What the Nose Knows - Avery Gilbert [27]
So strong is the conventional wisdom about the negative effect of smoking that researchers worry when they fail to confirm it. Take the case of a large population-based study in Skövde, Sweden. It linked decreased olfactory performance to several factors including being older, being male, and having nasal polyps. Smoking was not one of the factors. Similarly, diabetes and nasal polyps predicted complete anosmia, but sex and smoking did not. The authors didn’t find that smoking improved odor perception; they merely failed to find that smoking harmed it. One can see them bracing for a wave of politically correct indignation when they say, “The lack of a statistically significant relationship between olfactory dysfunction and smoking may be controversial.”
Blind Faith
When, at a party, I own up to being an expert on the sense of smell, I get peppered with questions. (I don’t mind this—if I’m not in the mood for Q&A, I tell people I’m “in the chemical business” and the conversation grinds to a halt.) People often ask about smell ability. Who is better: men or women? perfumers or normal people? Curiously, one comparison doesn’t come as a question but as an assertion. Wineglass in hand, someone will inform me in earnest tones that “blind people have a heightened sense of smell.” Others confidently assure me that “Helen Keller had an incredibly sensitive nose.”
Helen Keller has been dead since 1968, but remains a powerful symbol of the belief that blindness turns people into super-smellers by way of compensation. (The Marvel Comics hero Daredevil embodies the same idea.) Despite her iconic status, Helen Keller herself did not claim to have a supersensitive nose. In her famous essay “Smell, the Fallen Angel” she describes what she is able to smell. Amid lyrical, somewhat overripe prose (“Smell is a potent wizard that transports us across a thousand miles and all the years we have lived”), she gives specific examples of her olfactory ability. Let’s compare her talents to ours. Smells trigger memories—check. Approaching rainstorms have a smell—check. Can smell if a house is old-fashioned and long-lived-in—check. Can smell a person’s occupation (painter, carpenter, ironworker)—check. Close friends have distinctive odors—check. Babies smell sweet—check. Nothing extraordinary so far. Helen Keller does not sound like a nasal genius. Indeed, nowhere does she claim to have a more sensitive nose as a result of being blind, or that her sense of smell is better than that of sighted people. On the contrary, she writes, “I have not, indeed, the all-knowing scent of the hound or the wild animal.” She also says, “In my experience smell is most important.” It is not surprising that, being blind and deaf, she finds smell to be her primary way of sensing the world.
Helen Keller’s modest assessment of her own ability has done little to dampen enthusiasm for the idea of smell compensation in the blind. It seems so reasonable it must surely be correct. But is it? There is plenty of experimental evidence that addresses the question—in the last twenty years, six studies have compared smell in the blind and the sighted. Without exception, they find that the blind are no more sensitive than the sighted—both groups detect odors at about the same concentration. Nor do blind and sighted people differ in the ability to discriminate one odor from another. Even the brain waves triggered by odor stimulation are similar in blind and sighted people.
Blind people may have one advantage: in three of the six studies, they were better at naming odors. Even here, their success depended on cognitive factors such as memory rather than hyperacute perception. Based on her own words, and on what has been observed in experiments, Helen Keller’s ability to navigate the smellscape was not the result of