Perception Theory The issue of perception in various fields, including philosophy and psychology has been debated with vigor over the last fifty years. In fact, a large amount of experimental work has been completed regarding questions such as the object of perception, the relationship between perception and though, and the nature of perception representational.

In general it is believed that perception occurs without apparent effort. What is seen is imposed upon the brain and perception is the natural consequence. Theorists have however argued that this is not the case. There are a number of factors involved in the perception process. These factors influence the way that objects are perceived. It has for example been argued that perception is a process of information transmission and elaboration. The cognitivist paradigm holds that a flow of information in the mind, similar to computer software, influences the way that objects are perceived.

The lines of thought related to visual perception can be divided into the top-down approach, which is concept-driven, and the bottom-up approach, which is direct, and also related to Gibson's view. The concept-driven approach assumes several information processes within the mind while perception is taking place. Light intensities on the retina are for example assumed to be transformed on the retina in order to perceive the environment. Theories adhering to this principle are known as the constructivist approach. The assumption inherent in the constructivist approach is that several events intervene between stimulation of the perception organs and experience. Inferential processes play a role in forming the internal hypotheses, expectations and knowledge inherent in the final experience related to the vision process. Furthermore inherent factors such as motivation and emotion are important to the outcome of the process.

There are many shortcomings to this approach. Contrary to the prediction that perception is likely to be in error fairly often, studies have shown it to be accurate.

Artificial and unnatural stimuli have been used in experiments and demonstrations, rendering these invalid. It appears that the more contemporary approaches to visual perception may therefore offer more in terms of validity.

In order to consider the theory of perception then, Gibson's ecological approach and Marr's computational theory are discussed below. The computational theory appears to oppose the environmental theory in its paradigm that the mind mediates all that is perceived. What is perceived is then influenced by processes in the mind in order to give a message of perception to the brain. This is compared with Gibson's direct approach to vision.

J.J. Gibson and the Ecological Approach to Vision

Gibson studied under vision philosophers such as Koffka, while also being influenced by Lewin and Piaget to arrive at his ecological view. He is popularly believed to have coined the term "affordence," and is the founder of the concept of Ecological Perception. The ecological approach suggests a more direct theory.

According to this approach, there is no mediation from the mind between the object of perception and the perception event itself. The function of perception is thus one of adaptation. The purpose of perception is then to adapt the organism to its environment. Gibson's approach is therefore born of the assumption that information within the environment itself, and not in the brain, is sufficient for an organism to move around and interact with the environment. Information is provided by the environment through the direct perception process itself. Organization of action occurs by means of the information derived from the physical environment itself, while action and movement play a role in accurate perception.

The main problem with most theories of visual perception, according to Gibson, is that the phenomenon is considered from a static, abstract perspective. He suggests a more dynamic approach to rectify what he sees as the essential misconception of the perception process. Instead of static, the individual is a moving point in the landscape, or visual array. The environment's layout as it relates to possibilities for action and perception is then seen in terms of its invariant structure. Gibson assumes that all the visual information emanating from the environment is included in the light pattern reaching the retina. The visual or optical array is therefore supposed to provide unambiguous data regarding what is observed. This information occurs by means of texture gradients, optic floe patterns and affordances. The information is in no way influenced by intermediate information processing.

Furthermore Gibson concentrates not on how form itself is perceived, but rather on invariants detected by the visual system. Vision relies on invariants in the dynamic optical array. The...

The invariants are then also those of the physical object outside the mind, rather than the images projected on the retina. Gibson referred to the study of these invariants as the Ecological Optic. This is applicable to Gibson's theory on the perception of light. Light cannot actually be seen, but is seen only by means of illuminated objects. These appear as variations in the environment and are thus able to be seen.
Gibson's ecological geometry system describes a world directly perceived by the observer, without any intervention from the faculties of the mind. This perceived world is accurate only to what is directly perceived, and not to any idealism of science such as mathematics. He however does not argue that such mathematically precise distinctions are not possible in a description of the world. Instead the focus is on the spontaneous, unconscious perception of the world, where such concepts are not used.

Thus there is a distinction between the physical properties of the environment in scientific terms, and the way in which the individual experiences the environment. Gibson questions the validity of imposing physical explanations for the world on a description of the world as it appears to its perceiver. Thus Gibson's argument focuses on a misconception of the visual process, rather than erroneous conclusions as a result of this. He attempts to understand the world through perception as it occurs, rather than through perception as it is imposed upon by learning, thought, or any other mediating processes in the brain.

According to Gibson, therefore, development in any visually active organism, from birth to maturity, is a process of distinguishing the physical features of the world around it. It is thus seen as a learning process through which a seeing person begins to distinguish what is outside of the body, as opposed to a process within the mind by which perception is influenced. The influence of perception thus emerges from the environment outside the seeing person, rather than from the mind.

Perception is then, according to Gibson, a process of clarification which is influenced by evolution. The way in which the perception organs develop influences the way that things are seen. This is also influenced by what is necessary for the survival of a particular organism. Things that are perceived through the senses are specified by way of the light, sound and odor connected with them. Gibson negates all previous and subjective memories as influence on perception. Perception is influenced directly by the environment alone.

Gibson expands his theory in relation to 3-dimensional objects. The movement of the perceiver plays a role here. According to this theory, 3D forms are not perceived through outline with an added form through shading and other such visual cues. Instead they are perceived by the various transformations and relations that shapes undergo as the perceiver moves. This is connected with the view that each eye represents a field of vision. The environment with its potential points of vision are then perceived through both fields of vision to form a 3D image of the environment through which the perceiver moves.

Affordances are explained as the potential use of objects. These, by being perceived directly, provide meaning to the environment. According to Gibson this is also a feature inherent in the evolution process. More than one affordance can be attributed to an object according to the perceiver's species and psychological state. This furthermore substantiates the close connection between perception and action.

Meaning according to Gibson is thus located in physical interaction between organism and environment rather than in the mind alone. Thus information available from the environment relates directly to the meaning derived from perception. It follows that information is energy flowing continuously within the environment and thus from the environment to the physical perception organs of the perceiver. Rather than therefore imposing information upon the environment through the perception process, the function of the brain is to seek information by means of the perception organs and their orientation.

Gibson's theories have proved sound for a number of reasons. In terms of philosophy, Gibson's view brought a new focus to the environment as central to the human experience.

When coupled with motion, his contentions regarding the richness of stimuli were shown to be correct. Furthermore his view that inaccurate perception is often the result of artificial situations has also proved accurate. None of the constructivist approaches have proved Gibson's theories incorrect, and in turn Gibson has revealed a number of constructivist fallacies.

There are however also shortcomings to…