What butterfly wings have in common with barbershop poles

What happened

Wing patterns, flight dynamics create "motion dazzle" effect, make it harder to gauge speed, direction. Old-fashioned striped barbershop poles turn in place on a vertical axis, but humans typically perceive the stripes moving upward rather than turning with the pole.

It's a well-known visual illusion arising from processing biases in human vision. According to a new paper published in the journal Nature, a similar effect could explain how butterflies often evade predatory birds: Their flight patterns and wing patterns combine to make it hard for predators to accurately gauge speed and direction.

"The stripes and spots on many butterflies’ wings interfere with the way visual systems try to guess the direction and speed of moving things, boosting false motion cues while hiding the butterfly's true heading," said co-author George Hancock of the University of Exeter in Cornwall. Butterfly wings have long fascinated scientists, ever since the first documentation of the growth of said wings back in 1938.