Whilst part of what we perceive comes through our senses from the object before us, another part (and it may be the larger part) always comes out of our own mind.” (James, 1890). With regard to your coverage of perception in this module, outline the ideas and thinking behind this statement. In most dictionaries perception is more or less described as “the process by which an organism detects and interprets information from the external world by means of the sensory receptors” (Collins English Dictionary, 2012). However in psychology, we appreciate that perception also employs previous knowledge to interpret each of the stimuli registered by the senses: We see perception as being the inner process which allows us to experience the world around us and make sense of it. In this essay I will outline some of the theories behind our understanding of perception today; their differences and shortcomings and the role prior experience and learning plays in our interaction with our environment.
Over the last forty years, our understanding of sensation and perception has made huge strides with the advent of the computer age, which has given researchers a relevant analogy and vocabulary to describe the internal processes for the first time; also with the development of brain-scanning techniques, we can use fMRI and Pet scans to help us confirm what once was only supposition. But it is thanks to theories put forward by earlier psychologists, such as Helmholtz (Richards, Joan, L., 1977) and the Gestaltists (Banerjee, J. C., 1994, p 107-108) that neuropsychologists can narrow their research to focus on the areas identified by their predecessors - as being most relevant - to understanding perception, cognition and behaviour.
William James held a world view in line with pragmatism, declaring in Principles of Psychology (1890) that the value of any truth was utterly dependent upon its use to the person who held it. His contention that “Whilst part of what we perceive comes through our senses from the object before us, another part always comes out of our own mind” underlines the subjective nature of the world outside of ourselves and how it exists only as it is perceived by each person. Immanuel Kant, whose most direct influence, can be seen in Gestalt psychology, put it more succinctly when he said: “We perceive things not as they are but as we are” (1785).
Sensation is the means by which we receive information about our environment through our five senses, touch, taste, sound, sight and smell (though notable US neuroscientist, Paul-Bach-Y-Rita (1998) would argue that balance is also one) and perception is how we interpret these sensations: Rays of light are collected by the eye and focussed on the retina and travel via the optic nerve to the primary visual cortex, which is the part of the brain that interprets the image (McLeod, S. A. 2007). Most psychologists agree that perception, is not just the passive recipient of these stimuli but, calls upon past experiences and previous knowledge make them more meaningful to us, i.e., an items use or its speed. The question is however, how do we interpret external stimuli and in what format do we internalise these images or movements in the brain to enable us to instantly identify, store and recall them when needed. Psychologists are also divided on - to what extent perception relies directly on the information present in the stimulus?
Some theories, outlined below, support William James’ notion of ‘no one truth’ and postulate that perceptual processes are not direct, but depend on the perceiver's expectations and previous knowledge (top-down) as well as the information available in the stimulus itself (bottom-up), while others don’t.
One of the first theories on this subject was by Hermann Von Helmholtz ((Richards, Joan. L. 1977, pp. 235-253), who augmented his reasoning with detailed knowledge of the anatomy of the sensory...