Peception Involves Bottom and Top Down Processing

Topics: Visual system, Perception, Sense Pages: 6 (2003 words) Published: October 7, 2012
Evaluate the evidence that visual perception involves bottom-up and top-down processing.

The perceptual system is comprised of a of a diverse range of senses including visual, auditory, olfactory and tactition; the perceptual system is part of the nervous system, which contains millions of nerve cells called receptors that sense and respond to a plethora of sensory stimuli including light, sound and temperature. The act of perceiving rather than merely sensing enables us to analyse and make sense of incoming sensory information, allowing us to construct a description of the environment to inform and guide our actions within a complex, dynamic world. For primates, as compared to other species, vision has predominantly been relied upon to guide interaction within the environment and as such has evolved to become more highly developed and sophisticated than the other senses (Pike & Edgar, 2010 p.66); consequently, how visual perception arises, the goal of perception and the processes involved are debated and disputed within the psychological field. This essay shall evaluate evidence put forward by ecological, constructive, and dual-process approaches in light of whether they posit visual perception as involving bottom-up and /or top-down processing.

Technologic advances afford us a clear understanding of the physiology of sight; incoming light permeates the cornea, which is focused into the retina containing receptor cells called rods and cones. Rods assist vision in low-level light, whilst cones, located primarily in the fovea are responsible for detecting fine detail and colours. The rods and cones are linked to the optic nerve, which send information via the lateral geniculate to the visual cortex. The visual cortex is responsible for processing the incoming visual information (Pike & Edgar, 2010 pp 66 & 94); how this information is then interpreted is what we term perception. Whilst science can implicitly explicate the visual system, visual perception is individual and thus subjective and susceptible to alteration; inferences about the processes involved in visual perception are therefore derived from theory, research and experiments. Ideas put forward about the processes involved are influenced by whether the primary goal of perception is considered to be action or recognition, and whether the direction information is seen as flowing up or down through perceptual system.

As we engage with the environment, information is received via the senses; in visual perception, light arrives at the retina and is subsequently processed via the visual system whereby a description of the world is generated to form an interpretation of what is being perceived. This process is termed Bottom-up as perception is achieved from sensory data flowing up through the perceptual system. This sensory data cannot however merely enter and exit the perceptual system; once sensory information is analysed and a description of the environment is formed, the internal representation of what is being sensed must be stored so as the memory of that experience can inform and guide subsequent interactions with the environment. Utilizing stored knowledge to aid

interpretation of future interactions with visual stimuli is referred to as top-down processing (Pike & Edgar pp.68-69). These concepts suggest that perception can arise through bottom-up or top-down processes; whilst one may assume that it is an interaction of these processes that result in perception, some approaches advocate that only a singular process is necessary to formulate perception.

One such advocate is J.J Gibson (1950, 1966) whom proposes that the principle goal of perception is action. Gibson puts forward that to achieve action it is not necessary for sensory information to endure complex cognitive processing; rather action arises as a result of the perceptual system’s active engagement with a dynamic, visually rich environment, containing sufficient information to lead to...
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