August 29, 2013
Back Off! Size Of Personal Space Larger For Those With Anxiety
April Flowers for redOrbit.com - Your Universe Online
Everyone has personal space, that bubble around our bodies that we don’t like invaded. This space is known by scientists as “peripersonal space.” Previously, researchers have considered that peripersonal space has a gradual boundary. New research from University College London (UCL), however, has given physical limits to the relationship between anxiety and personal space.
The findings, published in The Journal of Neuroscience, define the limit of peripersonal space surrounding the face as 8 to 15 inches away. The researchers also found the specific distance varies between individuals. For example, people with anxiety traits were found to have larger peripersonal space.
Dr. Chiara Sambo and Dr. Giandomenico Iannetti from UCL set up an experiment to record the blink reflex – a defensive response to potentially dangerous stimuli at varying distances from subject's face. The team compared the reflex data to the results of a self-reported anxiety test where the participants rated their levels of anxiety in various situations.
Participants who scored highly on the anxiety test reacted more strongly to stimuli 8 inches from their face than those who received low scores on the test. Those who reacted more strongly to further away stimuli were classified as having a large “defensive peripersonal space” (DPPS).
The researchers say that a larger DPPS means those with high anxiety scores perceive threats closer to their faces than non-anxious individuals – even when the stimuli is the same distance away. This suggests the brain controls the strength of defensive reflexes even though it cannot initiate them.
Dr Giandomenico Iannetti, Reader in Human Neuroscience, Physiology and Pharmacology at UCL, said, "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."
The 15 participants in the study, aged 20 to 37, had an intense electrical stimulus applied to a specific nerve in the hand, causing them to blink. This hand-blink reflex (HBR) is an autonomic response and is not under conscious control of the brain.
The researchers monitored the HBR with the subject holding their own hand at 1.5, 8, 15 and 23 inches from their face. How dangerous each stimulus was considered was determined by the magnitude of the reflex, with larger responses for stimuli further from the body indicating a larger DPPS.
The anxiety test was self-scored, with each participant predicted their anxiety level in a variety of situations. The researchers used the results to classify individuals as more or less anxious, and were compared to the data from the reflex experiment to determine if there was a link between the two tests.
The research team hopes the findings could someday be used as a test to link defensive behaviors to anxiety levels. They suggest such a link could be particularly useful in determining risk assessment ability in those with jobs that encounter dangerous situations such as fire, police and military officers.