22 October 2012

Spatial awareness skewed by fear

by Will Parker

Fear can skew our perception of approaching objects, causing us to underestimate the distance of a threatening one, according to researchers from Emory University and the University of London. The findings, published in Current Biology, show that emotion and perception are subtly intertwined in the mind.

To explore our perception of when objects heading towards us will make contact, Emory's Stella Lourenco and London's Matthew Longo set up an experiment where participants made time-to-collision judgments of images on a computer screen.

The images expanded in size over one second before disappearing, to simulate "looming," an optical effect used instinctively by the brain to judge collision time. The study participants were instructed to gauge when each of the visual stimuli on the computer screen would have collided with them by pressing a button.

Lourenco said the participants tended to underestimate the collision time for images of threatening objects, such as a snake or spider, as compared to non-threatening images, such as a rabbit or butterfly.

The results challenge the traditional view of looming as a purely optical cue to object approach. "We're showing that what the object is affects how we perceive looming. If we're afraid of something, we perceive it as making contact sooner," Longo explained.

"Even more striking," Lourenco added, "it is possible to predict how much a participant will underestimate the collision time of an object by assessing the amount of fear they have for that object. The more fearful someone reported feeling of spiders, for example, the more they underestimated time-to-collision for a looming spider. Fear can alter even basic aspects of how we perceive the world around us."

The researchers note that it's unclear whether fear of an object makes the object appear to travel faster, or whether that fear makes the viewer expand their sense of personal space. "We'd like to distinguish between these two possibilities in future research. Doing so will allow us to shed insight on the mechanics of basic aspects of spatial perception and the mechanisms underlying particular phobias," Lourenco said.

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Source: Emory University