When Noga Cohen, a grad student at Israel's Ben-Gurion University, spotted a spider one day, arachnophobe and fellow student Tali Leibovich freaked out about its size. Cohen thought that odd, because the eight-legged arachnid looked tiny to her, reports Live Science. And so a study was born. They set out to see if people's fear of spiders can influence perception of the creature's size, and that appears to be the case. "Although individuals with both high and low arachnophobia rated spiders as highly unpleasant, only the highly fearful participants overestimated the spider size," says Leibovich in a statement. How the researchers tested this: Figuring women were more averse to spiders than men, they divided 25 women into a low-fear group and a high-fear group. From there, they had the subjects review pictures of butterflies, birds, and spiders and estimate their sizes, using a sliding scale with a fly on one end and a lamb on the other.
Although both groups found the spiders unpleasant, only the fearful group overestimated their size compared to butterflies, the researchers report in Biological Psychology. To check if this perceptual phenomenon happens with other creepy-crawlies, the researchers duplicated the experiment using wasps, beetles, and butterflies—and found that the group more fearful of wasps didn't overestimate their size compared to the butterflies. They did overestimate the size of the beetles, but based on exit interviews, the researchers think it's because most subjects IDed the beetles as more phobia-inducing cockroaches. The results raise a question, says Leibovich: "Is it fear that triggers size disturbance, or maybe the size disturbance is what causes fear in the first place?" (How to cure a spider phobia in two minutes.)