It created a mirror image of the same arm in the place where the missing limb should have been, giving the visual illusion that it had been restored.

The trick was there was no movement, it was caused by a visual illusion known as the autokinetic effect.

The visual illusion community includes visual scientists, ophthalmologists, neurologists, and visual artists that use a variety of methods to help discover the neural underpinnings of visual illusory perception.

Their results showed an increased toe elevation in conditions where an illusion was perceived, leading them to conclude that there was a correlation between visual illusion and visuo-motor coordination.

All visual illusions rely on the fact that the brain constantly uses knowledge to add to and interpret what we can see.