Stare at the ellipses in this video and you'll start to experience trippy effects. The illusion, developed by vision researchers Gideon Caplovitz and Kyle Killebrew of the University of Nevada in Reno, features curved shapes spinning at a constant rate where changes in contrast, width and colour alter your perception.
At first, a single thin ellipse multiplies. If you fix your eyes on the centre of the screen, dark smudges may appear to blot out the center of the ellipses as your eyes are quickly exposed to stimuli with highly contrasting colours. Next, the shapes gradually become plumper, a transformation that makes the objects seem to slow down and rotate more fluidly. The animation then appears in different colours which seems to enhance the effect. Focussing on the colourful ellipses while the colours fade can also make them turn into polygons, a change that seems to occur at different times from person to person.
According to Caplovitz, the apparent change in speed is caused by how we sample information around us to detect movement. As the ellipses become chubbier, their shape weakens the sense of motion and they appear to move more slowly compared to their elongated counterparts. When colour is added into the mix, it also distracts from picking up movement. As the shapes become nearly circular, they seem to roll like jelly due to ambiguous information about their rotation.
The shape-shifting effect induced by colour was a surprise to Caplovitz. Although he was able to identify that it occurs when all colours look equally illuminated, he is still puzzled by individual variations in perception. "What's really neat is that it can be unique for every person," says Caplovitz. He hopes to hone in on the moment when the distortion looks most extreme for different people.
Were you able to see any or all of these effects? Let us know in the comments section below.
If you enjoyed this illusion, watch dizzying silhouettes change direction or spot the spinning stingray in another brain trick.
http://www.newscientist.com/blogs/shortsharpscience/
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