Gazing at colored boxes with black stripes cause long-lasting halo effect on white boxes with stripes. I tried it last night and the effect is stronger this morning!
It is called the McCollough Effect, and was originally described by Celeste McCollough in a paper in Science in 1965. It has been the focus of on-going investigation ever since.
The effect typically lasts for hours, or even overnight. The duration can be changed by the consumption of coffee and other psychoactive drugs. One paper found that it is stronger in extroverts than introverts, and might be a reliable test for extroversion.
The precise cause of the effect is unknown, and currently under investigation. It is not a simple case of fatigued neurons: there are neurotransmitters involved and appear to be responsible for the long-lasting nature of the effect. It probably takes place in the V1 processing stage of visual information. This is the first image processing after the signal leaves the retina in the eye. The edge detection circuits somehow become associated with the color. At this stage the processing is monocular: the images from the two eyes have not been combined.
Reader comment:
alainsane says:
If you don’t believe your eyes, tilt your head 45 degrees in either direction while maintaining eye contact. If you’re like me, you’ll see the green and magenta hazes disappear.