According to experts, more than 60 percent of Americans get health information online and many decide to seek medical care based upon what they read.

Researchers parlayed this observation to study if the manner in which online information is presented makes a difference for individual health decisions.

In the study, Arizona State University psychologist Dr. Virginia Kwan and her colleagues discovered that the way information is presented — specifically, the order in which symptoms are listed — is very important.

“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 check off more symptoms in a row, the research found, “they perceive a higher personal risk of having that illness.”

During the research, investigators reviewed the manner in which cancer-related sites present information. They determined sites differ in the way they present common, mild 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.

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.

Researchers believe that even if a participant checked several symptoms, an interruption in boxes checked provides reassurance or reduces perception of seriousness.

The findings could prove useful for public health education, Kwan says.

For some illnesses, earlier medical attention can literally be life-saving — a case for grouping dangerous symptoms together to heighten the perceived seriousness of the condition.

Conversely, people often go to physicians fearful that they have a very rare disease — a situation where spacing of serious symptoms could give individuals a better view of risk.

Reaching particular populations is also a public health challenge. “College students think they are invincible,” said Kwan.

“We now know that the way information is structured can help them realize there are diseases that don’t discriminate.”

The study appears in Psychological Science.

Source: Association for Psychological Science