It’s a familiar story. You feel a little under the weather, so you rush to WebMD or MedicineNet for a self-diagnosis. When you leave the sites, you’re convinced your headache and minor nausea must indicate brain cancer. This kind of Web-enabled hypochondria, dubbed “cyberchondria,” is becoming increasingly common as more people visit the Internet instead of the doctor’s office. According to a 2009 Pew poll, 61 percent of Americans use the Internet for medical information, and other recent studies have shown wide levels of increased anxiety triggered by this habit.
But why should simply reading an online write-up about, say, Hodgkin’s lymphoma convince us that we’ve fallen victim to the disease? A new study in the April 2012 issue of Psychological Science suggests that the irrational tendency at work in the brains of cyberchondriacs is the same as that in the brains of gamblers. Gamblers make the mistake of seeing patterns in a set of randomly generated events, deciding that a positive result on one or two rolls of the dice indicates that positive rolls of the dice will continue. For cyberchondriacs, that same tendency means deciding that hitting a streak in the list of symptoms (headache, followed by nausea, followed by fatigue) means you must also have all of the other symptoms in the list.
The researchers started by inventing a fictional type of thyroid cancer, then drew up three differently ordered lists of the same six symptoms. One list grouped the milder and more common symptoms (fatigue, shortness of breath) together at the top, with the more severe and rare symptoms (pain in the throat or neck, lump in the throat or neck) listed together at the bottom. The second list presented the more severe symptoms together first, followed by the milder ones. The third jumbled all the symptoms. Healthy subjects were given one of the three lists, required to check off their symptoms, and then asked how likely they were to have the cancer relative to the average American. Both groups reading lists of mild symptoms separated from severe symptoms were far more likely to believe themselves at risk for this fictional cancer than the group with the symptoms mixed up.
According to Virginia Kwan, a psychologist at Arizona State University and lead author on the paper, the results demonstrate the kind of unconscious pattern creation in which the human brain excels—and which frequently leads us astray when it comes to the basic logic of probability. The way gamblers say they have a “hot hand,” she says, cyberchondriacs believe they have “hot symptoms”: if they hit the first two in a list, they believe they must have the third one as well.
While Kwan hopes that sites like WebMD will use her results to help decrease anxiety among their customers, she points out that heightened anxiety isn’t always a bad thing. One example: during an epidemic outbreak. “It may be good to group the common symptoms together [in that situation] so that people pay more attention,” she says. In any case, next time your neck aches and WebMD suggests you may have viral meningitis, don’t panic. Sometimes diagnosis is best left to a medical professional.