FEAR OF DYING David G. Myers’s article, “The Powers and Perils of Intuition,” dealt in part with statistics; for example, women fear breast cancer more than heart disease but are more likely to die of heart disease than of breast cancer, and we fear planes more than cars, although more people die in cars than in planes. I think the author missed something central about how the brain assesses risk.
The brain does not make a fear assessment based on the likelihood of a particular event occurring; rather it does so based on the likelihood of dying if you should find yourself in a particular event. For example, when it comes to planes and cars, the brain isn’t concerned with how likely it is that you will be in one or the other. Instead it is saying, “If I am in a plane crash, I will certainly die. If I am in a car crash, however, there is some decent chance that I will live because people survive car crashes all the time. Therefore, planes are scarier than cars.” Along the same lines, cancer is famously lethal. Heart disease, on the other hand, feels survivable—plenty of people get heart disease and then change their diets or exercise or get bypass surgery and survive.
You can see why such thinking would be a good evolutionary mechanism: avoid the things that are most lethal regardless of how often they occur. And these fears are not set in stone. Pretend that through some scientific breakthrough, breast cancer becomes a manageable disease—a disease that you will have but that will not kill you. In that case, breast cancer would drop off the fear list even if the statistical incidence of breast cancer
remained the same as it is now. It is not about how often but how lethal.
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Matt Prager
Brooklyn, N.Y.
MYERS REPLIES: Research does confirm a corollary of Prager’s interesting conjecture: people make gut judgments about the likelihood of bad things happening based on their availability in our memories (a phenomenon called the availability heuristic).
Catastrophic events such as plane crashes and terrorist violence are vivid, easily recalled incidents. We are therefore inclined to have exaggerated fears of such events—which often kill people in bunches—and to underplay our vulnerability to more mundane risks, such as smoking, driving and other threats that claim lives one by one or in the distant future. The human mind, Oliver Wendell Holmes, Jr., noted, is disposed to reason dramatically, not quantitatively.
MIRRORS FOR STROKE We read with interest “Therapeutic Reflection,” by Ferdinand Binkofski and Giovanni Buccino, about the rehabilitation of motor function after stroke. The authors describe a treatment in which patients watch a videotape of movements being carried out properly.
We fail to understand why they did not mention our prior work on a method that clearly predates theirs. We reported at the Society for Neuroscience meeting nearly a decade ago
and in the journal Lancet in 1999 the striking recovery of function using visual feedback. In our therapy, patients try to move their paralyzed limb while watching the reflection of the unaffected limb in a mirror positioned sothat both limbs appear to be moving normally. Indeed, in a 1995 article in Nature we were the first to suggest the concept of using visual feedback as a powerful new tool for the rehabilitation of hemiparesis, or partial paralysis,
after stroke, based on our earlier work using mirrors to mobilize phantom limbs for pain relief. As early as 1994, one of us (Ramachandran) suggested using visual feedback—employing mirrors—for stroke rehabilitation in the International Review of Neurobiology,
Vol. 37, pages 291–333 (Academic Press).
Binkofski and Buccino used visual feedback from a video, whereas we used mirrors, but the principle is the same, and both procedures tap into the same neural system (“mirror neurons”), as suggested previously by us. The work of Binkofski and Buccino is to be applauded, but the general concept—the critical role of visual feedback—had already been established.
Vilayanur S. Ramachandran
Eric L. Altschuler
University of California, San Diego
JAILHOUSE BLUES
While reading “Rhythm and Blues,” by Ulrich Kraft, I found myself applying the ideas he presented to what I consider one of the most interesting paradoxes of our society. During my undergraduate study in psychology at the University of Montana in 2001, I encountered the statistic that an estimated 70 percent of the adult male prison population suffers from antisocial personality disorder. Yet we take these people and put them in an intensely
social situation wherein they have to rely every day on the goodwill of our society for everything they have.
Incarceration is also a situation in which they have no chance to learn or practice the social skills they are lacking and very little chance to be exposed to natural light. It would be interesting to see how the light therapy discussed in this article would affect this prison population.
Julie Kahl
Missoula, Mont.
MISSING THE POINT
Paul Raeburn’s article “Kids on Meds: Trouble Ahead?” presented a balanced view on the issue of drugs versus no drugs for childhood mental illness. Yet like nearly all of the current debate in the media, it does not explore the core cause of low serotonin or glutamate in our children’s brains. There are a host of pediatric disorders characterized by an imbalance in neurotransmitters that affect behavior, such as attention-deficit hyperactivity disorder (ADHD), autism and Asperger’s, learning delay, and oppositional
defiance disorder. We need to be asking why this is happening.
Several researchers, including Martha Herbert of Harvard University and Arthur Krigsman of
New York University, are looking into metabolic dysfunction as a driver for these disorders. These biomedical researchers are finding that a combination of factors may create “brain-immuno-gut” disorders; for example, dysfunctional gastrointestinal health could lead to poor nutrient status and toxicity, altering the brain and causing autism, ADHD, learning delay, depression, anxiety and more.
The deterioration in the health of our children attributed to pollutants, refined foods and overmedication is as big an issue as global warming is. Please consider researching and writing about this topic.
Leslie Embersits
Sydney, Australia
POLITICAL UNREST I did a double take while reading “Right-Side Up,” by Vilayanur S. Ramachandran and Diane Rogers-Ramachandran [Illusions], and it was not because of the interesting visual figures illustrating the article. My surprise was due to the authors’ choice of the word “vapid” to describe George W. Bush’s expression. Even as a Democrat, I find that word choice disappointing and out of place in your magazine. I would have expected more pro fessionalism from Ramachandran, whom I respect for his insightful teaching about pain and brain disorders. I also hope that Scientific American Mind can avoid becoming a snide, liberal political magazine and return instead to embodying its tagline, covering “thought, ideas and brain science.”
Sarah Whitman
Drexel University College
of Medicine
ERRATA The painting by Salvador Dalí on page 63 (“Rhythm and Blues,” by Ulrich Kraft) was inverted.
In the further reading for “Betting on Consciousness,” by Christof Koch and Kerstin Preuschoff, the citation for Persaud et al. lists the incorrect month of publication. “Post-Decision Wagering Objectively Measures Awareness” appeared in the February 2007 issue of Nature Neuroscience. The paper also appeared online January 21, 2007.
