Floating Dice: Optical Illusions

It may seem like an impossible construction. In this video, stacked-up dice seem to float on top of each other. They even appear to hover when viewed up close, until a hand appears on camera to reveal the visual trick. Were you fooled by the illusion?

This set-up, recreated by illusion fanatic Rex Young, is a classic devised by legendary illusionist Jerry Andrus. You may be familiar with the effect as it's one example of the hollow mask illusion.

When viewing a concave mask, most people perceive a convex face. It's our brain's most common interpretation of the visual information since we're so used to seeing people's everted faces.

The late British psychologist Richard Gregory studied the illusion and saw it as evidence for the top-down processing of visual information. Interestingly, a recent study found that people with schizophrenia are immune to the effect, raising the possibility that the illusion could be used as a diagnostic tool.

The dice arrangement was one of our favourite illustrations of this illusion, but we came across a lot of other examples. Have you seen a version of the effect that you find particularly effective? Let us know in the comments below.