No this isn’t an animated gif… its just your eyes playing tricks on you.
This is known as a peripheral drift illusion (and this particular one is called “rotating snakes”). The illusion works in part because of the way our eye moves — when we’re looking at something, we may think that our eyes are still, but there is actually an involuntary wobble to our eyes that scans over an entire image. These eye movements are known as saccades.
Aside from causing optical illusions, saccades can play an important role in how we understand autism.
Karen Pierce, a researcher at UC San Diego’s Autism Center for Research, has been developing new ways to track these eye movements in toddlers. Since autism is usually diagnosed at 2-3 years of age, she has focused on how they observe faces and geometric patterns.
Part of the diagnosis is if these eye movements happen less with the geometric shapes, then there is a higher chance the child has the disorder. Pierce explains:
“It was almost as if they got ‘stuck’ and didn’t move their eyes as much as typical toddlers when viewing geometric patterns. The geometric patterns were apparently very absorbing to them.”