Believing is not seeing

September 1, 2010 by
Filed under: Spinewave Bulletin 

You might think this is a fish, but actually it’s a bunch of pixels, behind which is a heap of binary code – ones and zeros. Our brains construct objects from a series of smaller building blocks, which is called our “visual vocabulary”. Most of the time what you’re seeing is not actually what you’re seeing, but a figment of your brain’s imagination.

It is in the visual cortex, located at the back of the brain, where much of the processing goes on. When items obscure each other, the brain must work out where one thing ends and another begins, and take a stab at their underlying shapes. One theory has it that to interpret what we see, we flick through a mental catalogue of objects we have seen before to try to find a best fit with the current image. If you don’t believe or like what you’re seeing, the brain will engage the “closure principle” and start making stuff up to fill in the blanks.

Our perceptions dictate how we’re going to respond to the world. A monocular viewpoint riddled with uncompromising bias will mean the individual’s brain is only going to perceive and process things in a certain way. Once the belief system is constructed based on hard wiring (genetics) and soft wiring (all learnings) then all observation will collect evidence to support that belief system – since that’s how the ego thinks it is the only way to survive – and there will never be enough evidence to the contrary. Even if there is an overwhelming plethora of it. Much like arguments you can never win with certain people. They argue to win, not to debate.

We have two streams of visual processing. The ventral pathway (front end) is necessary for perceiving or recognising an object, while the dorsal pathway (back end) deals with an object’s physical location in our visual field and, if we need to perform an action on it, guides the movement of our bodies. For this reason, scientists often refer to the two processes as the perception-action, or the “what-where” streams of visual processing. Actions will then be determined by the perceptions formulated. So if perceptions are distorted, people are not going to do smart things.

There are many visual disorders, typically caused by damage to specific parts of the brain:

  • Simultanagnosia – Seeing only one object at a time, even when viewing a scene comprising many items.
  • Integrative agnosia – Inability to recognise whole objects, tending to focus instead on individual features of an object.
  • Visual form agnosia – Inability to describe the shape, size or orientation of objects, yet exhibiting no problem in manipulating them.
  • Optic ataxia – Ability to report the shape and size of an object, though attempts to manipulate it are clumsy.
  • Prosopagnosia – Failure to recognise the faces of familiar people.
  • Pure alexia (aka agnosia for words) – Inability to identify individual characters or read text, even though subjects are sometimes able to write.
  • Agnosia for scenes – Inability to recognise known landmarks or scenes.
  • Colour agnosia – Ability to perceive colours without being able to identify, name or group them according to similarity.
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