Study Finds 6-Month-Olds’ Pupils Dilate 0.14 mm for Spiders, Not Just 0.03 mm for Flowers
Updated
Updated · spacedaily.com · Jul 25
Study Finds 6-Month-Olds’ Pupils Dilate 0.14 mm for Spiders, Not Just 0.03 mm for Flowers
1 articles · Updated · spacedaily.com · Jul 25
Summary
Sixteen 6-month-old babies in a 2017 study showed larger pupil dilation to spider photos than to matched flower photos—0.14 millimetres versus 0.03—suggesting higher arousal rather than demonstrated fear.
Researchers tried to isolate that effect by equalizing color, luminance and image size, using infrared eye tracking, and blocking parents from seeing the screen to prevent babies from reacting to adult cues.
Snake results were mixed in the first session—0.16 millimetres for snakes and fish alike—but a second test with 32 more infants separated the categories, with snakes at 0.29 millimetres versus 0.17 for fish.
The paper argues for “prepared learning,” an early attentional bias that could make fear easier to acquire later, while noting infant fear itself is not established and toddlers often approach live snakes and spiders.
Interpretation remains contested because the samples were small and critics say pupil dilation could reflect visual complexity or general animal salience, not an evolved threat detector specific to spiders and snakes.