Edward B. Titchener defined perception “as a group of sensations to which meaning is added from past experiences.” In contemporary psychology, perception is commonly treated as an intervening variable dependent upon stimulus factor, earning sets, moods, and emotional and motivational conditions of the organism.

Thus, perception refers to assigning meaning to an object or objective event arising out of the stimulus conditions and organismic factors. Perception of the same thing by different persons is different because each individual perceives in terms of those aspects of the situation that have significance for him. The following statement is an operational definition of perception. Perception is a cognitive mechanism of sorting out, interpretation, analysis, and integration of stimuli involving our sense organs and brain.

Though perception represents a step beyond sensation, it is difficult to locate a precise boundary between the two. When the brain receives the sensory information, it automatically interprets those. Some psychologists prefer to call the dual process of sensation and perception as a unified information processing system or the perceptual system. Perception is a receptive, selective, symbolic, and affective process.

1. Perception is a receptive process:


Sensation provides the raw materials for perception. Through sensation, we come in contact with various objects and events around us. Our sense organs are called the receptor organs, which help us to receive stimulations from our environment. Those stimulations are carried on to the central nervous system, where they are interpreted using our past knowledge, and we perceive the object or event. We cannot perceive without having a sensation. Recently, instead of treating sensation and perception as completely separate processes, psychologists prefer to talk about a perceptual system. Perceptual system includes both sensation and perception. Sensation, which is basically a receptor process, forms a part of the perceptual system. Hence, perception is regarded as a receptor process.

We have several sense organs or receptor organs. Some of them, such as the eyes, ears, nose, skin, and the tongue help us to receive stimulations from the outside world. On the other hand, the kinesthetic, organic, and vestibular organs help us to receive stimulation from the internal body conditions. We have different types of sensations and perceptions, each of which arises from the stimulation of different sense organs. We have visual sensation and perception if our eyes are stimulated; we have auditory sensation and perception if our ears are stimulated; and have kinesthetic sensation and perception, if our kinesthetic muscles are stimulated.

However, in all these cases, the receptor organs must receive sensory information, which must be passed on to the appropriate center of the brain for processing. A visual stimulation, for example, is received by the visual receptor cells of the eyes and then transmitted to the primary visual context of the occipital lobe for processing.

Thus, the visual perceptual system includes the visual receptor cells of the eyes and the primary visual cortex of the occipital lobe. Similarly, the auditory perceptual system includes the auditory receptor cells of the ears and the primary auditory cortex of the temporal lobe. The same principle holds true for all other perceptual systems.


2. Perception is a selective process:

Perception begins with the stimulation of the sense organs and is carried out through its interaction with psychological factors like learning, motivation, interest, beliefs, set, and attitude of the individual. At any given point in time, our sense organs are influenced by hundreds of stimuli from the outside world. But in fact, we don’t perceive all those stimuli. We select a particular stimulus or only a few of them for further processing. This process of selecting a stimulus or a group of stimuli from among a large pool of stimuli is called attention. Our sense organs may be activated by a stimulus, but if we do not attend to it, we cannot perceive the stimulus.

Therefore, attention is a basic and primary process essential to our perception. It works as a sensory filter by selecting some part of the sensory input for further processing. Broadbent conceived of attention as a selective filter that deals with the overwhelming flow of incoming sensory information by blocking out the unwanted sensory input and passing out the desired input. Therefore, attention is called the selective part of the perceptual process, or pre-perceptive attitude.

The involvement of attention in perception can be learnt from the following example. While you are inside the class, you may seem to be carefully listening to the lecture, which you may not be really doing. Your sense organs are in tact; your teacher is very much present in front of you; he is delivering the lessons in a very loud voice. But you do not understand what he is saying (perceive) probably because you are not attending to him. Instead, you are attending to something else, such as what your friends are doing outside the class, or what else you must do after the class is over, and so on. Thus, in the above example, it is noted that attention is a basic requirement of perception.


The following experiment also provides evidence of how attention is a necessary component of the perceptual process. Hernandez Pion (1956) conducted an experiment with a cat. He directly stimulated the auditory receptor cells of the cat by sending sound waves into the ear through an electrode. When the stimulation reached the temporal lobe, he measured the electrical vibration of the temporal lobe by electroencephalogram (EEG).

In the EEG record, he observed that the cat perceived the sound waves. As stimulation of the auditory receptor cells was continuing, Pion placed a rat in front of the cat. Interestingly, electrical vibrations from the temporal lobe were immediately cut off. Instead, electrical vibrations were observed in the occipital lobe. He explained that the rat was a more desired object for the cat than the sound.

Therefore, when the two stimulations were simultaneously presented to the cat, he attended to the preferred stimulus. As a result, perception of sound discontinued and vibration in the temporal lobe stopped. EEG vibrations were recorded in the occipital lobe because the cat visually attended to the rat.

In the above experiment, it is observed that even if an intense stimulation is received by any of our sense organs, it cannot be perceived unless it is attended to. Hence, attention is a basic part of our perceptual process, which helps us to select stimuli from among a large number of stimuli that influence our sense organs. An important nature of the attention process is that it always changes or shifts its focus from one sensory impulse to another unless it is deliberately held steady. Two types of factors cause shifting of attention: (i) the stimulus factors, and (ii) the subjective factors.


The stimulus factors are called the objective factors, which are associated with the object or the event to which the individual is attending. Some of the important stimulus factors are stimulus intensity, contrast, size, novelty, color, stimulus change, and so on. In fact, advertisers capitalize on these stimulus factors to catch the attention of the consumers.

The subjective factors of attention are the characteristics of the person who attends to the object or the event. Important subjective factors of attention are motives, interests, beliefs and attitude, set and expectancy and so on. For example, if you are hungry, you will be attracted to food. You do not expect anything good in your enemy; therefore, you will attend to his bad qualities more often than his good qualities.

2. Perception is a symbolic process:

Symbol is a substitute for some object or event. That perception is a symbolic process means that while carrying out the perceptual activity, we do not use the object or event in its actual form but use some symbols representing the object or the event. The symbols used in perception are called images.


In other words, an image is a cognitive product, which takes the place of an object or event in our mental processes. Hence, the mental picture is the image, which is a symbol for the actual object.

For example, if you are asked to draw the picture of a mango, you can draw it. How is this possible for you when you do not see the mango right then? You can draw it because you have seen the mango earlier and have formed an image of it. The image of the mango is a symbol for the real mango. Now, as you see a real mango, sensation or stimulation generated by the presence of the mango reaches the brain. Brain interprets the sensory stimulation in terms of your previous experiences with mango which have been stored there as images or symbols. All these activities take place simultaneously to help you know about the mango, and thereby your perception of mango is complete. These activities during your perception show that perception is a symbolic process.

3. Perception is an affective process:

It means that each act of our perception is associated with a pleasant or unpleasant feeling, and a liking or disliking toward the object or the event of perception. While you perceive the mango, you may remember the color, shape, taste, and place of availability of similar types of mangoes that you might have seen in the past. Thus, you may like or dislike the mango as you come to know about it in terms of your experiences with those types of mangoes. Sometimes, perception is also associated with strong emotional consequences to the perceiver. For example, as you see a snake in the field, you tremble with fear. When you see your enemy, you shiver with anger. All these examples point to the fact that the person experiences some sort of affection associated with each act of his perception. This affective state may be pleasant or unpleasant. There is a great deal of individual differences with regard to the affection associated with perception. In fact, the affective processes account for individual differences in the perception of the same object.