Psychedelia 5
Acrylic on canvas
18" X 24"

Psychedelia 5 shows a phosphene-rich background beside a blue drapery, with a bright, nearly fully formed bagel illusion. It also features a reverse-color aura, such as appears next to every sharp edge a person sees.

Unlike phosphenes, which arise spontaneously within the visual system, auras come from photobleaching of rhodopsin within the rod and cone cells in the retina. Photosensitivity of retinal cells occurs when rhodopsin molecules respond to photons by switching between a light-sensitive conformation and a light-insensitive conformation, releasing energy in the process. Those cells have reduced sensitivity until they "pump" their rhodopsin molecules back up to their light-sensitive conformation.

The auras appear when eye movements shift the image on the retina slightly. In this case, the gaze has shifted slightly to the right, uncovering part of the retina that was previously protected from photobleaching by the dark-colored drapery. The cells in that area are, therefore, overly sensitive compared to cells that have been looking at the brighter background, and the scene looks lighter there.