On Science

Mice and Spiders and Bugs. Oh My!

Are animal phobias innate or learned?

By Josie Glausiusz | January 7, 2015
Photo by George Shuklin


At breakfast one morning when my twins were about 16 months old, my daughter started staring intently at something beneath her high chair. Following her gaze, I saw a mouse scrambling about on the carpet and shrieked. In response, my children screamed, too.

I felt terrible about triggering their distress, but the incident also prompted me to wonder how we develop a fear of harmless animals such as mice. Is it innate, or is it learned? If it is learned, had I implanted a permanent fear of mice in my curious daughter’s brain? I emailed Peter Muris, a professor of developmental psychopathology at Maastricht University in the Netherlands and the author of Normal and Abnormal Fear and Anxiety in Children and Adolescents (2007). He wrote back,

Dear Josie, the breakfast incident that you describe is a nice example of modeling or vicarious learning. That is, some children may acquire a fear of an unknown stimulus or situation by watching the parent or another person reacting fearfully to that stimulus or situation. There is research showing that this is a significant pathway to fear, although it is important to keep in mind that a modeling experience in itself is insufficient for creating a real anxiety disorder or phobia.

Oddly enough, although repulsed by mice and rats, I have a high tolerance for insects, spiders, and snails—and actively encourage my children to take a similar interest. Yet fear of spiders and other multilegged arthropods is common. What is the basis for this anxiety?

In 1992, psychologist Graham Davey (now at the University of Sussex in England) conducted a study of spider fears among 118 students at the City University London. Based on their answers to a questionnaire, he divided them into four groups: subjects who had always been afraid of spiders; subjects who had once feared spiders “but now felt relaxed towards them”; subjects who had once felt relaxed about spiders but now feared them; and subjects who had never feared spiders.

Surprisingly, there were no significant differences among the groups “on whether they had a traumatic experience in the presence of a spider.” Just eight out of the students described a traumatic incident involving a spider (for example, “A spider ran over my face when I was ill in bed, and I went hysterical.”). Second, while a large percentage of subjects in all groups had seen a close friend or relative being frightened by a spider, such experiences had no long-term effect: there were no significant differences among groups in the percentage of subjects who reported this exposure to fright.

Spider-fearing subjects—who were no more anxious, in general, than others in the population—did report that they were more likely to have at least one family member with a spider anxiety. The most frightening features of spiders, these people responded, were “legginess,” “sudden movements,” “speediness,” “hairiness,” and “crawliness.”

In a second study of 118 City University students, about half of whom participated in the first study, Davey found that spider-fearing subjects also had a “heightened fear” of animals that are typically considered fear- or disgust-evoking, such as rats, snakes, slugs, maggots, and worms. Not coincidentally, these are animals that are known to carry disease, or which live in disease-ridden places or in rotting food, or which are considered slimy or mucus-like. Therefore, his results suggest that certain animal fears do represent an innate, “harm-avoidance process” that can be reinforced by family influence.

The good news is that fear of insects and other arthropods can also be reversed, as science writer and curriculum developer Laurel Klein wrote to me via Facebook. Back in 2006, Klein had led school tours for pre-K to 8th grade children at the butterfly pavilion at Desert Botanical Gardens in Phoenix, Arizona. To prepare these “very urban” kids for encounters with erratically moving butterflies, she would ask the group, before entering the butterfly pavilion, “What should you do if a butterfly lands on your arm?” The “correct” response, she said, “was to turn to the imaginary butterfly on my arm, wave at it with my free hand, and cheerfully say, “Hello, butterfly.” She added, “If we didn’t cover this, there was a reasonable probability that the default response would turn out to involve swatting, shrieking, flailing, or all of the above.

(Klein also wrote:I’m not sure how much of it was the fact that we’re talking mostly about very urban kids here, but you could tell that the idea of a butterfly landing on them was scary to a lot more of them than I had expected. All of them seemed calmer after the ‘Hello, butterfly’ routine, however.”)

“The way in which we react to insects may be partly innate (stronger reactions to insects associated with real danger—bees, wasps, scorpions) or implied danger (anything quick and/or unpredictable in movements, bugs associated with decay or disease), Klein continued. “But it’s also partly learned, and it can be unlearned. Information and experiences go a long way toward the latter.”

That is, in fact, what Muris told me about mice. “P.S.,” he wrote in his email. “You can reverse the effect of a negative modeling experience by positive modeling (calmly and cheerfully handling a mouse in front of your child!).”

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