Jump Across the Gap! A New Type of Colour Spreading Illusion

The present article reports a new illusory colour phenomenon. There have been previous reports of illusory colours that spread to an area in contact with a coloured object (e.g., neon-like spreading). However, according to our informal observations as well as the experiments reported here, illusory colour spreads even if the coloured and noncoloured areas are separated by a gap. The contour-based perception account as well as the interaction of some components of surround suppression in the visual cortex were discussed as possibilities to account for the present illusion. The effect reported in the present study may provide suggestions for further understanding of colour perception.