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Biology Articles » Zoology » Ethology » When In Danger Humans Are Similar To A Deer In The Headlights
Standing still when a threat is detected is a defensive, protective reaction. This ancestral and automatic behavior allows the prey to stay unnoticed by a potential predator. A new study published in Psychophysiology finds that humans, like many other complex animals, freeze when encountering a threat.
Forty-eight male volunteers stood barefoot on a stabilometric platform, to measure balance and body sway, and viewed twenty-four pictures from three different categories. They were: pleasant (sports), neutral (objects), and unpleasant (injured or mutilated humans). Posturographic and electrocardiographic recordings were collected.
The author found a significant reduction in body sway along with increased muscle stiffness following the unpleasant/mutilation block of pictures compared to the neutral pictures. The number of heartbeats per minute was also lower after viewing the mutilation pictures than after looking at the others.
"This pattern resembles the 'freezing' and 'fear bradycardia' seen in many species when confronted with threatening stimuli, mediated by neural circuits that promote defensive survival," author Eliane Volchan explains.
Source: Blackwell Publishing Ltd.. June 2005.
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