The+Controvery

= A Debate Between Theories: A Double-Crossed Objection =

It is interesting here when it comes to objections against the key findings, the key finding between two contributor to the field seem to contradict one another.

Richard Gregory
Richard Gregory proposed a theory, built of that of Immanuel Kant, called the constructivist or indirect perceptual theory. As explain previously under the Sooo How Does Perception Work tab, Richard Gregory purposed a __top-down__ indirect processing theory where he concluded that all sensory information was first interpreted by our prior experiences in order to construct meaning within our brain. He theorized that 90% of the initially sensory information was lost as it made it was from the light spectrum into our eyes, converted into a electrical signal and then sent to our brains. Because of this process our brains then inferred about the missing pieces of the puzzle.

Gregory insisted that perception could be ambiguous which was the reason for incorrect perceptions or illusion. Ambiguous perceptions also explain why we are able to perceive to completely different images within one work of art as seen on the home page of this wiki.

James Gibson
James Gibson, on the other hand, was highly critical of Gregory's theory and argued strongly against the idea that perception involves top-down processing. In fact, Gibson argues that we directly perceive stimuli without having to perform hypothesis testing as Gregory insisted (McConnell, 2009).

Gibson connected with the phrase "What you see is what you get" (McLeod, 2004). Believing that the world around us contained enough information for accurate perception, he eliminated the need for interpreting data all together.

Completely opposite of what Gregory theorized, Gibson argued that perception is a __bottom-up process__. This means that when receiving stimulus for the environment, the meaning is derived from the nature of ideas generated by the stimuli (McConnell, 2009, pg.51). In addition, he c laimed that perception is direct versus the indirect theory Gregory suggested. Concluding that perception of surfaces was more important than depth and space perception (McLeod, 2009).

Due to the fact the Gibson worked with aircraft pilots throughout World War II, he discovered "optic flow patterns" which describes the landing strip the pilot is aiming for a motionless and anything surrounding that moving. This, according to Gibson provided pilots with unambiguous sensory data about there speed, altitude and direction (McLeod, 2009).

Three important components in Gibson's theory are:



Optic Flow Patterns
Which illustrate movement relating our body to our environment. He argues that we perceived movement if optical flow was present. This can be seen in the image above as the railroad tracks appear to move away from our current location (McLeod, 2004).

Invariant Features
He purposed that features such as texture gradients produce the illusion of depth within an otherwise one dimensional image. Looking at the image to the left, the decrease of boldness on the lines creates a sense of depth (McLeod, 2004).. Gibson noted that these features do not vary from feature to feature which is why we are always able to perceive our movements.

Affordances
Afforandances is a category of visual clues including height, relative size and brightness in addition to the two mentioned above. These features aided in our perception of the environment and is why we understand our position in relation to the rest of the world at all times (McLeod, 2004; McConnell, 2009).

While Gibson strongly believed in his theory, it lacked a substantial amount of evidence explained by Gregory's theory. For example, according to Gibson illusion are only highly dramatized conditions not normally present in the real world.

A good demonstration of this is the illusion created by this red square. After continuous staring, looking elsewhere will create an image of a square even though one isn't there.