Following your heart, not your head

Evaluating risks:When it comes to making tough decisions, we instinctively prefer using our hearts over our heads. For most people, emotional responses to an issue are much more powerful than rational decision-making based on numbers.

The AAAS meeting under way in San Francisco heard a number of researchers discussing how we cope with perceived risks in a session entitled "Numbers and Nerves: Effect and Meaning in Risk Information".

Is it more risky to face a one in 10 chance of a disease or a 10 in 100 chance? Research has found that not all people recognise that these two risks have an equal chance of happening.

"People tend to have a hard time evaluating numbers, even when the numbers are clear and right in front of them," said Dr Joseph Arvai, an environmental science and policy researcher from Michigan State University.

"In contrast, the emotional responses conjured up by problems like terrorism and crime are so strong that most people don't factor in the empirical evidence when making decisions."

The human brain readily processes emotional and empirical information, but for most people the rational response is overwhelmed by the emotional response to risk.

Dr Arvai and a graduate student, Robyn Wilson of Ohio State University, tested this response by asking subjects to consider two risk scenarios, one involving ordinary crime, such as theft, and the other involving damage caused by deer, as in collisions with cars. They asked participants which risk required the quicker response.

Theft is comparatively rare in parks populated by deer while injury and damage caused by deer is significant. "But because crime incites such a negative emotional response from most people, it consistently received more attention, even when the numbers showed that the risks from deer were much worse," Dr Arvai said.

This phenomenon also has a chilling potential with regard to genocide, said Dr Paul Slovic, a University of Oregon psychologist and president of Decision Research, a non-profit research institute. His studies have found that once the number of deaths begins to climb our level of indignation does not follow suit.