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Spiders actually look bigger to arachnophobes

By Cari Nierenberg

A spider doesn't look so itsy-bitsy to people who are petrified of them. In fact, a new study suggests that the more the eight-legged arachnid freaks someone out, the bigger that person perceives the spider to be.

People who were the most fearful of spiders tended to overestimate their actual size, Ohio State University researchers have found.

In the study, published in the Journal of Anxiety Disorders, scientists recruited 57 spider-phobic individuals. In three separate sessions over a two-month period, participants were asked to estimate the size of five different live tarantulas. It was actually part of the treatment they were receiving to get over their fear.

For each close encounter of the spider kind, arachnophobes were told to stand next to a glass tank and guide a spider around inside it with a probe. Participants also completed questionnaires in which they rated their fears, anxieties, and panic-related symptoms.

To estimate size, the spider-phobes would draw a line on a card to represent the length of the tarantula they had just seen.

"We found that some of our most fearful participants drew lines that were nearly three times as long as the actual spider," says Dr. Michael Vasey, a professor of psychology at Ohio State University, and the study's lead author.

Phobias reflect distorted thinking and perception, which leads to fear responses that are excessive given the reality of the feared object, Vasey explains.

In other words, fear makes the spider seem bigger, which increases a person's fear of it, which makes it look even bigger, which leads a person to remember it as larger than it is, so the fear persists.

So, Vasey says, a person who is spider phobic may not only see spiders as larger than they are. That individual may also believe spiders are much more likely to bite or be dangerous, or that encountering one would be terrifying. 

These mistaken beliefs are often perpetuated because the person avoids all contact with the feared object and is sheltered from learning the truth: Many spiders are completely harmless.

There's some evidence a tendency to overestimate is common to other phobias: People who are afraid of snakes as well as those who fear needles may also misjudge their length. And folks who are fearful of heights might say a balcony is higher off the ground than it is. 

But the good news is that many participants who were terrified of tarantulas conquered their fear in a remarkably short time. By working with a mental health professional trained in exposure therapy, "the vast majority of spider phobics in our study overcame their fear in less than two hours," says Vasey.