Leone Burridge

Chromatic induction from achromatic stimulus.

With particular spatial and value relationships, spectral colours may appear after a latency period.

The colours are enhanced with the superposition of a lighter value vertical grid with wider bands. Perhaps this is an example of articulation increasing the strength of an illusion.

Cohen and Gordon gave a review of the history of discovery and rediscovery of subjective colours in Psychological Bulletin, Vol.46 No 2, March, 1949. (With thanks to Professor John Mollon for alerting me to this article.)

In this article most cases cited involved movement and in the stationary images, involuntary eye movements were attributed as the cause, in a variation of the Benham’s Top phenomenon.

The present view is that the cause of the perception of these subjective colours remains unelucidated.

The illusory colours are more clearly seen on the actual paintings.