People poor at self diagnosing illness on web: study

Researchers from Hong Kong University of Science and Technology found that using Google to diagnose illnesses could in fact be a very bad way of getting appropriate medical treatment, the 'Daily Mail' reported.

This misdiagnosis takes two main forms -self-positivity, where we overestimate the risks of falling prey to an illness, and self-negativity, where the opposite is the case.

People may interpret symptoms which in someone else might seem like indigestion as a sign they are having a heart attack, the report quoted NBC News.

The scientists used this sort of finding to develop a more systematic study of how people perceive their chances of illness.

They gave college students information on various diseases, telling them both how common they are among the whole population ('base rate') and the details of one specific person's health profile ('case risk').

If that person was a stranger, the test subject would tend to rely on the base rate, using a statistical approach.

But if asked to judge their own risk of exposure to disease, the participants primarily used the case risk.

That means that for conditions whose base rate is relatively low, people are more likely to believe that they are affected than others are.

Conversely, it also means that individuals might underestimate their chances of suffering from relatively common illnesses.

This is why, for example, people are often happy to shake off seasonal flu symptoms, claiming to be 'under the weather' instead, but during an outbreak of swine flu many more people think they are affected than actually are, the report said.