Related Experiment Video
Updated: Aug 18, 2026

Visualizing Visual Adaptation
Published on: April 24, 2017
Perception of green and red under chromatic adaptation: the effects of stimulus size and eccentricity
1Department of Vision Sciences, University of Aston, Birmingham, England.
Abstract:
We measured thresholds for the perception of green and red light added to white, blue, green, yellow, or red adaptation fields presented at eccentricities of 0 to 70 degrees in the temporal visual field of two subjects. A series of stimulus sizes was used at each eccentricity to determine size-scaling factor E2--the eccentricity at which stimulus diameter has to be doubled in order to maintain foveal performance. For green light added to white or yellow, E2 varied from 3.1 to 41.5 degrees. When red light was added to white, yellow, or blue, E2 varied from 0.1 to 11.8 degrees. For red color in green and green color in blue or red there was no spatial scaling factor that would make performance independent of eccentricity. Our results suggest that E2 value for green and red perception depends on the state of chromatic adaptation and also shows marked interindividual differences.
Related Concept Videos
The Retina
Anatomy of the Eyeball
Photoreceptors and Visual Pathways
Depth Perception and Spatial Vision
Color Vision
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...

