Ehrenstein illusion

The visual phenomena was studied by the German psychologist Walter H. Ehrenstein (1899–1961) who originally wanted to modify the theory behind the Hermann grid illusion.

In the discovery of the optical illusion, Ehrenstein found that grating patterns of straight lines that stop at a certain point appear to have a brighter centre, compared to the background.

[2] Sometimes the "Ehrenstein" is associated with an illusory contour figure where the ends of the dark segments produce the illusion of circles or squares.

[5] In 1954, further variations of the original Ehrenstein illusion found that the sides of a square take on an apparent curved shaped when placed inside a pattern of concentric circles.

[1] It assumes a bottom up approach to complex thinking, meaning people take in and process available information before arriving to a final conclusion.

If sightings can not be explained immediately, the brain invents alternative interpretations which have no factual or perceptual evidence behind it as a way to fill in the gaps.

According to the German neurologist Lothar Spillman, further research is required to create a new theory which accounts for both the characteristics of the illusory stimulus and the perceptual processing of the individual.

Gestalt psychology assumes that the brain must have some kind of previous expectation which forms the basis of the illusion, before a conscious interpretation of the stimulus takes place.

However, recent computational studies seem to suggest that the representation of the stimuli is built up from the brain through the competition and cooperation of visual neurons.