in this way, slowly and laboriously, a large number •inside; of sensations will be set up in skin and muscle, joint and tendon. These sensations are aroused, as a matter of fact, in active attention. Blended together, they make up the experience of ejfort which always Effort. accompanies this form of attention. A conscious- ness in the state of active attention thus differs from consciousnesses in the state of passive and secondary passive attention in that a new concrete process, the experience of effort, is introduced into it, over and above the exaltation and depression of ideas already present.
That the bodily attitude of attention *will out,' even under circumstances when it would be well that it should not, is seen from the following passage in Fenimore Cooper's Last of the Mohicans: " But Heyward saw that while to a less instructed eye the Mohican chief appeared to slumber, his nostrils were expanded^ his head was turjied a little to one side^ as if to assist the organs of hearing, and that his quick and rapid glances ran incessantly over every object within the power of his vision" (ch. xix.).
§ 35- Apperception. — Our nervous tendencies, in- herited and acquired, decide what we shall attend to, or (in other words) decide when we shall feel. Each man picks out a world of his own from the great world around him, and is affected by the events of this private world; and the nature of the little world in which he lives his individual life is determined by perception 86 Attention his mental constitution. Let us see what this means in a particular instance. Selective Suppose that you are opening a new number of a magazine, or the daily paper. As you do so, your eye is * caught ' by some word in the column before you: say, by the word grapnel. Every one who reads much has probably had this experience of the ' catching ' of the eye by some word on the newly turned page. As a rule, however, we go on to our reading, and do not think anything about the matter. Yet it is, to the psychologist, a matter of great interest, as a very little consideration will show.
(i) Our eye has been caught by the word grapnel. Turning to the place where we saw it, we may find that the word is really there. The paragraph tells of a shipwreck or some other nautical event, and the term ' grapnel ' is used by the writer. In this case we have seen the letters just as they are printed.
Even here, however, our tendencies have been at work. For the word ' grapnel ' is not printed more clearly, in blacker ink or larger letters, than the other words of the paragraph. We should not have seen it, and failed to see them, unless we had been biassed, unless the idea of * grapnel ' had somehow fitted in with our mental constitution.
(2) But the word need not be there. Looking carefully down the column we may find nothing nearer to * grapnel ' than the word grape: the para- graph is discussing the grape harvest. Then we say: *' I must have seen ' grape ' and thought of 'grapnel/ because I was so interested last night (or last week or last month) in that article on anchors. I had anchors in my mind, though I didn't know it when I opened the paper."
(3) But, again, the word 'grape' need not be there. There may be no word in the whole para- graph that is at all like * grapnel '; no word beginning with gr. Then we should say: '* That's curious! I must have been so full of the anchor article that I saw 'grapnel' in my imagination and supposed I saw it on the paper. I shall be more careful next time."
(4) And lastly: not only may there be no word like ' grapnel ' in the column, but there may have been no article on anchors read lately. Rack our memory as we will, we may be wholly unable to find any reason for our having seen that particular word. Then we should say: ''That's very curious! Of course, I have always been interested in ships; but why I should have seen 'grapnel' just now, when I wasn't thinking of ships or anything to do with them, passes my comprehension."
.The psychologist will offer a similar explanation and its of these three facts. In (2) and (3), he will say, the ^^p^"^^°"' reading of the article on anchors had thrown open certain channels of tendency, the tendency that makes you 'interested in ships.' So you read what is before you not as it really is, but as you see it with your mind turned into these channels (^. §§ 10, 12). You were biassed or prejudiced before you opened the paper. As for the last case, the ship-tendencies were so strong there that no opening of flood-gates was needed. Your mind is set so strongly in one direction that you are likely to see everything through 88 Attention shipping-spectacles. You do not realise that you are biassed: it seems ^natural ' to you that ships should be interesting. But it is just because the love of ships is ingrained in your nervous system that your perception in this case is a perception of some- thing which is not there, — that you have interpreted a certain arrangement of black marks which do not read * grapnel ' as if they spelled that word. Appercep- All these four cases are cases of what is called ^^°"* apperception. An apperception is a perception whose character is determined, not by the nature of the thing perceived, but by the peculiar tendencies of a nervous system. Sometimes, as in cases (2) and (3), you can tell by introspection how the channels of tendency have been opened up (by the reading of the article on anchors); sometimes, however, the ten- dencies are so strong in themselves, and date so far back beyond the limits-of your memory, that, while you see their effects (the alteration of perception), you cannot tell what it is that takes your mind in their direction on any particular occasion. And again: while som.etimes the tendencies assist per- ception, as in case (i), at other times they may lead you badly astray in your interpretation of the outside world, as in the three remaining instances.
§ 36. The Working of Attention. — The experimental study of attention has given us valuable knowledge as to the way in which the mind works in the atten- tive state. Two points may be mentioned here. The duration (i) We Cannot attend to the same thing for any a ention. j^^g^-]^ q£ \\vcvq. together. The attention-wave rises § 36. Tlie Working of Attention 89 and falls at short intervals: attention fluctuates. The longest stretch of attention recorded is a stretch of 24 sec, and the average length of attention is no more than 5 or 6 sees. Often- times, of course, we seem to be steadily attending for a long period to some one thing (as when we are reading a book, or listening to music); but in reality the topic is continually changing, and the drops and spurts of attention are not noticed as we pass from idea to idea, or from phrase to phrase.
A favourite amusement at country fairs is that of shooting at an egg-shell which dances up and down upon a jet of water. The pressure of the water is variable, so that you never know when the ^gg will drop and when it will spring up. — You may think of the attention-wave in Fig. 10 as a jet of this kind, and of the idea attended to as the egg-shell. Every half-dozen sec- onds the jet spurts up, and the idea becomes clear; but the spurt is followed by a drop, in which the idea falls into obscurity again.
(2) We cannot attend to many things at once. If The range a page of Sprinter's pie,' a page of letters mixed at ^ attention. haphazard, is shown to us for a second or two, we can read only 4 or 5 letters in a single flash of atten- tion. The top of the attention-wave cannot carry more than 4 or 5 simple perceptions at the same time. But — and this is the important thing — we can read 4 or 5 familiar short words as easily as we can read the 4 or 5 separate letters. This shows that our reading of short words is done by general impression, by a grasp of the look of the whole word rather than by any method of spelling-out the letters.
It would be impossible for us to read as quickly as we do if we read by letters. If I am reading a work on the fauna go Atte7ition of x^ustralia, and the word orjiithorhyncus occurs, I probably see the first two or three letters distmctly, then have a vague impression of a long line of high and low letters, and then catch the final cics as my eye moves towards the right-hand side of the page. With my Australia- tendencies at work, this is fully enough to give me the meaning of the whole word ornithorhyncus.
Again: if we read by letters, we should not be so apt as we are to overlook misprints in books. As we read so largely by general impression, a wrong letter here or there does not matter, — does not attract the attention.
§ 37. The Physiological Conditions of Attention. — To understand the physiological conditions of atten- tion, we must understand the general plan upon which the nervous system is built. Thestructu- Think of the nerves which run from the sensenervous sys- orgaus to the bram as a number 01 railway-lmes.
tern These lines converge at first in the lower braincentres, the grey masses within the brain (/^, 752). Running farther, they converge again in the various sense-areas of the brain-cortex {F., 768). Running still farther, the lines end in a single terminus, the cortex of the frontal lobes (Wundt, Outlines of Psy- chology, pp. 205, 206). From all three sets of stations — from the lower centres, the sense-areas and the frontal terminus — other lines run out to the muscles.
and its The use of the lower centres we shall discuss attTnTion. °^ later (§§ 72, 106). We are now concerned with the sense-areas and the terminus. Attention to an idea probably means, on the physiological side, that the running lines to and fro between the terminus and the sense-area in which that idea is excited are open, Qicestions and Exercises 91 while the Hnes to and from other sense-areas are blocked. When an explosion of cells in the visual area is reinforced by an explosion of cells in the frontal lobes, the thing seen is attended to.
When a cell has exploded, it must take time to recover; it cannot explode again till it has been re- charged. That is why attention is interrupted, why we can attend only for a few seconds at a time. The spurts of the attention-wave correspond to the succes- sive discharges of cortical cells..
If this account of the bodily conditions of attention be correct, it is clear that affection, too, will not appear in consciousness unless the frontal lobes are excited (§ 33). And there is good reason to think that the tilt of the body for good or harm is reflected in the state of the frontal lobes. If they are well nourished, irrigated by abundant fresh blood, the thing attended to is pleasant; if they are ill-nourished, it is unpleasant.
Questions and Exercises (i) Give a list of the things which in your own experience appeal to the passive attention, and of the things which always require an effort if they are to be attended to. Can you draw from your experience any instance of secondary passive atten- tion? If so, trace its development from active attention.
(2) Write out all the words you can think of which are de- scriptive of mental constitution.
(3) What incidents can you remember, in history or in fic- tion, which bring out differences of mental constitution?
(4) Describe carefully the bodily attitude {a) of the scout (visual attention) and {b) of the eavesdropper (auditory atten- tion). What sensations are set up by the two attitudes? What is the reason for the difference between the two?
(5) Prove the fact that the attention is interrupted, not con- 92 Attention tinuous, in this way. Seat the subject bhndfold in a chair, so that he sits sidewise to the length of the room. Hold a watch at the level of his ear, and remove it until its ticking is only just audible. As he listens, the sound will alternately disappear and reappear: disappear as the attention-wave falls, and reappear as it rises again. Let him lift his finger at each disappearance. Count off on the watch the number of seconds between disap- pearance and disappearance.
(6) Make an outline sketch of the nervous system, showing the ingoing and outgoing nerves, the two sets of stations and the frontal terminus. Mark the two kinds of nerves in different- coloured inks. With the sketch in your hand, and without look- ing at the book, tell just what happens in the nervous system (a) when we are attending to a pleasant sight and (^) when we are attending to an unpleasant sound.
(7) If unpleasant feelings are bad for us, why should we be attracted by unpleasant topics? Why should we be ^fascinated' by accounts of brutal murders and distressing accidents?
(8) If a child has fallen and hurt itself, and you can distract its attention from the pain, it stops crying. Why is this?
(9) To test the range of attention, i.e.^ to find out how many objects can be attended to at once, you must have a simple appa- ratus constructed. Fasten two stout uprights, 4 ft. high, upon a base. The inner surfaces of the uprights must be grooved, so that a board i ft. wide will slide down easily between them. The uprights may be braced together behind. Make the sliding board 3 ft. long. At its centre cut out a lo-inch square. It is well to paint board and uprights black. Six inches from one end of the board, and directly in the middle, tack a round piece of white card, of i in. diameter. ' ^ Cut pieces of stout cardboard i ft. square. Over 10 square inches of the cards paste (a) large black letters in haphazard order, and (p) sets of short words. Four words of four letters should fill the 10 inches. For each experiment pin one of these cards to the back of the uprights, with its upper edge just i ft. below their top.
Raise the sliding board, so that its bottom is level with the bottom of the card attached to the uprights. The card is now covered by the board; and the round white mark on the board lies over the centre of the group of words or letters. Tell your audience to look at this mark; and drop the board. The 10- Questions and Exercises 93 inch opening falls over the 10 -inch group of letters, letting them be seen for a moment; and the board comes to rest with its upper portion covering the card again. To prevent noise, lay a strip of felt between the feet of the uprights. And if the onlookers have (as will probably be the case) followed the falling mark with their eyes, instead of looking steadily at the place that it fell from, repeat the experiment with the same card. Let each member of the audience write down what letters or words he sees as the board drops.
By driving a wire-nail through one of the braces of the uprights and letting the point penetrate the back of the sliding board you can hold the latter in position till the audience is ready for an experiment. Then release it by withdrawing the nail.
(10) It is said above that a performing animal (a trained dog or monkey) gives evidence of secondary passive attention. Explain this.
(11) Why is it that the hidden drawing in a ^puzzle picture^ is so difficult to see at first, and so difficult not to see when you have once found it?
(12) Can you give any reason, besides that mentioned in § 12, for the occurrence of blanks in your introspection of the idea of References James, Textbook^ ch. xiii. (Perform the experiments indicated Sully, Hii7nan Mind, vol. I., pp. 74-79? ^h- ^i- Titchener, Outline, §§ 35-42. Wundt, Lectures, Lects. XVI., XVII. Wundt, Outlines, §15.
CHAPTER VI How sensa- tions are put together.
Perception § 38. The Formation of Perceptions and Ideas. — Most people, if asked what were the simplest bits of mental experience, of mind, that they could namiC would say: ''Perceptions, and feelings, and ideas." They would look upon sensations, if they thought of them at all, as physical processes (§ 27), and they would not dream of separating affection from the perceptions and ideas that it accompanies.
We saw in § 28 how easily the feehngs might be taken for simple, elementary processes. It is natural that the same mistake should be made in the case of perceptions and ideas: for these, with the feelings, are the simplest processes that occur in real life, in everyday mental experience. Recalling the terms used in § 8 we may say that they are the simplest concrete processes in rriind, — the simplest that we can find by ordinary observa- tion, without employing the scientific method of introspection.
Feeling we have already discussed (§ 25). And we have more than once referred to perceptions and ideas as 'groups of sensations.' How, now, are these concrete processes formed } How is it that certain sensations get welded or blended together so closely that the whole looks, at first sight, like one simple process } If we make our question more definite, it will fur- nish its own answer. Why does my idea of Lake Cayuga include sensations of blue and cold^ and not sensations of sour and strain? The reason is clear.
94 § 39- Difference betwee^i Perception and Idea 95 Sensations hold together in consciousness when the stimuH, the things or processes in the outside world that give rise to them, occur together. Natural objects appeal to the mind, in each of their aspects, through some particular sense-organ: every object, as a whole, appealing to several sense-organs. The sensations hold together, then, just as the different aspects of the natural object hold together. The perception or idea stands for, represents, means some material thing or process; and the sensations that compose it can no more fall apart than the blue- ness of the water can be separated in my experience from its coolness.
Sensations are welded together, therefore, under the influ- The bidding ence or at the bidding of our physical surroundings. A per- o^"^^^^^- ception or idea always means something, stands for some object. Mind is developed in close interaction with nature; and what nature binds together remains together in percep- tion and idea.
§ 39. The Difference between Perception and Idea. — Perception Perceptions and ideas are, both alike, groups of sen- j^deaTnter- Sations; and, both alike, groups of sensations which ^^^^y aroused.
are held together by the command of nature. They differ solely in this respect: that, when we perceive, the object which arouses the sensations is actually be- fore us, appealing to various sense-organs; whereas, when we have an idea, the object is not before us, but the sensations are set up inside the brain without any disturbance of the organs on the surface of the body.
Sensations may be set up from outside the body, by Instances of stimulation of eye or ear or nose; or they may be set up ^nd^Idea^^ from within the body, by an excitation in the cortical area 96 Perception to which the nerves from eye or ear or nose run (§§ 14, 16). This excitation may be aroused directly, by a change in the blood-supply of the cortical area; or indirectly, by an im- pulse running to this area from other cells which have been exploded by a stimulus working at the outside of the body. Thus I may see a green tree in my mind's eye when there is before me neither any green object nor anything to sug- gest green: in this case the green-cells have been exploded by a change in blood-supply. Or I may see it because I am reading a description of scenery in which the printed word ' green ' occurs: in this case the green-cells are exploded indirectly, by way of the word stimulus. A per- ' ception, then, contains sensations of the first kind, those set up from outside the body; an idea consists wholly of sensa- tions of the second kind, those aroused directly or indirectly within the brain itself. When I am looking at a table, as it stands in front of me, I have a perception of a table, I per- ceive it; but if I shut my eyes and think of a table, or if some particular table ^ comes into my head' along with other memories, or if I am picturing to myself the sort of table I mean to buy when I am rich enough to furnish my study properly, then I have an idea of a table, I ideate it.
Introspective This difference, however, is most certainly a differ- ence that makes itself known to introspection. We can all tell a perception from an idea. Sometimes, it is true, we make laughable mistakes by confusing the two: but only a drunkard or a madman would habitually confound real things with remembered or imagined things. What, then, is the introspective difference between the two groups of sensations t the idea is In the first placc, (i) the sensations differ greatly m strength or mtensity m the two cases. My per- ception of a table is much more vivid, much more of a living reality, than my idea of it is. Ideas are pale § 39- Difference between Perception and Idea 97 and faint, compared with perceptions. Again, (2) the sensations that make up the idea are less lasting than those of the perception. Of course, the percep- tion (just because it is mental) is 2. process^ a going on: as I look at the table the centre of interest changes, the attention travels from sensation to sensa- tion; I cannot hold the whole sensation-group fixed and steady, as if it were a thing. But the idea is still less stable less stable, still more fluid; the sensations that make it up come and go with even greater swiftness. And lastly, (3) the idea is less perfect, a less accurate pict- and less ure of the outside world, than the perception. Look tlhan^the at the view from your window. Now shut your eyes, perception. and form an idea of the view. The space has shrunk, so to speak; details are lost; you are not sure about this and that feature of the landscape. Or try to form an idea of the happenings of five minutes. It is hardly possible: the time seems to have shrunk, as the space did in the previous example. —These are the three differences that introspection reveals be- tween perception and idea, between a sensation-group containing outside elements and a sensation-group made up entirely of elements from within the brain.
The reason for the differences is this. When we perceive, Reason for the sensations are held fast, and constantly renewed, by their *^^^^ differ- Stimuli. The details of the landscape, the events of the ^v^ minutes, are there to catch the eye and ear. But when we are merely thinking of something, there are no outside stimuli to attach our thought to, to refresh ourselves by; it requires a greater effort to attend, and there is a crowd of rival ideas hovering round the central idea and ready to dis- place it. So the idea is weaker, more changeable and less complete than the perception.
H 98 Perception The outside world is a world of quality, of space and of time.
All three aspects are practically important.
Since the differences between the inside and the outside sensa- tions are so great, some physiologists hold that their excitations occur in different parts of the brain-cortex. Thus a sensation of sight due to the action of light upon the eye would be set up by the explosion of cells at the back of the head. But if that sensa- tion were recalled in memory, when no stimulus was present, it would be set up in an area of the cortex lying midway between this sight-area and the frontal terminus. There w^ould thus be four sets of stations in the nervous system {cf. § 37): lower centres, sense-areas, areas of centrally aroused sensations, frontal lobes. The matter is still in dispute, and will doubtless remain so for some time to come. (See Donaldson, Growth of Brain, 266.)
§ 40. The Three Classes of Perceptions. — There are three aspects of things that strike us, as we look out upon the world around us. (i) In the first place, we are struck by the likenesses and differences among things. Everything is itself, and not something else; and at the same time, everything is more like certain things than it is like certain other things. (2) Sec- ondly, we are struck by the arrangement of things in space. One thing is here, another there; one is far off, another close at hand; one is large, another small; one of this form, another of that. And lastly, (3) we are struck by the progress of things in /^'m^. The thunder follows the lightning; a bird flies ^ across the landscape now slowly and now quickly; the waves beat upon the shore with a defi- nite rhythm; the shooting stars drop irregularly, in quick succession or at long intervals.
All these aspects of things are of great practical impor- tance to us: otherwise, indeed, they would never have ' struck ' us at all. Think of the importance of the first aspect for the merchant! He must know good cloth from bad, good sugar from bad, good timber from bad; else we shall not go to him to supply us with food and clothes and M § 40. The Th^ee Classes of Perceptions 99 shelter. Again, we must know how far off things are, and where they are, and how large they 'will prove to be when we get to them; else navigation and the planning of towns and the building of houses would be impossible. Lastly, we must know when things happen, and how long they take, and how often they occur; else we could not travel, — could not even lay out a single day's work.
Each of these three aspects of material things gives rise to its own set of perceptions; and each set of perceptions is built up upon a particular attribute or aspect of sensations, (i) Perceptions of the first Wehave kind may be termed perceptions of quality or quali- ^^^ ^ ^ ^^^' tative perceptions; they tell us of the nature or quality of things. These perceptions are built up of sensations looked at as qualities (§ 22), without regard to their intensity, etc. (2) Perceptions of the second spatial kind are termed perceptions of space, or spatial per- ceptions. They are built up of sensations looked at as surfaces or extents^ not as qualities or intensities. (3) Perceptions of the third kind are perceptions of and tempo- time or temporal perceptions, and are built up of [^n^^^^^^' sensations looked at as lengths of time, or durations^ not as qualities, intensities or extents.. ^^ We are already familiar with the idea that sensations have quality and, besides quality, a certain amount of strength or intensity. The fact that they have extent and duration is something that we have not hitherto touched on.
Take duration first. Think of any sensation that occurs to you: a red, a sweet, a pressure, a strain, a tone, a scent. Can you think, of it as lasting no time? No! However short it is, it must last for a moment. And this character of lasting a Httle while, of having duration, — a character which belongs to all sensations, from whatever organ they 3 lOO Perception come, — is what makes it possible for them to combine in such a way as to form time-perceptions.
Extent is rather more difficult. We are accustomed to regard extent as a mark of material things, of solid bodies; and it seems strange to say that mental processes have it. But think of a colour. Can you think of it in any other way than as a patch of colour, a spread-out colour? How- ever small you make it in your thought, however much you reduce it to a point of colour, has it not still length and breadth? So with pressure on the skin. Think of a press- ure which is as point-Hke as you can conceive it, the pressure of a fine needle. Still it is spread out; you could measure the length and breadth of the needle-point under the micro- scope: and you cannot form an idea of pressure at all except as having some length and breadth, some extent.
This character of extent belongs only to sensations of sight and to the sensations of pressure coming from skin and joint. But these sensations never appear in conscious- ness without it; and through it we get our perceptions of space. — No other sensations possess it: not even sensations of taste or temperature, still less those of sound and smell. It is curious to think, but it is true, that we should not know the world to be a space-world if we had no sensations of colour or brightness or pressure.
Instances of Most important of our qualitative perceptions are percepion. -j-j^Qg^ of colour (mixture of brightness and pure colour), of a ^ note ' or chord in music, of taste and smell, and of touch (mixture of skin sensations with those coming from muscle, tendon and joint). Among spatial perceptions we may mention those of place or position, of form, of size, of distance, of direction, of extent of movement; and among temporal percep- tions, those of place or position in time, of rhythm, of frequency, and of rate of movement. Each of these perceptions has its own psychological history, its own § 41- The Developme7it of Perception loi mode of formation. We must be content here to touch very briefly upon a few of the most valuable.