Discuss Gregory’s theory of perception

Gregory’s theory of perception consists of a proposal which suggests that formation of incorrect hypotheses will lead to errors in perception. Perception involves making inferences about what we perceive through prior knowledge, past experiences, sensory data and internal hypotheses which play a major part in explaining perception. Gregory adds that an individual’s external and internal factors are determined by expectations, emotion and motives, and so enables two separate individual’s to perception of the same object differently. For example if a hungry person is observing a picture of a dinner table with a bowl of fruit on it, the observer may focus more upon the fruit than other details within the picture. However, Gregory goes on to explain that these factors which can affect perception sometimes cause people to have a wrong perception of an object, predicting that once the perceptual information reaches the eyes 90% is lost by the time it reaches the brain. This occurs due to information being lost through the visual system, as well as the brain letting go of any unnecessary information.
Gregory used the Hollow-Face illusion (also known as Hollow-Mask illusion) as an example of an optical illusion to explain how expectations can affect how we perceive objects. In this case how the observer perceives a concave mask of a face which appears as a normal convex face. While a convex face will appear to look in a single direction, and a flat face which can appear to follow the moving viewer, a hollow face can appear to move its eyes faster than the viewer: looking forward when the viewer is directly ahead, but looking at an extreme angle when the viewer is only at a moderate angle. According to Richard Gregory this illusion shows the strong visual bias for the participants favouring to see a hollow mask as a normal convex face. This is a key example of how perception can act as a top-down process for visual knowledge. This bias of seeing faces as convex which the