Gibsonian Approach to Direct Perception

The Gibsonian Approach to Direct Perception

There are 2 fundamentally opposing theoretical approaches to understanding perception, incorporating (1) the traditional constructivist paradigm and (2) the ecological paradigm. The constructivist perspective, proposed mainly by Helmholtz, Gregory and Rock, holds that perception is essentially a construction of the mind, and is therefore indirect. That is that in between the optical input and our perception of it, are intervening psychological processes involving mental elaboration. They believe that sensory inputs are not sufficient to mediate perception alone and that something must be added to it before the final perceptual response it achieved. Ecological theorists, on the other hand, and specifically Gibson (1950, 1966, 1979) developed a theory of direct perception that has completely rejected this scientific dogma by showing that perception was not based on sensory inputs or stimuli at all. Instead he claimed that perception was based on ecological information, which is external to the organism.

Gibsonian Approach

A. Sufficient information in a natural stimulus for it to be seen accurately. 

B. No analytical structures in the brain needed.  Visual array contains all info needed for accurate perception.

C. Laboratory perception is unlike natural perception.

Three important components of Gibson's Theory are

1. Optic Flow Patterns;

2. Invariant Features; and

3. Affordances.

1. Light and the Environment - Optic Flow Patterns

Changes in the flow of the optic array contain important information about what type of movement is taking place.

The Optic Flow pattern for a person looking out of the back of a train.

2. The Role of Invariants in Perception

We rarely see a static view of an object or scene. When we move our head and eyes or walk around our environment, things move in and out of our viewing fields. Textures expand as you approach an object and contract as you move away.

There is a pattern or structure available in such texture gradients which provides a source of information about the environment. This flow of texture is INVARIANT, according to Gibson, is an important direct cue to depth. Two good examples of invariants are texture and linear perspective.

3. Affordances

Are, in short, cues in the environment that aid perception. Important cues in the environment include:

OPTICAL ARRAY: The patterns of light that reach the eye from the environment.

RELATIVE BRIGHTNESS: Objects with brighter, clearer images are perceived as closer

TEXTURE GRADIENT: The grain of texture gets smaller as the object recedes. Gives the impression of surfaces receding into the distance.

RELATIVE SIZE: When an object moves further away from the eye the image gets smaller. Objects with smaller images are seen as more distant.

SUPERIMPOSITION: If the image of one object blocks the image of another, the first object is seen as closer.

HEIGHT IN THE VISUAL FIELD: Objects further away are generally higher in the visual field

Visual Illusions

Gibson's emphasis on DIRECT perception provides an explanation for the fast and accurate perception of the environment. However, his theory cannot explain why perceptions are sometimes inaccurate, e.g. in illusions. Neither can Gibson's theory explain naturally occurring illusions.

Gibson (1972) argued that perception is a bottom-up process, which means that sensory information is analyzed in one direction: from simple analysis of raw sensory data to ever increasing complexity of analysis through the visual system.

Information Processing Approaches

A. Based on a computer analogy

Considers stimulus input, processing in the organism, and response output.

Goal: to discover the perceptual processing necessary for perception to occur as it does.

B. In most cases, analytic, not holistic

C. The typical way in which perceptual problems are analyzed currently.

Cognitive psychology sees the individual as a processor of information, in much the same way that a computer takes in information and follows a program to produce an output.

Cognitive psychology compares the human mind to a computer, suggesting that we too are information processors and that it is possible and desirable to study the internal mental / mediational processes that lie between the stimuli (in our environment) and the response we make.

Basic Assumptions

The information processing approach is based on a number of assumptions, including:

(1) information made available by the environment is processed by a series of processing systems (e.g. attention, perception, short-term memory);

(2) these processing systems transform or alter the information in systematic ways;

(3) the aim of research is to specify the processes and structures that underlie cognitive performance;

(4) information processing in humans resembles that in computers.

The development of the computer in the 1950s and 1960s had an important influence on psychology and was, in part, responsible for the cognitive approach becoming the dominant approach in modern psychology (taking over from behaviorism).

The computer gave cognitive psychologists a metaphor, or analogy, to which they could compare human mental processing. The use of the computer as a tool for thinking how the human mind handles information is known as the computer analogy.

Essentially, a computer codes (i.e. changes) information, stores information, uses information, and produces an output (retrieves info). The idea of information processing was adopted by cognitive psychologists as a model of how human thought works.

Hence the information processing approach characterizes thinking as the environment providing input of data, which is then transformed by our senses. The information can be stored, retrieved and transformed using “mental programs”, with the results being behavioral responses.

Cognitive psychology has influenced and integrated with many other approaches and areas of study to produce, for example, social learning theory, cognitive neuropsychology and artificial intelligence (AI).