug had no detectable effect.

A central problem in combating medical anecdotes with hard data is that in any clinical trial, some people receiving the treatment will improve and some won’t. Our tendency is to remember the cases where people improved and to assume that the treatment caused the improvement. What we usually fail to do is to compare the rates of improvement with the treatment and without the treatment. If the treatment has a causal effect, then a greater proportion of those who received the treatment should improve than those who didn’t. If the treatment doesn’t have a causal effect, then other, uncontrolled factors probably led some people to improve anyhow.

Just as business authors rarely consider how many companies follow the ideas they champion but still fail, or how many companies succeed with other approaches, people thinking about stories of vaccination and autism do not tally up the number of children who receive vaccines and do not develop autism, who show symptoms before vaccination, or who show symptoms without having been vaccinated. When these numbers
are
properly taken into account, it becomes clear that children tend to
be diagnosed with autism at the same rates and at the same ages regardless of whether or not they received vaccinations.
³⁴
The problem is exacerbated by the typical developmental trajectory of cognition and behavior. As any parent knows, development is not a continuous, gradual process. Just as children grow physically in spurts, they develop cognitively in spurts as well. Children with autism are much the same. For long stretches, they might show no improvement, only to show a big change in a short time frame. If parents happen to notice improvement while they are trying some new miracle cure, they will readily associate the treatment with the improvement.
³⁵

Accepting that a perceived cause is illusory can be difficult, and overcoming anecdotes with science and statistics can be even harder. Perhaps the best indication of the powerful hold of these anecdotal hypotheses comes from the emotions they inspire. Offit’s authoritative book on the lack of scientific links between autism and vaccination has an average customer rating of 3.9 on the 1–5 scale at Amazon.com. However, in this case, the average is not typical of the individual reviews. Of the 102 reviewers at the time of this writing, not a single one gives the book the middle rating (three stars), whereas 70 give it the highest possible rating and 25 give it the lowest possible rating!
³⁶

Despite the now-overwhelming evidence that vaccinations are not at all associated with autism, 29 percent of people in our national survey agreed with the statement “vaccines given to children are partly responsible for causing autism.”
³⁷
It’s a bit reassuring that all the media attention to this illusory cause hasn’t influenced more people, but science can only claim a partial victory at best. If 29 percent of parents follow through on such beliefs and do not vaccinate their children, population immunity could drop precipitously, leading to widespread measles outbreaks. Moreover, new autism “cures” relying on anecdotal evidence rather than careful experimentation continue to surface and lead parents down dangerous paths. We hope that reading this chapter has given you some immunity to these attempts to exploit the illusion of cause.

We have explored three ways the illusion of cause can affect us. First,
we perceive patterns in randomness, and we interpret these repeating patterns as predictions of future events. Second, we look at events that happen together as having a causal relationship. Finally, we tend to interpret events that happened earlier as the causes of events that happened or appeared to happen later. The illusion of cause has deep roots. We humans are distinct from other primates in our ability to perform “causal inference.” Even young children realize that when one object hits another, it can make the other object move. They can reason about hypothetical causes as well: If an object moved, something must have caused it to move. Our primate relatives generally do not make these inferences, and consequently, they have trouble learning about causes that they can’t see.
³⁸
On the timeline of evolution, therefore, the ability to infer the existence of hidden causes is quite recent, and new mechanisms often need refinement. We have no trouble inferring causes—the real trouble is that we are sometimes too good at inferring causes for our own good.

B
EFORE THE 2007 NATIONAL FOOTBALL
League season, as before every season, the New York Jets made several adjustments to the team. Rookies arrived at training camp, some veterans left the team, other players had to compete for positions on the starting roster, and the playbook was updated. But one change was more unusual: Head Coach Eric Mangini ordered that the stadium loudspeakers play classical music—specifically, compositions by Wolfgang Amadeus Mozart—during team practices. “Mozart’s music and brain waves are very similar, and it stimulates learning,” explained Mangini, a coach known for meticulously preparing his team.
¹

Eric Mangini has much company in believing that listening to Mozart can make you smarter. An entrepreneur named Don Campbell trademarked the phrase “The Mozart Effect” and used it to market a series of books and CDs for adults and children alike. Campbell even consults with hospitals on the optimal design of sound systems to maximize the healing powers of music.
²
In 1998, Governor Zell Miller persuaded the Georgia legislature to spend public money to issue classical music tapes to all parents of newborn babies in the state. As part of his state-of-the-state speech, he played Beethoven’s “Ode to Joy” to
the legislators and asked, “Don’t you feel smarter already?”
³
A hospital in Slovakia puts headphones on all of the infants in its nursery, within hours of their birth, to give them a true head start on building their brainpower. “Mozart’s music has a very good effect on the development of the intelligence quotient,” said the doctor who started the practice there.
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So far, we have discussed several everyday illusions that expose errors in the way people think about their own minds, and we have tried to convince you that these errors can have dramatic consequences for human affairs. We have also suggested ways to minimize the impact these illusions have on your own life. With our understanding of these illusions, we have found it possible—though far from easy—to change our mindset so as to recognize and escape them at least some of the time. But we would all be better off if there were a simple way to overcome everyday illusions, a way to increase our brainpower enough to make the illusions just disappear.

The
illusion of potential
leads us to think that vast reservoirs of untapped mental ability exist in our brains, just waiting to be accessed—if only we knew how. The illusion combines two beliefs: first, that beneath the surface, the human mind and brain harbor the potential to perform at much higher levels, in a wide range of situations and contexts, than they typically do; and second, that this potential can be released with simple techniques that are easily and rapidly implemented. The story of the Mozart effect is a perfect illustration of how this illusion can transform a claim with almost no scientific support into a popular legend that fuels multimillion-dollar businesses, so we will begin this chapter by going into it in depth.

The Mozart effect burst into public consciousness in October 1993 when
Nature
, one of the top two scientific journals (the other being
Science)
, published a one-page article by Frances Rauscher, Gordon Shaw, and Katherine Ky under the innocuous title, “Music and Spatial Task Performance.”
⁵
Shaw, a physics professor who had shifted his interests to neuroscience, together with his student Xiaodan Leng, had developed a mathematical theory of how neurons in the brain work together. As a classical music enthusiast, Shaw noticed some similarities between the mathematical structure of classical pieces and the patterns his theory predicted would be found in the electrical activity of neurons. From this perceived similarity, he made the prediction that merely listening to music could enhance the function of one’s brain—but only the right kind of music.
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Shaw believed that Mozart had composed music that would “optimally resonate with the inherent internal neural language,” and that it would have the greatest enhancing effect. As he later wrote, “The magic genius of Mozart perhaps displayed a supreme use of the inherent cortical language in his music.”
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To help him test his theory, Shaw hired Frances Rauscher, a former concert cellist who had switched her profession to psychology, and together they conducted a simple experiment. Each of thirty-six college students performed three tests taken from a standard IQ test battery: “pattern analysis,” “matrix reasoning,” and “paper folding and cutting.” In the pattern-analysis task, subjects constructed objects out of blocks according to patterns they were given. In the matrix-reasoning task, subjects selected which of several shapes would complete a pattern composed of other abstract shapes. In the paper-folding-and-cutting task, subjects viewed a picture of an origami-like design, with dashed and solid lines showing where one would fold and cut the pattern. Then the subjects chose which of several pictures accurately showed what the paper would look like after being unfolded.

Before taking these tests, the subjects listened to one of the following recordings: ten minutes of Mozart’s “Sonata for Two Pianos in D Major (K.448),” ten minutes of “relaxation instructions designed to lower blood pressure,” or ten minutes of silence. The sonata is described as “gallant from beginning to end … one of the most profound and mature of all Mozart’s compositions.”
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According to the article, the subjects who did well on one of the tests did well on the others: There were significant correlations among all the tests, just as would be expected for the subparts
of an IQ test, or any test of general cognitive ability like the SAT. So Shaw and colleagues combined the three tests into a single measure of what they called “abstract reasoning ability” and transformed it to the scale of IQ scores, which have an average of 100 points for the general population. Then they compared the three listening conditions, and found that the scores after sitting in silence were 110, after listening to relaxation instructions they were 111, and after listening to the Mozart sonata they were 119.

Thus, listening to Mozart appeared to make the students smarter, by eight to nine IQ points. Although nine points might seem small, it’s not: An average person, who is by definition more intelligent than 50 percent of other people, would be more intelligent than 70 percent of other people after listening to the Mozart sonata. The simple tonic of ten minutes of classical music, if its effects could be harnessed, would propel a typical student past 20 percent of his or her relaxing or silence-enjoying peers, potentially turning Bs into As and failing grades into passing ones.

The media reported this new scientific finding with enthusiasm. “Mozart Makes You Smarter” read the headline in the
Boston Globe
. “Listening to Mozart is not only a music lover’s pleasure. It’s a brain tonic,” the article began.
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Less than a year after Rauscher, Shaw, and Ky published their article, music companies started creating new CDs to exploit the publicity, with titles such as
Mozart for Your Mind, Mozart Makes You Smarter
, and
Tune Your Brain with Mozart
. Ironically, most of these did not include the K.448 piano sonata that was used in the experiment, but it didn’t matter. Sales ran into the millions.
¹⁰
In his address to the Georgia state legislature, Zell Miller cited the Rauscher article: “There’s even a study that showed that after college students listened to a Mozart piano sonata for ten minutes, their IQ scores increased by nine points … no one doubts that listening to music, especially at a very early age, affects the spatial-temporal reasoning that underlies math, engineering, and chess.”
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