Spiders appear larger to those who fear them

Ron Weasley's high-pitched squeals demonstrate all too well how the dire fear of spiders can manifest itself. Recent psychological research demonstrates that individuals who fear spiders tend to overestimate the size of these creatures and perceive them as physically larger than their actual size.

Researchers at Ohio State University recruited 57 people who self-identified as having a spider phobia and exposed them to tarantulas that were between one to six inches in size. The participants were instructed to approach an uncovered glass tank where the spiders were held, from a distance of 12 feet away.

Once at the tank, the participants guided a spider around the tank with a probe. During their first encounters with the spiders, the participants were given an eight-inch probe, but the size of the probe was gradually decreased as the eight-week study went on.

After each encounter with a spider, participants rated the fear they experienced on a scale of 0-100. They also described their fear of spiders, any symptoms of panic they felt during the interaction and thoughts about reducing fear during future interactions.

Perhaps most telling of the research's findings was a task in which participants had to draw a line indicating the size of the spider after the interaction was over and the tank was covered up. The line was supposed to measure the length from the tip of the spiders front to hind legs.

The results revealed that arachnophobic individuals tended to overestimate the size of the spiders, and that the greater the fear of the spider, the larger the subsequent line drawn. Remarkably, the most fearful subjects drew lines that were about 50 percent longer than the actual size of the spider they had encountered.

Furthermore, the experiment was repeated while the spiders were not covered up, and the participants still overestimated the size of the spiders. This shows that perception was actually altered for individuals experiencing arachnophobia.

Although a fear of spiders is not particularly life-changing, researchers are applying the findings of the study to more pertinent fears. For example, individuals who fear needles similarly perceive a needle to be larger than it actually is, which can lead to an interference with their health care. Another example is the fear of heights, in which individuals tend to perceive their distance from the ground to be larger than it is in reality.

Exposure therapy is one of the ways in which individuals suffering from phobias are treated. Although scientists are unaware of the scientific reasoning for this method's success, exposure therapy can cure phobics by gradually subjecting them to their fear; in this case subjects became less afraid after interacting with the spiders over the course of eight weeks.

Researchers are hoping to apply their understanding of fears from this study in order to benefit people suffering from fears that interfere with daily life. Their findings could potentially enhance treatment targeted at patients who experience altered perception due to a fear.