Butterfly wing patterns create motion illusions like barber pole

A study by researchers at the universities of Exeter and Essex suggests that some butterfly wing patterns can confuse predators by making the insects’ direction and speed appear different from their actual movement. High-speed recordings of butterfly takeoffs, bird-vision models and simulations of hundreds of species indicated that the shifting stripes and spots create misleading motion cues, much like the barber-pole illusion. In a touchscreen experiment, volunteers chasing virtual butterflies tended to aim behind them, with larger errors for patterns that produced stronger illusions. The findings offer a possible explanation for how conspicuously marked butterflies can evade birds and may also shed light on similar motion-dazzle patterns in other animals.