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Human Fear Changes as Predator Gets Closer

Can Fright Turn Hair Suddenly White?

A study of subjects playing a Pac-Man-esque computer game reveals that fear resides in different parts of the brain depending on the proximity of a threat.

When humans are faced with some sort of threat, such as a virtual munch-monster, they alter their behavior depending on whether the threat is distant (steering well clear of a predator's space) or nearby (running for one's life).

To see what is going on in the brain when a threat looms, researchers at the University College London created a computer game akin to Pac-Man where participants were chased through a maze by a virtual predator. If caught by the virtual beast, they would receive a very real mild electric shock. The participants' brain responses were measured with a brain-imaging fMRI machine.

When the predator was far away, parts of the brain's prefrontal cortex (just behind the eyebrows) showed activity. Activity in this area, which helps control response strategies to threats, increases during anxious moments.

But when the predator moved closer, brain activity shifted to a region of the brain responsible for more primitive behavior, such as quick-response survival mechanisms that include fight, flight and freezing.

"The most efficient survival strategy will depend on the level of threat we perceive," said study leader Dean Mobbs of UCL. "This makes sense as sometimes being merely wary of a threat is enough, but at other times we need to react quickly."

The study is detailed in the Aug. 24 issue of the journal Science.