English: A figure similar to that of Figure 1 of Broerse, Vladusich, and O’Shea (1999), demonstrating what became known as the watercolor illusion. The vertical gratings are black and white with a thin line of red along each black bar. The horizontal gratings are black and white with a thin line of green along each black bar. The illusion is that the red and green appear to speed over the black and white regions of the vertical and horizontal gratings respectively.

Reference

Broerse, J., Vladusich, T., & O’Shea, R. P. (1999). Colour at edges and colour spreading in McCollough effects. Vision Research, 39, 1305-1320. doi:10.1016/S0042-6989(98)00231-4