The British researchers who conducted the study said that their findings could be used to link defensive behaviour to levels of anxiety, particularly among those with risky jobs, such as fire fighters and police officers. People with anxiety perceive threats as closer, compared to those who are not.
In conducting the study, Dr. Chiara Sambo and Dr. Giandomenico Iannetti, from University College London, recruited 15 people ranging in age from 20 to 37 and gave them a test to rate their level of anxiety in certain situations.
In addition, the researchers applied an electrical stimulus to a nerve in each participant’s hand, which caused them to blink. This hand-blink reflex, which is not controlled by the brain, was monitored as the participants held their hand at four different distances from their face: ranging from about 2 inches to nearly 2 feet. By measuring the strength of their reflex, the investigators determined how dangerous the participants viewed each stimulus.
The study, published in the Aug. 27 issue of the Journal of Neuroscience, revealed that those who scored higher on the anxiety test reacted more dramatically to stimuli about 8 inches from their face compared with those who had lower anxiety scores. People who reacted strongly to the stimuli farther away were classified as having a large “defensive peri-personal space,” the study authors said.
Anxious people viewed threats as closer than those who were not anxious — even if the perceived threats actually were the same distance away, the researchers said. Although the brain does not trigger defensive reactions, the study authors said, it could control their intensity.
“This finding is the first objective measure of the size of the area surrounding the face that each individual considers at high risk, and thus wants to protect through the most effective defensive motor responses,” Iannetti said in a university news release.