To do: Fixate your gaze on the red dot, while paying attention to the solid grey circle (called an “artificial scotoma”. After a few seconds of steady fixation, the solid circle will fill in with the surrounding dynamic noise. Eye movements or blinks will cause the grey circle to reappear.
To notice: After the dynamic noise disappears (in 20 seconds), a powerful texture after-image takes the place originally occupied by the solid grey circle. This after-image may be dynamic: the so-called Twinkle effect (Ramachandran and Gregory, 1991) or static (Spillmann and Kurtenbach, 1992).
Dynamic filling-in occurs when eye movements are lacking or reduced. Our laboratory has showed that microsaccades (small involuntary eye movements that occur when we attempt to fixate) counteract visual fading and filling-in during visual fixation (Troncoso, Macknik and Martinez-Conde, 2008).
V. S. Ramachandran and R. L. Gregory (1991) Perceptual Filling in of Artificially Induced Scotomas in Human Vision. Nature, Vol. 350, pages 699–702; April 25.
L. Spillmann and A. Kurtenbach (1992) Dynamic Noise Backgrounds Facilitate Target Fading. Vision Research, Vol. 32, No. 10, pages 1941–1946; October.
X. G. Troncoso, Stephen L. Macknik and Susana Martinez-Conde (2008) Microsaccades Counteract Perceptual Filling-in. Journal of Vision, Vol. 8, No. 14, pages 1–9; November 4.