Perception of an Object!
The Perception of Figure and Ground:
The Gestalt psychologists hold that we perceive an object as a gestalt, whole, pattern or unit. We do not perceive it as an aggregate of parts as Associationists hold. As we open our eyes on a certain occasion, we have nothing before us but a green blotch on a grey background.
We perceive the blotch as a coherent whole, as a vague shape standing out from its background. We cannot take half of the green blotch along with a part of the adjacent grey as a unit. Nor can we take part of the green blotch along with distant parts of the grey, and see the combination as a unit.
The Gestalt psychologists hold that we do not have to learn to see a compact blotch as a unit, because the primary brain response to the area of homogeneous stimulation is a dynamic system and not an aggregation of separately active points.
The object of perception is always a gestalt, a whole, a configuration. It is not a mere aggregate of parts. The perception of the situation, pattern or configuration depends upon the total activity going on in the brain.
The figure is compact, and has form and outline, while the background appears like unlimited space. The figure attracts attention more readily than the ground. It stands out in bold relief. It appears to stand out towards you. The ground spreads out behind the figure.
The figure is one whole or unit. It is perceived in a background. According to the Gestalt psychologists, the distinction of figure and ground in fundamental in visual position.
We see a mountain against the background of the sky. We see a patch of colour on a wall. The patch of colour is a figure. The wall is the ground. When the baby first opens his eyes, he certainly does not see object as adults see them.
But still he may not see a mere chaos, a ‘big, booming, buzzing confusion’, as William James thought. If there is some compact bright mass of colour in his field of vision, such as a bright coloured toy, this probably stands out as a figure from the general background.
The distinction of figure and ground is not peculiar to the sense of sight. The rhythmical sound of a drum is perceived as a figure against the background of less distinct sounds. A pinch on the skin is perceived as a figure against the background of a mass of cutaneous sensations. Gestalt psychology regards the distinction of figure and ground as a fundamental principle in organising experience and behaviour.
Perception of Constancy:
(i) Size Constancy:
We have already learned that the greater the distance, the smaller the retinal or apparent size of an object, and that the shorter the distance, the larger the retinal or apparent size of it. These are the visual cues to depth perception.
But the actual experience, the size of an object remains constant whether it be at a distance of 50 feet or 100 feet upto a certain limit. When we perceive a man 50 feet away, we do not see him to be smaller, and when we perceive him 100 feet away, we do not perceive him to be bigger. We perceive him to be of the same size at both distances.
This is the perception of size constancy. If the cues to the perception of distance are present we have the perception of size constancy. We perceive an object as farther away, instead of perceiving it as smaller. But if the cues to depth perception are absent, an unfamiliar object is seen as smaller and bigger at different distances.
But the absence of the cues does not completely destroy the perception of size as known. This knowledge gives us some degree of size constancy.
(ii) Shape Constancy:
When we see a table in front of us, we perceive it to be rectangular. The object shape perceived corresponds to its retinal image. When we see it from a side, we perceive it to be rectangular, though its retinal image is trapezoid. This is called the perception of shape constancy. The knowledge of the true shape of the object eliminates the effect of the visual cues.
(iii) Colour Constancy:
When we see coal in green light, we perceive it to be black. When we see it in red light, we perceive it to be black. When we see chalk in fed light, we perceive it to be white. When we see it in blue light, we perceive it to be white. This is called the perception of colour constancy. The knowledge of the true colour of the object eliminates the effect of the light.
(iv) Brightness Constancy:
When we see coal in the bright sun, we perceive it to be black, though it reflects more light. When we see coal in the shade, we perceive it to be black, though it reflects less light. This is called the perception of brightness constancy. The knowledge of the true colour eliminates the effect of the different degrees of illumination. Perceptual constancy depends upon past experience and habits of perception.
The Perception of Time:
The perception of time is based upon the experience of duration and succession of events. We can perceive the present only. But the perceived time is not a mathematical moment but a duration or block. It is called by William James the specious present. It contains not only the present but also “an echo of the immediate past and a foretaste of the immediate future”. Actual sensation is the mark of the present time.
A hungry man is taking food; the actual sensation of the satisfaction of hunger gives him the perception of the present. The more conation is obstructed or delayed, the longer the time appears. The more it proceeds successfully and easily towards the attainment of its end, the shorter it appears. At the perceptual level the distinction between past, present and future can only be apprehended in a rudimentary way.
The ‘not yet’ consciousness contained in the prospective attitude of attention gives us perception of the future. When we anxiously wait for food, we perceive the future. The ‘no more’ consciousness gives us perception of the past.
When we have finished enjoying a sumptuous feast, we perceive the past. When conation is obstructed or delayed, the ‘not yet’ consciousness is emphasized. With the advent of memory and imagination the past and the future are distinctly apprehended. We have memory of the past and expectation and imagination of the future. Stout accounts for the perception of time—past, present and future in this manner.
William James speaks of the physiological sense of time. Bridges stresses the importance of “physiological rhythms, tensions and relaxations within the organism” in the perception of time. J. F. Dashiell also suggests that there are physiological cues to the perception of time, the nature of which has not yet been exactly determined by experiments.
Some “qualitative changes in organic conditions” or “qualitative summation” of the rhythms of respiration, heartbeat, digestion, phasic changes in striped muscles, and chemical processes in the body may be the cues to the perception of time.
Some people have the wonderful power to tell the precise hour, in the day time or at night, without calculation. They have physiological sense of time. Boring, Langfeld and Weld also regards “the rhythms of pulse and breathing, digestion,” and the like as fundamental to the perception of time.
The Gestalt psychologists reject this analytical approach to the problem of the perception of time and maintain that the brain has the innate power of perceiving time as a “whole’, a pattern. The brain perceives motion as four-dimensional, time being its fourth dimension. The process of perception is a temporal process, time being its fourth dimension.
The Perception of Space or Extension—Space means extension, and consists of two factors, material and formal. The plurality of co-existent, resisting points constitute its material factor. The order and arrangement among them constitute its formal factor.
We perceive extension through the cooperation of three factors; (1) extensity, local signs, and (2) movement. The extensity of visual or tactual sensations gives us a presentation of a plurality of co-existing, resisting points together. Local signs of visual or tactual sensations inform us that they are different from one another.
Through active movement we perceive the order and arrangement among the different resisting points co-existing with one another. The movement converts extensity into extension. The extensity of tactual and visual sensations, local signs and motor sensations in cooperation yield the perception of space.