After reading this article you will learn about:- 1. Meaning and Definition of Perception 2. How we Perceive? 3. Sensation and Perception 4. Organisation 5. Factors 6. Perceptual Disorders.
Meaning and Definition of Perception:
Perception is the act of interpreting a stimulus generated in the brain by one or more sense mechanism.
i. “All the processes involved in creating meaningful patterns out of a jumble of sensory impressions fall under the general category of perception”—Charles Jorris.
ii. “Perception is the organizing process by which we interpret our sensory input”—Edmund Fantino.
iii. “Perception is the first event in the chain which leads from the stimulus to action”—Boring EG.
Thus perception is a highly individualized process that helps an organism, in organizing and interpreting a complex pattern of sensory stimulation for giving them the necessary meaning to initiate his behavioural responses. Thus it is concerned with the task of organizing full patterns or whole.
How we Perceive?
Ordinarily, we are not aware of the processes that determines our perception. Whether they are perceptions of sight, hearing or touch, we rarely stop to analyze the incoming sensations and the basis of our interpretation.
We know only that we see, hear and respond to situations in meaningful contexts. This is the characteristic human approach to anything that is familiar in the environment, we are accustomed to organizing things in our mind into a form, shape, melody or scene that makes up our mind a meaningful whole, whatever the perception, it is a unified experience.
Sensation and Perception:
Sensation is concerned with the initial contact between organisms and their physical environment. Perception is identifying the process through which we interpret and organize sensory information to produce our conscious experience of objects and objects relationship.
Sensation is defined as a process whereby stimulation of receptor cells send nerve impulses to the brain, where they register as a touch, sound, taste, splash of colour and so forth. Our behaviour depends on how we understand and interpret stimuli from the world around us. So the cause of behaviour may be due to both sensation and perception.
The main difference between sensation and perception is that, sensation receives and sow secondary stimulus from the external world, while perception interprets, analyses and integrates the stimulus with other secondary information.
Organization of Perception:
Gestalt followers point out causes of certain natural tendencies which might be related to organizing and grouping of perception in the brain. These are the tendencies which might be related to learning or experience.
These patterning tendencies have been classified descriptively as factors of:
1. Principle of similarity
2. Principle of proximity
3. Principle of continuity
4. Principle of closure.
1. Principle of similarity:
Items of the same size, shape or quality are more likely to be reviewed as a group or pattern than similar elements.
Here there is a strong tendency to see four alternating groups of double rows because of our inclination to units. For example, the similar X’s and O’s even though the rows are evenly spaced.
x x x x o o o o x x x x o o o o x x x x o o o o
x x x x o o o o x x x x o o o o x x x x o o o o
By reason of this same organizing tendency, when we view a land, sea or any one travelling over a large city in an aero plane cannot help but pick out the clusters of similar houses here and there which represent recent building development.
2. Principle of proximity:
Items that are closed together tend to be grouped in our perceptions.
Example: dis abl est ish
Here we see 4 groups of three letters each even though they are meaningless in this form, we see them as dis/abl/est/ish in different. However, as we were to bring them close together you would no longer see 4 groups, but rather the one equally meaningless word ‘disablestish’.
3. Principle of continuity:
In viewing a pattern such as shown below two factors are prevalent, we see the dots as straight line and not as separate dots. Further the dots are grouping themselves as two continuing lines rather than as 4 short lines meeting at central focus.
This is called the factor of continuity and illustrates our natural opposition to break the continuous flow of line, pattern or design in our perceptual awareness.
If we look at the geometrical shapes which are given below, we actually see them as a triangle, square and circle. Although they are not complete, if we see them carefully, but still there exist strong inclination to perceive them as unified wholes, thus we tend to fill mentally fill or “close” them.
5. Principle of continuation:
Anything which extends itself into space in the same shape, size and colour without a break is perceived as a whole figure.
6. Principle of simplicity:
According to this Gestalt’s principle, we tend to interpret our sensory stimulation in a way that we perceive the simplest possible pattern. The ‘simplicity’ or ‘configurational goodness’ of a figure is said to observe the general rule that the information about the parts is able to provide knowledge of the whole.
7. Principle of contour:
A contour refers to a boundary between a figure and its ground. The degree of the quality of this contour separating figure from ground is responsible for enabling us to organize stimuli or objects into meaningful patterns.
8. Principle of context:
Perception is context-dependent, that is the setting in which a perceived stimulus or object appears. For example, a word or phrase would be perceived differently in different contexts.
9. Principle of contrast:
Perception is affected through contrast effects as the stimuli that are in sharp contrast to nearby stimuli may draw our maximum attention and carry different perceptual effects. For example, the surrounding circles in (i) in the figure below make the central circle seems larger than the central circle in (ii), even though the two are of the same size.
10. Principle of adaptability:
The perception of stimuli may also depend on the adaptability of the perceiver. For example, a person working in very intensely- lit surroundings daily may perceive normal sunlight as somewhat dim, while someone working in a darkroom may perceive sunlight as very bright. Thus, there is an organizing tendency to complete and incomplete pattern.
Factors Influencing Perception:
(a) Perceptual Constancy:
Refers to the tendency to perceive the stimuli present in our input as relatively stable and unchanging even though in reality there may be attention in sensory information with reference to the shape, size, colour, brightness or other characteristics.
It is possible on account of our previous experience, knowledge and familiarity with a particular sensory stimuli, we tend to have a stable, regular and consistent perception of that particular stimulus despite the significant change introduced in terms of sensory impression. There are a number of different types of perceptual constancy like shape constancy, size constancy, colour constancy, brightness constancy or loudness constancy, etc.
(b) Perception of Space:
It involves the problems of three dimensional perception. In visual perception of space, an object in the environment is to be perceived in terms of three relationships to the viewer, i.e. the height (up-down), the width and the distance or depth (near- far).
The retina on which all our visual images are to be projected is flat. It has only two dimensions, the height and width, but it has no perception depth of a object which helps effectively in the distance and depth (near and far).
The retina on which all our visual images are projected is a flat surface, but it will be managed by some specific visual aids that help us to respond accurately to the direction, distance and depth of a perceived object. The cues that help effectively in the distance and depth perception are divided into two classes as monocular cues and binocular cues.
Visual monocular cues are those that have been derived from vision with one eye, i.e. they are effective even if one of the eyes is closed. In contrast to visual monocular cues, binocular cues require the vision with both eyes.
(c) Perception of Distance:
The one or two important monocular cues of distance are known by sound reference to loudness and echolocation. Loudness of the sound provides clues for the judgment of the distance of an object. Loudness of sound gives clues for nearby object, whereas a weak and soft sound stands for relatively distant objects.
In echolocation, we are supposed to judge the distance of an object by emitting sounds and then taking note of the time taken for the return of the echo’s. This is similar to that of a radar system, another example which can be taken in the organisms like bats and dolphins make use of these phenomena to understand its surroundings.
(d) Perception of Direction:
The cues with regard to the direction of the sound sources are provided with the binocular cues like time difference and intensity different cues. The time difference cues help us to judge the right direction of sound forces.
Since our ears are located on the left and right sides of our head, a sound wave coming from either side is bound to reach one of the ears before it reaches the other. This time difference proves to be a sufficient base for accurate estimation of the direction of sound sources, particularly of medium and low frequency tones.
The intensity difference cues prove helpful in locating the direction of the high frequency tones. The difference in the intensity of sound reaching the two ears is referred to as intensity difference.
This difference is because of the fact that sound waves coming from the left or right side of one listener have to bend his head to reach the farther ear. Thus the far away ear receives a less intense sound in comparison to the other ear which is very closer to the source of sound.
Such intensity differences help us in providing and judging the direction of the sound source. This way the joint efforts of monocular and binocular cues help us to great extent to localize sounds in space, in terms of distance as well as direction.
(e) Perceptual Illusions:
It represents gross mis-judgement or false perception. The sensory information received by our sensory receptors is interpreted and given some meaning to the process of perception, sometimes this interpretation goes wrong and resulting perception fails to correspond with reality. Such false perceptions are gross misinterpretation of the sensory information and are called perceptual illusions.
The following are a few types of illusion:
1. Illusion of size
2. Illusion of length
3. Illusion of perception
4. Illusion of curvature
5. Illusion of horizontal-vertical
6. Illusion of movement.
Mainly, there are two types:
False perceptions are called illusions. When we perceive something and mistake it for something that is not really there, it is a case of illusion. For example, a toy apple may be mistaken for a real apple.
Perceptual illusions are of different types.
The major ones are:
1. Illusion of size:
For example, a child may perceive a football as larger in size than what an adult would perceive the same object. This change in perception arises due to change in the frame of reference.
2. Illusion of length:
Although both the lines below are identical, yet the bottom one is perceived as longer. This is the famous Muller-Lyer illusion. This is caused by our interpretation of angles at the ends of the lines as perspective cues.
3. The horizontal-vertical illusions:
In the figure below, though the two lines are of equal length, the vertical one is perceived as the longer one, mainly due to our field of vision.
4. Illusions of movement:
Often, we perceive movement of objects we are looking at, even though they are actually not moving. An easy example is the illusion of movement of a bus/train, when the one in which we are sitting is actually moving.
Hallucinations are imaginary perceptions. They are an extreme form of inaccurate observation in which one sees or hears something that is not seen or heard by others around him. For example, a drunkard may see pink elephants, etc. Usually, hallucinations appear most frequently in the life of mentally disordered persons.