Module 14: Perceptual Interpretation (pp. 181-189)

Use the player below to listen to the audio recording of this lecture.

Perceptual Adaptation

In this module, we will look at the role of experience and learning in our perceptions.  Scientists and Psychologists have looked at people who were born blind and therefore taught by touch and sound to see and how their visual systems work after sight has been restored (many were born with cataracts that were later corrected with surgery).  While these individuals were able to see color, distinguish figure from ground, and some other perceptual abilities, they often could not recognize by sight objects that were familiar by touch. Their eyes didn't degenerate, but the lack of visual stimulation caused the cells to not develop normal connections.  This again shows how experience guides, sustains, and maintains the brain's neural organization and points to the existence of a critical period shortly after birth (an optimal time when certain events must take place) for normal sensory and perceptual development. 

In vision, the ability to adjust to an artificially displaced or even inverted visual field is known as Perceptual Adaptation.  When we get a new pair of glasses, we may feel slightly dizzy or disoriented but we adjust within a day or two.  Imagine if you were given a pair of glasses that shifted the view of objects 40 degrees to the left, would you be able to adapt to this distorted world?  The answer is yes; within a few minutes, your throws/handshakes/etc. would be accurate.  But then once you took the glasses off, you would have an after effect where you error in the opposite direction (again you would adapt in a few minutes).  What if you had glasses that turned the world upside down?  Again, you can still adapt though it may take longer longer.  It isn't that your visual system and brain make this new view normal, but more that we adapt to context and learn to coordinate our movements.

Perceptual Set.jpg As discussed above, you can see the role of our experiences in vision and perception.  We are heavily influenced by our experiences, assumptions, and expectations when perceiving the world.  This can be further evidenced through what is called a Perceptual Set or a mental predisposition to perceive one thing and not another.  We often perceive what we expect to perceive.  When you look at the images to the left, do you see clouds or flying saucers? A log in the water or the Loch ness monster? We are heavily influenced by context.  Imagine hearing a noise interrupted by the words "eel is on the wagon".  You would likely perceive the first word as wheel.  Given "eel is on the orange" you would likely hear peel.  This shows how the brain can often work backward in time to allow a later stimulus to determine how we perceive an earlier one.

Class Experiment

As discussed above, we have a critical period for sensory and perceptual development. Related to this conclusion, Psychologists have observed that our senses and brain need variety in incoming stimuli. Click "Play" on the video below for an introduction and description of this optional class experiment!

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