Study Finds People Who Fear Spiders Perceive Them as Larger Than They Actually Are

Posted on February 24, 2012

Spatula and a tarantulaA new study, published in the Journal of Anxiety Disorders, found that people who fear spiders see the spiders as larger than they actually are. Participants who feared spiders were asked to undergo five encounters with live tarantulas and then provide size estimates of the spiders after those encounters ended. The more afraid the participants said they were of the spiders, the larger they estimated the spiders had been.

The researchers recruited 57 people who self-identified as having a spider phobia. These spider fearing people were then exposed to tarantulas. Each participant interacted at specific time points over a period of eight weeks with five different varieties of tarantulas varying in size from about 1 to 6 inches long. The spiders were contained in an uncovered glass tank. Participants began their encounters 12 feet from the tank and were asked to approach the spider. Once they were standing next to the tank, they were then asked to guide the spider around the tank by touching it with an 8-inch probe, and later with a shorter probe.

During the encounters the participants were asked to rank how afraid they were on a scale of 0-100. After the encounters, the participants completed additional self-report measures of their specific fear of spiders and any panic symptoms they experienced. They were also required to estimate the size of the spiders (after no longer being able to see them) by drawing a single line on an index card to represent the length of the spider from the tips of its front legs to the tips of its back legs.

An analysis of the results showed that higher average peak ratings of distress during the spider encounters were associated with estimates that the spiders were larger than they really were.

Michael Vasey, professor of psychology at Ohio State University and lead author of the study, says, "If one is afraid of spiders, and by virtue of being afraid of spiders one tends to perceive spiders as bigger than they really are, that may feed the fear, foster that fear, and make it difficult to overcome. When it comes to phobias, it's all about avoidance as a primary means of keeping oneself safe. As long as you avoid, you can't discover that you're wrong. And you're stuck. So to the extent that perceiving spiders as bigger than they really are fosters fear and avoidance, it then potentially is part of this cycle that feeds the phobia that leads to its persistence. We're trying to understand why phobias persist so we can better target treatments to change those reasons they persist."

Photo: Michael Vasey, Ohio State University