Investigating the Mechanisms Underlying Visual Illusions: Munker-White-
like Illusions without T-Junctions

Arash Yazdanbakhsh
Department of Cognitive and Neural Systems
Boston University

We perceive scenes so easily that we ignore what a complex system the
visual system is. Because so many parts of our brain are dedicated
to vision, seeing becomes such a simple and effortless task for us that
we may think a simple phenomenon is going on.

Our brain knows many tricks to handle a scene. "Tricks" are necessary
because we are not always presented with a "clean" version of an object.
Sometimes it is occluded partially; sometimes the illumination condition 
is not so good, etc.

Visual illusions, which are sometimes used as a tool for entertainment, 
are marvelous tools to investigate the tricks our brain uses to analyze 
a visual scene. Not only do they expose the underlying mechanisms of our
visual system, but they also reveal its limitations and unexpected
properties.

One of the illusions, which was discovered lately by Munker around 1970
(and White around 1980), is clearly extraordinary among similar
illusions and attracts lots of attention for its assumed underlying 
mechanisms. Here, we create a special version of it which lacks a 
T-junction, a clue which is considered necessary to create the illusion.