The more afraid someone is of a spider, the bigger they estimate the spider’s size, according to new research from Ohio State U.

In a study published in the Journal of Anxiety Disorders, a group of psychologists recruited 57 people who were clinically afraid of spiders to interact five times with tarantulas, which were in uncovered glass tanks. Participants were asked how afraid they were on a scale from 0 to 100 after standing 12 feet away from the spiders and after touching the spider with an 8-inch or shorter probe.

Afterward, they were taken away from the tarantulas and asked to draw a line on a sheet of paper representing how big they thought the tarantula was.

“Some people drew lines up to two times as big as the spider was,” said Michael Vilensky, co-author of the study and graduate student researcher at Ohio State U. “The average fearful person did not overestimate the size of the spider, but the very fearful did.”

He said the new research shows there may be a link between the parts of the brain that control visual connection and the parts that control fear and anxiety.

“When you start feeling afraid, that fear system starts talking to your visual perception. It is telling the brain to get away from there,” he said.

U. Oregon psychology professor Paul Dassonville said the study is similar to previous research that found people who are afraid of heights tend to overestimate the height of a balcony.

“It’s not surprising that our emotions affect our perceptions,” Dassonville said. “People have the general perception that when they look at the world, they see it how it is, but that’s been proven not to be true.”

He cited other studies that have found people overestimate the steepness of a hill depending on how tired they feel. With the new research on phobias, he said psychologists are finding more about how the brain can be fooled by context.

Vilensky said his team has already conducted follow-up studies; in one study, researchers found that people overestimated the size of a spider even while they were looking at it. He also said that fear made people overestimate the size of other objects, such as a block or a plastic flower.

“When someone’s afraid, it’s almost like this magnification effect happens, and they start seeing things differently,” he said.