People suffering from arachnophobia, a fear of spiders, overestimate spider size in comparison to other animals that they are not afraid of, according to researchers from Ben-Gurion University of the Negev (BGU). The new findings, gathered from two experiments that measured attractiveness and the role of self-relevance in the size estimation of neutral animals compared to aversive animals, could be useful in the treatment of phobias.

"We found that although individuals with both high and low arachnophobia rated spiders as highly unpleasant, only the highly fearful participants overestimated the spider size," Tali Leibovich, lead author of the study, said in a press release.

The team gathered female BGU students and gave them a questionnaire in order to measure their fear of spiders and separated them into two groups: those afraid of spiders and those not.

The results from the first experiment showed that, despite both groups rating spider pictures as more unpleasant than the others, only the group afraid of spiders overestimated their size compared to butterflies. Furthermore, additional experiments revealed that size estimates were affected by the level of unpleasantness of the spider and the level of fear that the participant had of spiders.

"This study revealed how perception of even a basic feature such as size is influenced by emotion, and demonstrates how each of us experiences the world in a unique and different way," said Leibovich.

"This study also raises more questions such as: Is it fear that triggers size disturbance, or maybe the size disturbance is what causes fear in the first place? Future studies that attempt to answer such questions can be used as a basis for developing treatments for different phobias," she concluded.

The findings were published in the Jan. 21 issue of Biological Psychology.