Troxler's fading
Troxler's fading, also called Troxler fading or the Troxler effect, is an optical illusion affecting visual perception. When one fixates on a particular point for even a short period of time, an unchanging stimulus away from the fixation point will fade away and disappear. Research suggests that at least some portion of the perceptual phenomena associated with Troxler's fading occurs in the brain.
Discovery
Troxler's fading was first identified by Swiss physician Ignaz Paul Vital Troxler in 1804, who was practicing in Vienna at the time.[1]
Process
Neural adaptation
Troxler's fading has been attributed to the
Visual parallels
A similar 'sensory fading,' or
- First, one can mount a tiny projector on a contact lens. The projector shines an image into the eye. As the eye moves, the contact lens moves with it, so the image is always projected onto the same part of the retina;
- Second, one can monitor eye movements and move the stimulus to cancel the eye movements;
- Third, one can induce an afterimage, usually by an intense, brief flash, such as when one is photographed using a photographic flash (a form of stabilized retinal image that most people have experienced). This causes an image to be bleached onto the retina by the strong response of the rods and cones. In all these cases, the stimulus fades away after a short time and disappears.
The Troxler effect is enhanced if the stimulus is small, is of low contrast (or "equiluminant"), or is blurred. The effect is enhanced the further the stimulus is away from the fixation point.
Explanation of effect
Troxler's fading can occur without any extraordinary stabilization of the retinal image in
See also
- Cognitive science
- Lilac chaser – An illusion that involves Troxler fading
References
External links
- Troxler project: a research project on Troxler's fading Archived 2017-04-06 at the Wayback Machine