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AFTER inner perception, outer perception! The next three chapters will treat of the processes by which we cognize at all times the present world of space and the material things which it contains. And first, of the process called Sensation.
SENSATION AND PERCEPTION DISTINGUISHED.
The words Sensation and Perception do not carry very definitely discriminated meanings in popular speech, and in Psychology also their meanings run into each other. Both of them name processes in which we cognize an objective world; both (under normal conditions) need the stimulation of incoming nerves ere they can occur; Perception always involves Sensation as a portion of itself; and Sensation in turn never takes place in adult life without Perception also being there. They are therefore names for different cognitive functions, not for different sorts of mental fact. The nearer the object cognized comes to being a simple quality like 'hot,' 'cold,' 'red,' 'noise,' 'pain,' apprehended irrelatively to other things, the more the state of mind approaches pure sensation. The fuller of relations the object is, on the contrary; the more it is something classed, located, measured, compared, assigned to a function, etc., etc.; the more unreservedly do we call the state of mind a perception, and the relatively smaller is the part in it which sensation plays.
Sensation, then, so long as we take the analytic point of view, differs from Perception only in the extreme simplicity of its object or content. Its function is that of mere acquaintance with a fact. Perception's function, on the other hand, is knowledge about a fact; and this knowledge admits of numberless degrees of complication. But in both sensation and perception we perceive the fact as an immediately present outward reality, and this makes them differ from 'thought' and 'conception,' whose objects do not appear present in this immediate physical way. From the physiological point of view both sensations and perceptions differ from 'thoughts' (in the narrower sense of the word) in the fact that nerve-currents coming in from the periphery are involved in their production. In perception these nerve-currents arouse voluminous associative or reproductive processes in the cortex; but when sensation occurs alone, or with a minimum of perception, the accompanying reproductive processes are at a minimum too.
I shall in this chapter discuss some general questions more especially relative to Sensation. In a later chapter perception will take its turn. I shall entirely pass by the classification and natural history of our special 'sense-tions,' such matters finding their proper place, and being sufficiently well treated, in all the physiological books.
THE COGNITIVE FUNCTION OF SENSATION.
A pure sensation is an abstraction; and when we adults talk of our sensations' we mean one of two things: either certain objects, namely simple qualities or attributes like hard, hot, pain; or else those of our thoughts in which acquaintance with these objects is least combined with knowledge about the relations of them to other things. As we can only think or talk about the relations of objects with which we have acquaintance already, we are forced to postulate a function in our thought whereby we first become aware of the bare immediate natures by which our several objects are distinguished. This function is sensation. And just as logicians always point out the distinction between substantive terms of discourse and relations found to obtain between them, so psychologists, as a rule, are ready to admit this function, of the vision of the terms or matters meant, as something distinct from the knowledge about them and of their relations inter se. Thought with the former function is sensational, with the latter, intellectual. Our earliest thoughts are almost exclusively sensational. They merely give us a set of thats, or its, of subjects of discourse, with their relations not brought out. The first time we see light, in Condillac's phrase we are it rather rather than see it. But all our later optical knowledge is about what this experience gives. And though we were struck blind from that first moment, our scholarship in the subject would lack no essential feature so long as our memory remained. In training-institutions for the blind they teach the pupils as much about light as in ordinary schools. Reflection, refraction, the spectrum, the ether-theory, etc., are all studied. But the best taught born-blind pupil of such an establishment yet lacks a knowledge which the least instructed seeing baby has. They can never show him what light is in its 'first intention'; and the loss of that sensible knowledge no book-learning can replace. All this is so obvious that we usually find sensation 'postulated' as an element of experience, even by those philosophers who are least inclined to make much of its importance, or to pay respect to the knowledge which it brings.
But the trouble is that most, if not all, of those who admit it, admit it as a fractional part of the thought, in the old-fashioned atomistic sense which we have so often criticised.
Take the pain called toothache for example. Again and again we feel it and greet it as the same real item in the universe. We must therefore, it is supposed, have a distinct pocket for it in our mind into which it and nothing else will fit. This pocket, when filled, is the sensation of toothache ; and must be either filled or half-filled whenever and under whatever form toothache is present to our thought, and whether much or little of the rest of the mind be filled at the same time. Thereupon of course comes up the paradox and mystery: If the knowledge of toothache be pent up in this separate mental pocket, how can it be known cum alio or brought into one view with anything else? This pocket knows nothing else; no other part of the mind knows toothache. The knowing of toothache cum alio must be a miracle. And the miracle must have an Agent. And the Agent must be a Subject or Ego ' out of time,'—and all the rest of it, as we saw in Chapter X. And then begins the well-worn round of recrimination between the sensationalists and the spiritualists, from which we are saved by our determination from the outset to accept the psychological point of view, and to admit knowledge whether of simple toothaches or of philosophic systems as an ultimate fact. There are realities and there are ' states of mind,' and the latter know the former; and it is just as wonderful for a state of mind to be a ' sensation' and know a simple pain as for it to be a thought and know a system of related things. But there is no reason to suppose that when different states of mind know different things about the same toothache, they do so by virtue of their all containing faintly or vividly the original pain. Quite the reverse. The by-gone sensation of my gout was painful, as Reid somewhere says; the thought of the same gout as by-gone is pleasant, and in no respect resembles the earlier mental state.
Sensations, then, first make us acquainted with innumerable things, and then are replaced by thoughts which know the same things in altogether other ways. And Locke's main doctrine remains eternally true, however hazy some of his language may have been, that " though there be a great number of considerations wherein things may be compared one with another, and so a multitude of relations; yet they all terminate in, and are concerned about, those simple ideas either of sensation or reflection, which I think to be the whole materials of all our knowledge.... The simple ideas we receive from sensation and reflection are the boundaries of our thoughts ; beyond which, the mind whatever efforts it would make, is not able to advance one jot ; nor can it make any discoveries when it would pry into the nature and hidden causes of those ideas."
The nature and hidden causes of ideas will never be unravelled till the nexus between the brain and consciousness is cleared up. All we can say now is that sensations are first things in the way of consciousness. Before conceptions can come, sensations must have come; but before sensations come, no psychic fact need have existed, a nerve-current is enough. If the nerve-current be not given, nothing else will take its place. To quote the good Locke again:
"It is not in the power of the most exalted wit or enlarged understanding, by any quickness or variety of thoughts, to invent or frame one new simple idea [i.e. sensation] in the mind.... I would have any one try to fancy any taste which had never affected his palate, or frame the idea of a scent he had never smelt ; and when he can do this, I will also conclude that a blind man hath ideas of colors, and a deaf man true distinct notions of sounds."
The brain is so made that all currents in it run one way. Consciousness of some sort goes with all the currents, but it is only when new currents are entering that it has the sensational tang. And it is only then that consciousness directly encounters (to use a word of Mr. Bradley's) a reality outside itself.
The difference between such encounter and all conceptual knowledge is very great. A blind man may know all about the sky's blueness, and I may know all about your toothache, conceptually ; tracing their causes from primeval chaos, and their consequences to the crack of doom. But so long as he has not felt the blueness, nor I the toothache, our knowledge, wide as it is, of these realities, will be hollow and inadequate. Somebody must feel blueness, somebody must have toothache, to make human knowledge of these matters real. Conceptual systems which neither began nor left off in sensations would be like bridges without piers. Systems about fact must plunge themselves into sensation as bridges plunge their piers into the rock. Sensations are the stable rock, the terminus a quo and the teminus ad quem of thought. To find such termini is our aim with all our theories—to conceive first when and where a certain sensation may be had, and then to have it. Finding it stops discussion. Failure to find it kills the false conceit of knowledge. Only when you deduce a possible sensation for me from your theory, and give it to me when and where the theory requires, do I begin to be sure that your thought has anything to do with truth.
Pure sensations can only be realized in the earliest days of life. They are all but impossible to adults with memories and stores of associations acquired. Prior to all impressions on sense-organs the brain is plunged in deep sleep and consciousness is practically non-existent. Even the first weeks after birth are passed in almost unbroken sleep by human infants. It takes a strong message from the sense-organs to break this slumber. In a new-born brain this gives rise to an absolutely pure sensation. But the experience leaves its 'unimaginable touch' on the matter of the convolutions, and the next impression which a sense-organ transmits produces a cerebral reaction in which the awakened vestige of the last impression plays its part. Another sort of feeling and a higher grade of cognition are the consequence; and the complication goes on increasing till the end of life, no two successive impressions falling on an identical brain, and no two successive thoughts being exactly the same. (See above, p. 230 ff.)
The first sensation which an infant gets is for him the Universe. And the Universe which he later comes to know is nothing but an amplification and an implication of that first simple germ which, by accretion on the one hand and intussusception on the other, has grown so big and complex and articulate that its first estate is unrememberable. In his dumb awakening to the consciousness of something there, a mere this as yet (or something for which even the term this would perhaps be too discriminative, and the intellectual acknowledgment of which would be better expressed by the bare interjection 'lo!'), the infant encounters an object in which (though it be given in a pure sensation) all the ' categories of the understanding' are contained. It has objectivity, unity, substantiality, causality, in the full sense in which any later object or system of objects has these things. Here the young knower meets and greets his world; and the miracle of knowledge bursts forth, as Voltaire says, as much in the infant's lowest sensation as in the higliest achievement of a Newton's brain. The physiological condition of this first sensible experience is probably nerve-currents coming in from many peripheral organs at once. Later, the one confused Fact which these currents cause to appear is perceived to be many facts, and to contain many qualities. For as the currents vary, and the brain-paths are moulded by them, other thoughts with other 'objects' come, and the 'same thing' which was apprehended as a present this soon figures as a past that, about which many unsuspected things have come to light. The principles of this development have been laid down already in Chapters XII and XIII, and nothing more need here be added to that account.
Excerpted from The Principles of Psychology by William James. Copyright © 1918 Alice H. James. Excerpted by permission of Dover Publications, Inc..
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CHAPTER XVIII. IMAGINATION
Our images are usually vague
Vague images not necessarily general notions
Individuals differ in imagination ; Galton's researches
The 'visile' type
The 'audile' type
The 'motile' type
The neural process of imagination
Its relations to that of sensation
CHAPTER XIX. THE PERCEPTION OF 'THINGS'
Perception and sensation
Perception is of definite and probable things
"Illusions;-of the first type, -of the second type"
"The neural process in perception, 'Apperception'"
Is perception an uncouscious inference?
The neural process in hallucination
CHAPTER XX. THE PERCEPTION OF SPACE
The feeling of crude extensity
The perception of spatial order
The meaning of localization
The construction of 'real' space
The subdivision of the original sense-spaces
The sensation of motion over surfaces
The measurement of the sense-spaces by each other
Feelings of movement in joints
Feelings of muscular contraction
Summary so far
How the blind perceive space
Helmholtz and Reid on the test of a sensation
The theory of identical points
The theory of projection
"Ambiguity of retinal impressions,-of eye-movements"
The choice of the visual reality
Sensations which we ignore
Sensations which seem suppressed
Discussion of Wundt's and Helmholtz's reasons for denying that retinal sensations are of extension
CHAPTER XXI. THE PERCEPTION OF REALITY
Belief and its opposites
The various orders of reality
The sense of our own bodily existence is the nucleus of all reality
The paramount reality of sensations
The influence of emotion and active impulse on belief
Belief in theories
Relations of belief and will
CHAPTER XXII. REASONING
"In reasoning, we pick out essential qualities"
What is meant by a mode of conceiving
What is involved in the existence of general propositions
The two factors of reasoning
The part played by association by similarity
The intellectual contrast between brute and man: association by similarity the fundamental human distinction
Different orders of human genius
CHAPTER XXIII. THE PRODUCTION OF MOVEMENT
The diffusive wave
Every sensation produces reflex effects on the whole organism
CHAPTER XXIV. INSTINCT
Instincts not always blind or invariable
Two principles of non-uniformity in instincts:
1) Their inhibition by habits
2) Their transitoriness
Man has more instincts than any other mammal
The hunting instinct
Sociability and shyness
CHAPTER XXV. THE EMOTIONS
Instinctive reaction and emotional expression shade imperceptibly into each other
The expression of grief; of fear; of hatred
"Emotion is a consequence, not the cause, of the bodily expression"
Difficulty of testing this view
Objections to it discussed
The subtler emotions
No special brain-centres for emotion
Emotional differences between individuals
The genesis of the various emotions
CHAPTER XXVI. WILL
Voluntary movements: they presuppose a memory of involuntary movements
No need to assume feelings of innervation
The 'mental cue' for a movement may be an image of its visual or auditory effects as well as an image of the way it feels
Ideo motor action
Action after deliberation
Five types of decision
The feeling of effort
Unhealthiness of will:
1) The explosive type
2) The obstructed type
Pleasure and pain are not othe only springs of action
All consciousness is impulsive
What we will depends on what idea dominates in our mind
The idea's outward effects follow from the cerebral machinery
Effort of attention to a naturally repugnant idea is the essential feature of willing
The free-will controversy
"Psychology, as a science, can safely postulate determinism, even if free-will be true"
The education of the Will
CHAPTER XXVII. HYPNOTISM
Modes of operating and susceptibility
Theories about the hypnotic state
The symptoms of the trance
CHAPTER XXVIII. NECESSARY TRUTHS AND THE EFFECTS OF EXPERIENCE
Programme of the chapter
Elementary feelings are innate
The question refers to their combinations
What is meant by 'experience'
Spencer on ancestral experience
Two ways in which new cerebral structure arises: the 'back-door' and the 'front-door' way
The genesis of the natural sciences
Scientific conceptions arise as accidental variations
The genesis of the pure sciences
Series of evenly increasing terms
The principle of mediate comparison
That of skipped intermediaries
Our doctrine is the same as Locke's
Relations of ideas v. couplings of things
The natural sciences are inward ideal schemes with which the order of nature proves congruent
Metaphysical principles are properly only postulates
Æsthetic and moral principles are quite incongruent with the order of nature
Summary of what precedes
The origin of instincts
Insufficiency of proof for the transmission to the next generation of acquired habits
Posted January 28, 2013
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