In the study, psychologists created a fictional thyroid cancer and had subjects read descriptions of its symptoms. Some had the very general symptoms, things like fatigue and weight fluctuation, grouped together at the start. Others had those general symptoms interspersed with more specific problems such as a lump on the neck.

What they found was those that went through the general symptoms first were more likely to self-diagnose themselves with cancer..

The researchers think the phenomenon similar to what they call a “gambler’s fallacy,” where a streak of good cards irrationally convinces a gambler he’s more likely to continue winning. Except in this case, a streak of confirmed symptoms irrationally convinces the Web surfer he has cancer.

If anything, the study authors hope their work will give sites like WebMD a reason to consider restructuring how they present information.

“According to our findings, if the goal is to encourage people to seek medical attention, symptoms should be presented in a short list of general symptoms grouped together,” they conclude. If, however, the goal is to halt online hypochondria, the authors suggest taking the exact opposite approach and that “alternating specific and general symptoms is desirable.”

(h/t: Britt Peterson)