A visual illusion of relative movement in a pair of concentric rings composed of small diamond-shaped elements angled in different directions in the inner and outer rings (see illustration). If the image is moved back and forth relative to the eyes, while the gaze is fixated on the centre of the rings, the rings appear to rotate in opposite directions or contrary motion. The illusion is believed to be caused by elements in peripheral vision causing stimulation of direction-sensitive bar detectors in Area V1 of the visual cortex. Also called the rotating circles illusion or the counter-rotating circles illusion. See also movement illusion. Compare Ouchi illusion. [Named after the Italian vision scientist Baingio Pinna (born 1962), who discovered it in 1990, and the English psychologist Gavin J. Brelstaff (born 1961) who co-authored with Pinna the first major article on it in the journal Vision Research in 2000]
Pinna-Brelstaff illusion. If the image is moved back and forth relative to the eyes, the inner and outer rings appear to rotate in contrary motion.