CHAPTER VI.
Perception.
IT is a common mistake that we perceive everything that is reported to the mind by the senses. As a matter of fact we perceive but a very small portion of the reports of the senses. There are thousands of sights reported by our eyes, sounds reported by our ears, smells reported by our nostrils, and contacts reported by our nerves of touch, every day of our lives, but which are not perceived or observed by the mind. We perceive and observe only when the attention, reflex or voluntary, is directed to the report of the senses, and when the mind interprets the report. While perception depends upon the reports of the senses for its raw material, it depends entirely upon the application of the mind for its complete manifestation.
The student usually experiences great difficulty in distinguishing between sensation and perception. A sensation is a simple report of the senses, which is received in consciousness. Perception is the thought arising from the feeling of the sensation. Perception usually combines several sensations into one thought or percept. By sensation the mind feels; by perception it knows that it feels, and recognizes the object causing the sensation. Sensation merely brings a report from outside objects, while perception identifies the report with the object which caused it. Perception interprets the reports of sensation. Sensation reports a flash of light from above; perception interprets the light as starlight, or moonlight, or sunlight, or as the flash of a meteor. Sensation reports a sharp, pricking, painful contact; perception interprets it as the prick of a pin. Sensation reports a red spot on a green background; perception interprets it as a berry on a bush.
Moreover, while we may perceive a simple single sensation, our perceptions are usually of a group of sensations. Perception is usually employed in grouping sensations and identifying them with the object or objects causing them. In its identification it draws upon whatever memory of past experiences the mind may possess. Memory, imagination, feeling, and thought are called into play, to some extent, in every clear perception. The infant has but feeble perception, but as it gains experience it begins to manifest perceptions and form percepts. Sensations resemble the letters of the alphabet, and perception the forming of words and sentences from the letters. Thus c, a, and t symbolize sensations, while the word "cat," formed from them, symbolizes the perception of the object.
It is held that all knowledge begins with sensation; that the mental history of the race or individual begins with its first sensation. But, while this is admitted, it must be remembered that sensation simply provides the simple, elementary, raw material of thought. The first process of actual thought, or knowledge, begins with perception. From our percepts all of our higher concepts and ideas are formed. Perception depends upon association of the sensation with other sensations previously experienced; it is based upon experience. The greater the experience, the greater is the possibility of perception, all else being equal.
When perception begins, the mind loses sight of the sensation in itself, for it identifies it as a quality of the thing producing it. The sensation of light is thought of as a quality of the star; the pricking sensation is thought of as a quality of the pin or chestnut bur; the sensation of odor is thought of as a quality of the rose. In the case of the rose, the several sensations of sight, touch, and smell, in their impression of the qualities of color, shape, softness, and perfume, are grouped together in the percept of the complete object of the flower.
A percept is "that which is perceived; the object of the act of perception." The percept, of course, is a mental state corresponding with its outside object. It is a combination of several sensations which are regarded as the qualities of the outside object, to which are combined the memories of past experiences, ideas, feelings, and thoughts. A percept, then, while the simplest form of thought, is seen to be a mental state. The formation of a percept consists of three gradual stages, viz.: (1) The attention forms definite conscious sensations from indefinite nervous reports; (2) the mind interprets these definite conscious sensations and attributes them to the outside object causing them; (3) the related sensations are grouped together, their unity perceived, and they are regarded as qualities of the outside object.
The plain distinction between a sensation and a percept may be fixed in the mind by remembering the following: A sensation is a feeling; a percept is a simple thought identifying one or more sensations. A sensation is merely the conscious recognition of an excitation of a nerve end; a percept results from a distinct mental process regarding the sensation.