Discuss Gregory’s Top Down Theory of Perceptual Organisation (8 + 16 marks)
Richard Gregory’s 1974 theory of Top Down Processing suggests that perception is an active, constructive process in which both perceptual/sensory input from the environment and previous knowledge interact to produce our perception. Unlike Gibson, Gregory is not reductionist, and stresses the importance of other factors, such as previous knowledge and expectations in accurate perception, rather than just sensory input and ‘affordances’. Sensory input alone, according to Gregory, is insufficient for accurate perception.
The case study of SB – a man who had been blind for the entire 52 years of his life can support Gregory’s assumption of the importance of previous knowledge in perception. SB could tell the time by using the touch vision he learned in childhood, which supports the role of previous experience and learning in accurate perception. While this can be criticized for being un-generalisable due to being a case study, it had a massive importance on Gregory’s theory, which still is one of the most influential theories explaining perceptual organisation today, and can be supported by experimental studies into previous knowledge.
Gregory’s suggestion that we combine sensory information and previous knowledge to form a hypothesis about what we perceive has been supported by Khorasani et al (2007). In this study, the Muller Lyer illusion (which automatically adjusts the apparent size of a more distant object so the second line looks longer) had less of an impact on participants once they knew it was an illusion. This supports Gregory’s claim that previous knowledge (i.e. being told that what they are experiencing is an illusion) can change the way a person perceives something, suggesting the importance of previous knowledge in hypothesis formation. In addition, the Charlie Chaplin