A double neon colour illusion.

A new visual illusion is presented. When two neon-coloured illusory bands overlap each other, the filling-in at the region of overlap is perceived as different from those of the overlapping bands, resulting in an additional illusory shape at the region of overlap. An experiment with ten naïve participants was performed to measure the illusory percept. The results show that illusory surfaces may interact with each other, and, to a certain extent, create new illusory percepts.