Related Experiment Video
Updated: Aug 13, 2026

Visualizing Visual Adaptation
Published on: April 24, 2017
Implications of the Craik-O'Brien illusion for brightness perception
1Department of Psychology, University of Western Australia, Perth.
Abstract:
Measurements are reported for detection thresholds of high and low-pass filtered squarewaves, and for brightness matches of those waveforms. The threshold measurements agree closely with those of Campbell, Howell and Johnstone [J. Physiol., Lond. 284, 193-201 (1978)]: contrasts at which a high-pass squarewave was indistinguishable from an unfiltered squarewave could be well predicted from detection thresholds for an appropriate low-pass squarewave. However, the brightness of high-pass squarewaves (the "Craik-O'Brien illusion") was not related to the threshold measurements. Brightness was virtually constant with spatial frequency, even at spatial frequencies 10 times higher than the region of the low frequency cut. Brightness depended strongly on contrast, being relatively greater at low than at high contrasts. The results can be well accounted for by a recent theory of edge detection, and the existence of parallel channels in vision.
Related Concept Videos
Cause and Effect
Anatomy of the Eyeball
Photoreceptors and Visual Pathways
Color Vision
Factors Affecting Perception
An illustrative example of a perceptual set is the scenario where an airline pilot told...
Perceptual Constancy
Size constancy is the recognition that an object remains the same size, even when its image on the retina changes. For instance, a bus is perceived to be large enough to carry people, even if it looks tiny from...

