The internet boom has affected the way people perceive their health risk as they decide whether to see a doctor based on what they find online.
Now, a new study has revealed how checking out symptoms online affects individual health decisions.
Arizona State University psychologist Virginia Kwan and her colleagues found that the way information is presented-specifically, the order in which symptoms are listed-makes a significant difference.
"People irrationally infer more meanings from a 'streak'"-an uninterrupted series whether of high rolls of the dice or disease symptoms of consecutively reported symptoms. If they Google more symptoms in a row, the research found, "they perceive a higher personal risk of having that illness," she explained.
The study was conducted with Sean Wojcik of the University of California, Irvine, Talya Miron-shatz of Ono Academic College, Ashley Votruba of ASU, and Christopher Olivola of the University of Warwick
Surveying cancer-related sites, the researchers discovered that these vary in the way they present common and mild-or "general"-symptoms and more specific and serious ones.
To test how streaks affect risk perception, students were presented with lists of six symptoms of a fictional kind of thyroid cancer ("isthmal").
One group got three general symptoms (such as fatigue and weight fluctuation) followed by three specific ones (e.g., lump in the neck); another the reverse order; and the third group a list alternating between general and specific.
Participants checked off symptoms they'd experienced in the previous six weeks and then rated their perceived likelihood of having the cancer. The first two orders yielded similar risk ratings. But the ratings were significantly lower when the list alternated.
A second experiment compared lists of 12 or 6 symptoms, this time for a real cancer, meningioma. The three orders were the same as in the first experiment.
The effect of order disappeared for the longer, but not the shorter, list-that is, the influence of streaks was diluted when the list was longer. It's possible that even if a participant checked a series of symptoms-leading to suspicion of disease-boxes left unchecked offered reassurance of to the contrary, the researchers think.
The findings could prove useful for public health education, Kwan noted.
The study appeared in Psychological Science, a journal of the Association for Psychological Science.