Monday, 10 December 2007

What is perception?

What is perception?
As humans, we do not directly experience our exterior environment. Rather we filter and examine signals that we model into an inspiration representing the external environment and form internal representations from these prompts. Due to the involuntary nature of this process, we require psychological reminders from parables and perceptual illusions.

A raison d'ĂȘtre that differentiates our interior representations from the exterior environment derives from human sensory limitations. Physiologically, humanity has evolved to effectively respond to its internal models. In cases of ambiguity, numerous internal models may present themselves. In these cases, the human active perceptual system can switch through these models in a manner that overrides conscious control. In selected instances, our interior representations or models do not reflect the external reality resulting in a perceived visual illusion.

Homo Sapiens often forgets the fact that we are not in direct contact with our external environment and witnesses errors in perceptive reality as truth.

The early philosopher Plato or the “wide, broad-browed” (or Aristocles as he was truly named) asked us to imagine a young child who had been captured by an enemy tribe and kept in a dimly lit cave throughout his early life; in the cave, there were only flat, grey surfaces and shadows undulating across these surfaces.

  1. When his home tribe defeated the enemy and released the now adult man from the cave, what do you think his perceptual experiences were?
  2. Did he look around the world and see it as we do, or did he “freak out” from all of the perceptual experiences that were missing in the cave?

We are all through the restrictions of our sensory systems representative to the man in the cave, in that we are tuned to only a part of the external world. Our unawareness is tuned to only a fragment of the electromagnetic frequency spectrum referred to egocentrically as the light. We do not see the entirety of the spectrum missing the infrared, ultraviolet, radio waves, microwaves, and so on. Humanity is further sensitised to sound being that we respond to and detect only sound waves in the 20,000-Hz to 200-Hz range. Olfactory senses are little better in humans. We detect a few chemicals from the atmosphere and egocentrically state that the others are odourless.

Three schools of deliberation have postulated methods in which we systematize cues from the our exterior environment to shape our interior models. The Gestalt school suggests integrated principles. These include the principles of proximity, similarity, closure, and good figure that allow us to delineate substance out of the components.

The perceptual constancy school suggests we discover that selected features of physical substance are invariant early in our being. These include size, shape, brightness, and colour which we assume as invariable to the creation and against our interior models.

Dale Purves ( postulates that an evolutionary effect has created unambiguous integrated perceptual elements derived through the quantitatively statistical property of the environment that are perfected through by learning.

Some of the substantiation representative of the notion that perception is incorporated includes an infant‘s preference “for stripes, avoidance of cliffs by animal and human babies, and single-cell recordings of visual cells”. An indication that perception is learned derives from how people rapidly adjust to inverting lenses and how the blind have difficulty with sight recovery. It would seem that humanity has integrated perceptual Hardware and programs that are required to be adjusted through practice.

Perceptual constancies: A school of perception proposing that early in life, we learn that certain properties of objects are invariant, such as size, shape, brightness, and colour.

Perceptual illusions: Situations in which our internal perceptual model of the external world is not in correspondence with reality, causing us to make mistakes in what we perceive.


  1. Coren, S., L. M. Ward, and J. T. Enns. Sensation and Perception, 6th ed. Fort Worth, TX: Harcourt Brace, 2004. A comprehensive textbook giving coverage to most topics in modern perception
  2. Dale Purves and R. Beau Lotto, Why We See What We Do: An Empirical Theory of Vision.
  3. Purves-Lab, Laboratory of Dale Purves, M.D., Center for Cognitive Neuroscience, Duke University,
  4. Visual Cognition Laboratory, University of Illinois, djs_lab/demos.html.

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