The human mind contains
areas, or compartments, that perform specific mental tasks. For
example one compartment is used to understand language, another
to perceive smell. Some of these compartments are isolated from
other parts of the brain. They work on their own, not influenced
to goings on elsewhere.
This working in isolation is illustrated by the below common
optical illusion, called a Muller-Lyer illusion. Look at the
two horizontal lines.
The lines appear to be of different lengths. However they
are the same length. Measure them with a ruler to prove this
to yourself. It is a part of your mind that incorrectly perceives
the lines to be of different lengths.
The key here is not the erroneous perception itself. The key
is that even after the viewer knows the lengths are identical,
the lines still appear of different lengths. Even after the viewer
measures the lines and agrees 100 percent that the lines are
of identical lengths, the illusion still exists to this viewer.
This shows that the part of the mind that makes this perception
of the lines works in isolation, unaffected even by your conscious
knowledge that the lines are of identical lengths. If the part
of the mind that creates the perception was influenced by your
conscious knowledge, the misperception would dissapear once you
discovered the lines were the same length.
Muller Lyer illusion is real life:The center
vertival lines appear of different lengths, though they are equal.
Without the illusion being pointed out, the error goes unnoticed
in daily life.