Experiment with babies, spiders and snakes surprises researchers

Researchers from the Max Planck Institute, the University of Vienna, and Uppsala University found that six-month-old infants react with pupil dilation to images of spiders, even without prior experience. In the experiment, babies were shown photos of spiders and flowers; pupils dilated more strongly when seeing spiders. To control, parents wore dark glasses. A separate experiment with snakes and fish showed pupil dilation only when one type of animal was shown. Lead researcher Stefanie Hoehl links this to an evolutionary predisposition of the brain, but critic Wolfgang Denzer points to visual complexity. Clinical phobias develop later.

A group of researchers from the Max Planck Institute, the University of Vienna, and Uppsala University discovered that six-month-old infants show a distinct physiological reaction—pupil dilation—to images of spiders, even if they have never encountered them in reality. The results were published in the journal Frontiers in Psychology. During the experiment, children were shown photographs of spiders, alternating with images of flowers matched for size and color. Special equipment recorded changes in pupil size. To rule out parental influence, adults wore dark glasses. Pupils dilated more strongly when seeing spiders than when seeing flowers. The experiment with snakes and fish yielded less clear results: in the first phase, there was no difference, but upon repeated testing, when children were shown only one type of animal, pupils dilated when seeing snakes. Lead researcher Stefanie Hoehl suggests that the brain is evolutionarily tuned from birth to quickly detect dangerous shapes, facilitating learning and protection. However, the scientific community is divided: Wolfgang Denzer believes that pupil dilation may be related to the visual complexity of the image, not emotions. Observations of children aged one and a half to three years show that they are more likely to show curiosity toward live spiders and snakes. The authors emphasize that clinical phobias develop later, and the focus is on the brain's predisposition to concentrate attention on certain objects.