Another question on the economical management of memorizing: Is it

better to keep steadily going through the lesson till you have it, or

to go through it at intervals? If you were allowed a certain time, and

no more, in which to prepare for examination on a certain memory

lesson, how could the study time be best distributed? This question

also has received a very definite answer.

{342}

Spaced repetitions are more effective than unspaced. In an experiment

of Piéron, a practised subject went through a list of twenty numbers

with an interval of only thirty seconds between readings, and needed

eleven readings to master the list. But a similar list, with

five-minute intervals, was mastered in six readings; and the number of

readings went down to five with an interval of ten minutes, and

remained the same for longer intervals up to two days. With this

particular sort of lesson, then, ten minutes was a long enough

interval, and two days not too long, to give the greatest economy of

time spent in actual study.

In a somewhat different experiment in another laboratory, lists of

nonsense syllables were studied either two, four, or eight times in

immediate succession, and this was repeated each day till a total of

twenty-four readings had been given to each list; then, one day after

the last reading of each list, the subjects were tested as to their

memory of it. The result appears in the adjoining table.

EFFECT OF SPACED STUDY ON ECONOMY OF MEMORIZING (From Jost)

Distribution of

the 24 readings Total score Total score

of Mr. B. of Mr. M.

8 readings a day for 3 days 18 7

6 readings a day for 4 days 39 31

2 readings a day for 12 days 58 55

The widest distribution gave the best score. Undoubtedly, then, if you

had to memorize a poem or speech, you would get better value for time

spent if you read it once or twice at a time, with intervals of

perhaps a day, than if you attempted to learn it at one continuous

sitting. What exact spacing would give the very greatest economy would

depend on the length and character of the lesson.

Spaced study also fixes the matter more durably. Every student knows

that continuous "cramming" just before an {343} examination, while it

may accomplish its immediate purpose, accomplishes little for

permanent knowledge.

When we say that spaced repetitions give best results in memorizing,

that does not mean that study generally should be in short periods

with intervals of rest; it says nothing one way or the other on that

question. The probability is, since most students take a certain time

to get well "warmed up" to study, that fairly long periods of

consecutive study would yield larger returns than the same amount of

time divided into many short periods. What we have been saying here is

simply that repetition of the _same material_ fixes it better in

memory, when an interval (not necessarily an empty interval) elapses

between the repetitions.

Whole versus part learning.

In memorizing a long lesson, is it more economical to divide it into

parts, and study each part by itself till mastered, or to keep the

lesson entire and always go through the whole thing? Most of us would

probably guess that study part by part would be better, but

experimental results have usually been in favor of study of the whole.

If you had to memorize 240 lines of a poem, you would certainly be

inclined to learn a part at a time; but notice the following

experiment. A young man took two passages of this length, both from

the same poem, and studied one by the whole method, the other by the

part method, in sittings of about thirty-five minutes each day. His

results appear in the table.

LEARNING PASSAGES OF 240 LINES, BY WHOLE AND PART METHODS

(Pyle and Snyder)

Method of study Number of days Total number of

required minutes required

30 lines memorized per day,

then whole reviewed till it

could be recited 12 431

3 readings of whole per day

till it could be recited 10 348

{344}

Here there was an economy of eighty-three minutes, or nearly twenty

per cent., by using the whole method as against the part method.

Similar experiments have regularly given the same general result.

However, the matter is not quite so simple, as, under certain

conditions, the results tend the other way. Let us consider a very

different type of learning test. A "pencil maze", consisting of

passages or grooves to be traced out with a pencil, while the whole

thing was concealed from the subject by a screen, was so arranged that

it could be divided into four parts and each part learned separately.

Four squads of learners were used. Squads A and B learned the maze as

a whole, squads C and D part by part. Squads A and C learned by spaced

trials, two trials per day. Squad B learned the whole thing at one

sitting; while squad D, which came off best of all, learned one part a

day for four days, and on the fifth day learned to put the parts

together. The results appear in the adjoining table, which shows the

average time required to master the maze by each of the four methods.

PART AND WHOLE LEARNING, SPACED AND UNSPACED,

IN THE PENCIL MAZE (From Pechstein)

Spaced trials Unspaced trials

Whole learning A 641 seconds B 1250 seconds

Part learning C 1220 seconds D 538 seconds

When the trials were spaced, the whole method was much the better; but

when the trials were bunched, the part method was much the better;

and, on the whole, the unspaced part learning was the best of all.

Thus the result stands in apparent contradiction with two accepted

laws: that of the advantage of spaced learning, and that of the

advantage of whole learning.

This contradiction warns us not to accept the "laws" {345} too

blindly, but rather to analyze out the factors of advantage in each

method, and govern ourselves accordingly. Among the factors involved

are the following four:

(1) The factor of interest, confidence and visible accomplishment--the

emotional factor, we might call it. This is on the side of part

learning, especially with beginners, who soon feel out of their depth

when wading into a long lesson, and lose hope of ever learning it in

this way. This factor is also largely on the side of unspaced as

against spaced learning, when the part studied is of moderate length

and when there are recitations to keep up the interest; for when the

learner sees he is getting ahead, he would rather keep right on than

wait for another day to finish. To have a task that you can hope to

accomplish at once, and to attack it with the intention of mastering

it at once, is very stimulating.

(2) The factor of recency, of "striking while the iron is hot". When

an act has just been successfully performed it can easily be repeated,

and when a fact has just been observed it can readily be put to use.

This factor is clearly on the side of unspaced learning; and it is

also on the side of part learning, since by the time you have gone

through the whole long lesson and got back to where you are now, the

recency value of what you have just now accomplished will have

evaporated.

(3) The factor of meaning, outlining and broad relationships. This is

on the side of whole learning, for it is when you are going through

the whole that you catch its general drift, and see the connections of

the several parts and their places in the whole. This factor is so

important as to outweigh the preceding two in many cases, especially

with experienced learners dealing with meaningful material. Even if

you should prefer the part method, you would be wise to begin by a

careful survey of the whole.

{346}

(4) The factor of permanency. This is something "physiological", and

it is on the side of spaced learning. The muscles profit more by

exercise with intervals of rest than by a large amount of continuous

exercise, and no athlete would think for a moment of training for a

contest of strength by "cramming" for it. Apparently the neurones obey

the same law as the muscles, and for that reason spaced learning gives

more durable results than unspaced.

Unintentional Learning

What we have been examining is intentional memorizing, with the "will

to learn" strongly in the game. The assertion has sometimes been made

that the will to learn is necessary if any learning is to be

accomplished. We must look into this matter, for it has an important

bearing on the whole question of the process of learning.

There is a famous incident that occurred in a Swiss psychological

laboratory, when a foreign student was supposed to be memorizing a

list of nonsense syllables. After the list had been passed before him

many times without his giving the expected signal that he was ready to

recite, the experimenter remarked that he seemed to be having trouble

in memorizing the syllables. "Oh! I didn't understand that I was to

learn them", he said, and it was found that, in fact, he had made

almost no progress towards learning the list. He had been observing

the separate syllables, with no effort to connect them into a series.

Another incident: subjects were put repeatedly through a "color naming

test", which consisted of five colors repeated in irregular order, the

object being to name the one hundred bits of color as rapidly as

possible. After the subjects had been through this test over two

hundred times, you would think they could recite it from memory; but

not {347} at all! They had very little memory of the order of the bits

of color. Their efforts had been wholly concentrated upon naming the

bits as seen, and not in connecting them into a series that could be

remembered.

The experiment described a few pages back on "paired associates" is

another case in point. The subjects memorized the pairs, but made no

effort to connect the pairs in order, and consequently were not able

later to remember the order of the pairs.

Many somewhat similar experiments have been performed, with the object

of measuring the reliability of the testimony of eye-witnesses; and it

has been found that testimony is very unreliable except for facts that

were specifically noted at the time. Enact a little scene before a

class of students who do not suspect that their memory of the affair

is later to be tested, and you will find that their memory for many

facts that were before their eyes is hazy, absent, or positively

false.

These facts all emphasize the importance of the will to learn. But let

us consider another line of facts. An event occurs before our eyes,

and we do notice certain facts about it, not with any intention of

remembering them later, but simply because they arouse our interest;

later, we recall such facts with great clearness and certainty. Or, we

hear a tune time after time, and gradually come to be able to sing it

ourselves, without ever having attempted to memorize it. Practically

all that the child learns in the first few years of his life, he

learns without any "will to learn".

What is the difference between the case where the will to learn is

necessary, and the case where it is unnecessary? The difference is

that in the one case we observe facts for the purpose of committing

them to memory, and in the other case we observe the facts without any

such intention. In both cases we remember what we have definitely

observed, {348} and fail to remember what we have not observed.

Sometimes, to be sure, it is not so much observation as doing that is

operative. We may make a certain reaction with the object of learning

it so as to make it later, or we may make the reaction for some other

reason; but in either case we learn it.

What is essential, then, is not the will to learn, but the doing and

observing. The will to learn is sometimes important, as a directive

tendency, to steer doing and observing into channels relevant to the

particular memory task that we need to perform. But committing to

memory seems not to be any special form of activity; rather, it

consists of reactions that also occur without any view to future

remembering. Not only do we learn _by_ doing and observing, but doing

and observing _are_ learning.

Retention

We come now to the second of our four main problems, and ask how we

retain, or carry around inside of us, what we have learned. The answer

is, not by any process or activity. Retention is a resting state, in

which a learned reaction remains until the stimulus arrives that can

arouse it again. We carry around with us, not the reaction, but the

machinery for making the reaction.

Consider, for example, the retention of motor skill. A boy who has

learned to turn a handspring does not have to keep doing it all the

time in order to retain it. He may keep himself in better form by

reviewing the performance occasionally, but he retains the skill even

while eating and sleeping. The same can be said of the retention of

the multiplication table, or of a poem, or of knowledge of any kind.

The machinery that is retained consists very largely in brain

connections. Connections formed in the process of {349} learning

remain behind in a resting condition till again aroused to activity by

some appropriate stimulus.

But the machinery developed in the process of learning is subject to

the wasting effects of time. It is subject to the law of "atrophy

through disuse". Just as a muscle, brought by exercise into the pink

of condition, and then left long inactive, grows weak and small, so it

is with the brain connections formed in learning. With prolongation of

the condition of rest, the machinery is less and less able to

function, till finally all retention of a once-learned reaction may be

lost.

But _is_ anything once learned ever completely forgotten and lost?

Some say no, being strongly impressed by cases of recovery of memories

that were thought to be altogether gone. Childhood experiences that

were supposed to be completely forgotten, and that could not at first

be recalled at all, have sometimes been recovered after a long and

devious search. Sometimes a hypnotized person remembers facts that he

could not get at in the waking state. Persons in a fever have been

known to speak a language heard in childhood, but so long disused as

to be completely inaccessible in the normal state. Such facts have

been generalized into the extravagant statement that nothing once

known is ever forgotten. For it is an extravagant statement. It would

mean that all the lessons you had ever learned could still be recited,

if only the right stimulus could be found to arouse them; it would

mean that all the lectures you ever heard (and attended to) are still

retained, that all the stories you ever read are still retained, that

all the faces you ever noticed are still retained, that all the scenes

and happenings that ever got your attention could still be revived if

only the right means were taken to revive them. There is no evidence

for any such extreme view.

The modern, scientific study of this matter began with {350}

recognizing the fact that there are _degrees of retention_, ranging

all the way from one hundred per cent, to zero, and with the invention

of methods of measuring retention. Suppose you have memorized a list

of twenty numbers some time ago, and kept a record of the time you

then took to learn it; since when you have not thought of it again.

[Illustration: Fig. 53.--(From Ebbinghaus.) The curve of forgetting.

The curve sinks at first rapidly, and then slowly, from the 100 per

cent line towards the zero line, 100 per cent. here meaning perfect

retention, and 0 no retention.]

On attempting now to recite it, you make no headway and are inclined

to think you have entirely forgotten it. But, finding the list again,

you _relearn_ it, and probably find that your time for relearning is

less than the original learning time--unless the lapse of time has run

into months. Now consider--if no time at all were needed for

relearning, because the list could be recited easily without, your

retention would be one hundred per cent. If, on the contrary, it took

you just as long now to relearn as it did originally to learn, the

retention would be zero. If it takes you now two-thirds as long to

relearn as it originally took to learn, then {351} one-third of the

work originally done on the list does not have to be done over, and

_this saving is the measure of retention_.

By the use of this method, the curve of retention, or curve of

forgetting, as it is also called, has been determined. It is a curve

that first goes down steeply, and then more and more gradually, till

it approximates to zero; which means that the loss of what has been

learned proceeds rapidly at first and then more and more slowly.

The curve of forgetting can be determined by other methods besides the

saving method--by the recall method or by the recognition method; and

data obtained by these methods are given in the adjoining tables. It

will be seen that the different methods agree in showing a curve that

falls off more rapidly at first than later. More is lost in the first

hour than in the second hour, and more in the first week than in the

second week. Few of the experiments have been continued long enough to

bring the curve actually to the zero line, but it has come very close

to that line in tests conducted after an interval of two to four

months.

PER CENT. OF WORDS RECOGNIZED AT DIFFERENT INTERVALS AFTER BEING SEEN

(From Strong)

Interval between Per cent. recognized with

exposure and test certainty and correctness

15 secs. 84

5 min. 73

15 min. 62

30 min. 58

1 hour 56

2 hours 50

4 hours 47

8 hours 40

12 hours 38

1 day 29

2 days 24

4 days 19

7 days 10

The subject read a list of 20 disconnected words once through,

giving careful attention to each word. Immediately at the close of

the reading he performed an example in mental arithmetic, to prevent

his reviewing the list of words mentally. After an interval, he was

shown these {352} twenty words mixed with twenty others, and had to

pick out those he surely recognized as having been shown before.

Many lists were used, for testing after the different intervals.

Five adult subjects took part in the experiment, and in all 15 lists

were used with each interval; the per cents. given in the table are

the averages for the 15 lists.

THE PER CENT. OF ERROR IN RECALLING DETAILS OF A

PICTURE AFTER DIFFERENT INTERVALS OF TIME

(From Dallenbach)

Time of test Per cent, of error Per cent of error

in spontaneous in answering

recall questions regarding

the picture

Immediately after exposure 10 14

After 5 days 14 18

After 15 days 18 20

After 46 days 22 22

The picture was placed in the subject's hands, and he examined it

for one minute, at the end of which time he wrote down as complete a

description of the picture as possible, and then answered a set of

sixty questions covering all the features of the picture. After five

days he was retested in the same way, and again after fifteen days,

etc. In one respect this is not a typical memory experiment, since

the test after five days would revive the subject's memory of the

picture and slacken the progress of forgetting. The experiment

corresponds more closely to the conditions of ordinary life, when we

do recall a scene at intervals; or it corresponds to the conditions

surrounding the eye-witness of a crime, who must testify regarding

it, time after time, before police, lawyers and juries. However, the

subjects in this experiment realized at the time that they were to

be examined later, and studied the picture more carefully than the

eye-witness of a crime would study the event occurring before his

eyes; so that the per cent. of error was smaller here than can be

expected in the courtroom.

It must be understood that this classical curve of forgetting only

holds good, strictly, for material that has _barely_ been learned.

Reactions that have been drilled in thoroughly and repeatedly fall off

very slowly at first, and the further course of the curve of

forgetting has not been accurately followed in their case. A typist

who had spent perhaps two hundred hours in drill, and then dropped

typewriting for a year, recovered the lost ground in less than an hour

of fresh practice, so that the retention, as measured by the saving

method, was over ninety-nine per cent.

Somewhat different from the matter of the curve of forgetting is the

question of the _rate of forgetting_, as {353} dependent on various

conditions. The rate of forgetting depends, first, on the thoroughness

of the learning, as we have just seen. It depends on the kind of

material learned, being very much slower for meaningful than for

nonsense material, though both have been learned equally well. Barely

learned nonsense material is almost entirely gone by the end of four

months, but stanzas of poetry, just barely learned, have shown a

perceptible retention after twenty years.

Very fortunately, the principles of economy of memorizing hold good

also for retention. Forgetting is slower when relationships and

connections have been found in the material than when the learning has

been by rote. Forgetting is slower after active recitation than when

the more passive, receptive method of study has been employed.

Forgetting is slower after spaced than after unspaced study, and

slower after whole learning than after part learning.

An old saying has it that quick learning means quick forgetting, and

that quick learners are quick forgetters. Experiment does not wholly

bear this out. A lesson that is learned quickly because it is clearly

understood is better retained than one which is imperfectly understood

and therefore slowly learned; and a learner who learns quickly because

he is on the alert for significant facts and connections retains

better than a learner who is slow from lack of such alertness. The

wider awake the learner, the quicker will be his learning and the

slower his subsequent forgetting; so that one is often tempted to

admonish a certain type of studious but easy-going person, "for

goodness' sake not to dawdle over his lessons", with any idea that the

more time he spends with them the longer he will remember them. More

gas! High pressure gives the biggest results, provided only it is

directed into high-level observation, and does not simply generate

fear and worry and a rattle-brained frenzy of rote learning.

{354}

Recall

Having committed something to memory, how do we get it back when we

want it? To judge from such simple cases as the animal's performance

of a previously learned reaction, all that is necessary is a

_stimulus_ previously linked with the response. How, for example,

shall we get the cat to turn the door-button, this being an act that

the cat has previously learned? Why, we put the cat into the same

cage, i.e., we supply the stimulus that has previously given the

reaction, and trust to it to give the same reaction again. The

learning process has attached this reaction to this stimulus. Now can

we say the same regarding material committed to memory by the human

subject? Is recall a species of learned reaction that needs only the

linked stimulus to arouse it?

If you have learned and still retain a list of numbers or syllables,

you can recite it on thinking of it, on hearing words that identify it

in your mind, or on being given the first few items in the list as a

start. The act of reciting the list became linked, during the

learning, with the thought of the list, with words signifying this

particular list, and with the first items of the list; therefore,

these stimuli can now arouse the reaction of reciting the list. As you

advance into the list, reciting it, the parts already recited act as

stimuli to keep you going forward. In the same way, if you have

memorized Hamlet's soliloquy, this title serves as the stimulus to

make you recall the beginning of the speech and that in turn calls up

the next part and so on; or, if you have analyzed the speech into an

outline, the title calls up the outline and the outline acts as the

stimulus to call up the several parts that were attached to the

outline in the process of memorization. When one idea calls up

another, the first acts as a stimulus and the second is a {355}

response previously attached to this stimulus. In general, then,

recall is a learned response to a stimulus.

There is an exceptional case, where recall seems to occur without any

stimulus. This form of recall goes by the name of _perseveration_, and

a good instance of it is the "running of a tune in the head", shortly

after it has been heard. Another instance is the vivid flashing of

scenes of the day before the "mind's eye" as one lies in bed before

going to sleep. It appears as if the sights or sounds came up of

themselves and without any stimulus. Possibly there is some vague

stimulus which cannot itself be detected. Only a slight stimulus would

be needed, because these recent and vivid experiences are so easily

aroused.

Difficulties in recall.

Sometimes recall fails to materialize when we wish it and have good

reason for expecting it. We know this person's name, as is proved by

the fact that we later recall it, but at the moment we cannot bring it

up. We know the answer to this examination question, but in the heat

of the examination we give the wrong answer, though afterwards the

right answer comes to mind. This seldom happens with thoroughly

learned facts, but frequently with facts that are moderately well

known. Some sort of inhibition or interference blocks recall.

One type of interference is emotional. Fear may paralyze recall.

Anxious self-consciousness, or stage fright, has prevented the recall

of many a well-learned speech, and interfered with the skilful

performance of many a well-trained act.

Distraction is an interference, since it keeps the stimulus from

exerting its full effect. Sometimes the stimulus that is present has

been linked with two or more responses, and these get in each other's

way; as you will sometimes hear a speaker hesitate and become confused

from having two ways {356} of expressing the same thought occur to him

at almost the same instant.

Helps in recall.

There are no sure rules for avoiding these intricate interferences;

and, in general, recall being a much less manageable process than

memorizing, we do not have anything like the same mass of practical

information regarding it. One or two suggestions have some value,

however.

(1) Give the stimulus a good chance. Look squarely at the person whose

name you wish to recall, avoiding doubt as to your ability to recall

it; for doubt is itself a distraction. Put yourself back into the time

when you formerly used this person's name. In extemporaneous speaking,

go ahead confidently, avoid worry and self-consciousness, and, full of

your subject, trust to your ideas to recall the words as needed. Once

carried away with his subject, a speaker may surprise himself by his

own fluency.

(2) Drop the matter for a while, and come back to it afresh.

Sometimes, when you cannot at once recall a name, it does no good to

keep doggedly hunting, while half an hour later you get it without the

least trouble. The explanation of this curious phenomenon is found in

interference and the dying out of interference. At your first attempt

to recall the name, you simply got on the wrong track, and thus gave

this wrong track the "recency" advantage over the right track; but

this temporary advantage fades out rapidly with rest and leaves the

advantage with the track most used in the past.

The rule to drop a matter when baffled and confused, and take it up

again when fresh, can be used in more complex cases than hunting for a

name. When, in trying to solve any sort of problem, you find yourself

in a rut, about the only escape is to back off, rest up, and make an

entirely fresh start.

{357}

Recognition

The fourth question propounded at the beginning of the chapter, as to

how we can know that the fact now recalled is what we formerly

committed to memory and now wish to recall, is part of the larger

question of how we recognize. What we recognize includes not only

facts recalled, but also facts not recalled but presented a second

time to the senses. Recognition of objects seen, heard, touched, etc.,

is the most rudimentary form of memory. The baby shows signs of

recognizing persons and things before he shows signs of recall. A

little later, he recognizes and understands words before he begins to

speak (recall) them; and everybody's vocabulary of recognized words

remains much greater than his speaking vocabulary. We recognize faces

that we could not recall, and names that we could not recall. In

short, recognition is easier than recall.

Consequently any theory of recognition that makes it depend on recall

can scarcely be correct. One such theory held that an object is

recognized by recalling its original setting in past experience; an

odor would be recognized by virtue of recalling the circumstances

under which it was formerly experienced. Now sometimes it does happen

that an odor which seems familiar, but cannot be identified, calls up

a past experience and thus is fully recognized; but such "indirect

recognition" is not the usual thing, for direct recognition commonly

takes place before recall of the past experience has time to occur.

You see a person, and know him at once, though it may require some

moments before you can recall where and when you have seen him before.

Recognition may be more or less complete. At its minimum, it is simply

a "feeling of familiarity" with the object; at its maximum it is

locating the object precisely in your autobiography. You see a man,

and say, "He looks {358} familiar, I must have seen him somewhere",

and then it dawns on you, "Oh! yes, now I know exactly who he is; he

is the man who . . ." Between these extremes lie various degrees of

recognition. This man seems to be some one seen recently, or a long,

long time ago, or at the seashore, or as a salesman in a store; or as

some one you looked up to, or felt hostility towards, or were amused

at; and often these impressions turn out to be correct, when you

succeed in fully recognizing the person. These impressions resemble

the first signs of recognition in the baby's behavior; you say that

the baby remembers people because he smiles at one who has pleased him

before, and shrinks from one who has displeased him.

Recognition described in terms of stimulus and response.

Recognition is a form of learned response, depending on previous

reaction to the object recognized. To recognize an object is to

respond to it as we responded before--except for the feeling of

familiarity, which could not occur the first time we saw the object.

But notice this: though the object is the same identical object it was

before, it may have changed somewhat. At least, its setting is

different; this is a different time and perhaps a different place, and

the circumstances are bound to be more or less different. In spite of

this difference in the situation, we make the same response as before.

Now, the response we made to the object in its original setting was a

response to the whole situation, object _plus_ setting; our response

to the object was colored by its setting. When we now recognize the

object, we make the same response to the object in a different

setting; the response originally called out by the object _plus_ its

setting is now aroused by the object alone. Consequently we have an

uneasy feeling of responding to a situation that is not present. {359}

This uneasy feeling is the feeling of familiarity in its more haunting

and "intriguing" form.

We see some one who seems familiar and who arouses a hostile attitude

in us that is not accounted for in the least by his present actions.

We have this uneasy feeling of responding to a situation that is not

present, and cannot rest till we have identified the person and

justified our hostile attitude.

Or, we see some one who makes us feel as if we had had dealings with

him before in a store or postoffice where he must have served us; we

find ourselves taking the attitude towards him that is appropriate

towards such a functionary, though there is nothing in his present

setting to arouse such an attitude. Or, we see some one in the city

streets who seems to put us back into the atmosphere of a vacation at

the seashore, and by searching our memory we finally locate him as an

individual we saw at such and such a resort. At other times, the

feeling of familiarity is rather colorless, because the original

situation in which the person was encountered was colorless; but we

still have the feeling of responding to something that is not present.

We make, or start to make, the same response to the person that we

originally made to him _plus_ his setting, and this response to

something that is not there gives the feeling of familiarity.

When we see the same person time after time in the same setting, as

when we go into the same store every morning and buy a paper from the

same man, we cease to have any strong feeling of familiarity at sight

of him, the reason being that we are always responding to him in the

same setting, and consequently have no feeling of responding to

something that is not there. But if we see this same individual in a

totally different place, he may give us a queer feeling of

familiarity. When we see the same person time after time {360} in

various settings, we end by separating him from his surroundings and

responding to him alone, and therefore the familiarity feeling

disappears.

Complete recognition, or "placing" the object, involves something more

than these feelings and rudimentary reactions. It involves the recall

of a context or scheme of events, and a fitting of the object into the

scheme.

Memory Training

The important question whether memory can be improved by any form of

training breaks up, in the light of our previous analysis, into the

four questions, whether memorizing can be improved, whether the power

of retention can be improved, whether recall can be improved, and

whether recognition can be improved. As to recognition, it is

difficult to imagine how to train it; the process is so elusive and so

direct. It has been found, however, that practice in recognizing a

certain class of objects improves one's standards of judgment as to

whether a feeling of familiarity is reliable or not; it enables one to

distinguish between feelings that have given correct recognitions and

the vaguer feelings that often lead one astray.

As to recall, certain hints were given above as to the efficient

management of this process, and probably practice in recalling a

certain sort of facts, checked up by results, would lead to

improvement.

As to retention, since this is not a performance but a resting state,

how could we possibly go about to effect an improvement? One

individual's brain is, to be sure, more retentive than another's; but

that seems a native trait, not to be altered by training.

On the other hand, the process of committing to memory, being a

straightforward and controllable activity, is {361} exceedingly

susceptible to training, and it is there, for the most part, that

memory training should be concentrated in order to yield results. It

does yield marked results. In the laboratory, the beginner in learning

lists of nonsense syllables makes poor work of it. He is emotionally

wrought up and uncertain of himself, goes to work in a random way

(like any beginner), perhaps tries to learn by pure rote or else

attempts to use devices that are ill-adapted to the material, and has

a slow and tedious job of it. With practice in learning this sort of

material, he learns to observe suitable groupings and relationships,

becomes sure of himself and free from the distraction of emotional

disturbance, and may even come to enjoy the work. Certainly he

improves greatly in speed of memorizing nonsense syllables. If,

instead, he practises on Spenser's "Faery Queen", he improves in that,

and may cut down his time for memorizing a twelve-line stanza from

fifteen minutes to five. This improvement is due to the subject's

finding out ways of tackling this particular sort of material. He gets

used to Spenser's style and range of ideas. And so it is with any kind

of material; practice in memorizing it brings great improvement in

memorizing that particular material.

Whether practice with one sort of material brings skill that can be

"transferred", or carried over to a second kind of material, is quite

another question. Usually the amount of _transfer_ is small compared

with the improvement gained in handling the first material, or

compared with the improvement that will result from specific training

with the second kind. What skill is transferred consists partly of the

habit of looking for groupings and relationships, and partly in the

confidence in one's own ability as a memorizer. It is really worth

while taking part in a memory experiment, just to know what you can

accomplish after a little training. Most persons who complain of poor

memory would be {362} convinced by such an experiment that their

memory was fundamentally sound. But these laboratory exercises do not

pretend to develop any general "power of memory", and the much

advertised systems of memory training are no more justified in such a

claim. What is developed, in both cases, is skill in memorizing

certain kinds of material so as to pass certain forms of memory test.

One who suffers from poor memory for any special material, as names,

errands, or engagements, probably is not going to work right in

committing the facts to memory; and if he gives special attention to

this particular matter, keeping tab on himself to see whether he

improves, he is likely to find better ways of fixing the facts and to

make great improvement. It was said of a certain college president of

the older day that he never failed to call a student or alumnus by

name, after he had once met the man. How did he do it? He had the

custom of calling each man in the freshman class into his office for a

private interview, during which, besides fatherly advice, he asked the

man personal questions and studied him intently. He was interested in

the man, he formed a clear impression of his personality, and to that

personality he carefully attached the name. Undoubtedly this able

scholar was possessed of an unusually retentive memory; but his memory

for names depended largely on his method of committing them to memory.

Contrast this with the casual procedure of most of us on being

introduced to a person. Perhaps we scarcely notice the name, and make

no effort to attach the name to the personality. To have a good memory

for names, one needs to give attention and practice to this specific

matter. It is the same with memory for errands; it can be specifically

trained. Perhaps the best general hint here is to connect the errand

beforehand in your mind with the {363} place where you should think,

during the day, to do the errand.

Often some little _mnemonic system_ will help in remembering

disconnected facts, but such devices have only a limited field of

application and do not in the least improve the general power of

memory. Some speakers, in planning out a speech, locate each

successive "point" in a corner of the hall, or in a room of their own

house; and when they have finished one point, look into the next

corner, or think of the next room, and find the following point there.

It would seem that a well-ordered discourse should supply its own

logical cues so that such artificial aids would be unnecessary.

In training the memory for the significant facts that constitute the

individual's knowledge of his business in life, the best rule is to

systematize and interrelate the facts into a coherent whole. Thus, a

bigger and stronger stimulus is provided for the recall of any item.

This, along with the principles of "economy" in memorizing, is the

best suggestion that psychology has to make towards memory

improvement.

{364}

EXERCISES

1. In outlining the chapter, regroup the material so as to separate

the practical applications from the description of memory

processes. This gives you two main heads: A. Memory processes, and

B. The training and management of memory. Each of these main heads

should be divided into four sub-heads: Memorizing, retention, etc.,

and the information contained in the chapter grouped under these

sub-heads.

2. Disorders of memory can be classified under the four heads of

disorders of learning, of retention, of recall and of recognition.

Where would you place each of the following?

(a) Aphasia, where, through brain injury, the subject's

vocabulary is very much reduced.

(b) The condition of the very old person, who cannot remember

what has happened during the day, though he still remembers

experiences of his youth.

(c) The "feeling of having been there before", in which you have

a weird impression that what is happening now has happened in

just the same way before, as if events were simply repeating

themselves.

(d) The loss of memory which sometimes occurs after a physical

or emotional shock, or after a fever, and which passes away

after a time.

3. How fully can you recall what happened on some interesting

occasion when you were a child of 5-8 years? Dwell on the

experience, and see whether you get back more than at first seemed

possible. Try the same with an experience of five years ago.

4. If a student came to you for advice, complaining of poor memory,

and said that though he put hours and hours on a lesson and read it

over many times, still he failed on it, what questions would you

ask regarding his method of study, and what suggestions would you

offer?

5. An experiment on memorising lists of numbers. Prepare several

lists of 20 digits, and shuffle them; draw out one and take your

time for learning it to the point of perfect recitation. Write an

introspective account of the process. Repeat with a second list

6. An experiment in memorizing word-pairs. Prepare 20 pairs of

words as follows: take 20 cards or slips of paper, and write a

different word on each. Then turn them over, shuffle, and write

another word on the back of each. Thus, though you may know what

words you have written, you do not how how they are paired; and now

your job is to learn the pairs. Note starting time, take the first

card and look at both {365} sides, and study the pair of words on

this card for about 5 seconds, passing then to the second card, and

so on through the pack. Shuffle the pack, take the top card and

give yourself about 5 seconds to recall the word on the reverse,

then turning the card over and reading it. Proceed in this way

through the pack, shuffle again, and repeat. Continue thus till you

score 100 per cent. Note total time required, and report on process

of memorizing.

7. Memorizing a series of related words. Prepare a list of 40

words, as follows: first write the numbers 1 to 40 in a column;

then write any word for No. 1; for No. 2, write some word closely

related to No. 1; for No. 3 some word closely related to No. 2; and

so on. Your list, for example, might begin like this: house, roof,

chimney, soot, fire, coal, mine, miner, strike, arbitration, etc.

Having finished writing your list, cover it and see how much of it

you can recite without further study, and how long it takes you to

complete the memorizing. Explain the results obtained.

8. Plot the curve of forgetting from the following data, which give

the per cent, of retention of stanzas of a poem at different

intervals after the end of memorizing.

after 1 day 79%

after 2 days 67%

after 6 days 42%

after 14 days 30%

after 30 days 24%

REFERENCES

Ebbinghaus, _On Memory_, 1885, translated by Ruger and Bussenius,

1918. This is the pioneer experimental study of memory, and is still

worth reading, and is not specially hard reading.

James's chapter on Memory, in Vol. I of his _Principles of

Psychology_, 1890, is still one of the best references, and contains

some important remarks on the improvement of memory.

Of the numerous special studies on memory, mention may be made of that

by Arthur I. Gates, _Recitation as a Factor in Memorizing_, 1917,

which, on pp. 65-104, gives a valuable account of the various devices

used by one who is memorizing.

For the psychology of testimony, see G. M. Whipple's article on "The

Obtaining of Information: Psychology of Observation and Report", in

the _Psychological Bulletin_ for 1918, Vol. 15, pp. 217-248,

especially pp. 233-248. See also a popularly written account of the

matter by Münsterberg, in _On the Witness Stand_, 1908, pp. 15-69.

{366}

CHAPTER XV

ASSOCIATION AND MENTAL IMAGERY

SOMETHING ABOUT THINKING AS RELATED TO MEMORY

Memory plays a part, not only in "memory work", and not only in

remembering particular past experiences, but in all sorts of thinking.

Recall furnishes the raw material for thought. A large share of any

one's daily work, whether it be manual or mental, depends on the

recall of previously learned reactions. Most of the time, though we

are not exactly trying to remember facts committed to memory, we are

recalling what we have previously learned, and utilizing the recalled

material for our present purposes. For example, in conversation we

recall words to express our meaning, and we recall the meanings of the

words we hear. In adding a column of figures, we recall the sums of

the numbers. In cooking a meal, we recall the ingredients of the dish

we wish to prepare, and the location of the various materials and

utensils required for our purpose. In planning a trip, we recall

places and routes. Any sort of problem is solved by means of recalled

facts put together in a new way. A writer in constructing a story puts

together facts that he has previously noted, and any work of the

imagination consists of materials recalled from past experience and

now built into a new composition.

What Can Be Recalled

If recall is so important in thinking and acting, it is worth while to

make a survey of the materials that recall {367} furnishes. In

general, using the term "recall" rather broadly, we say that any

previously learned reaction may be recalled. Writing _movements_ may

be said to be recalled when we write, and speech movements when we

speak. "Higher units", like the word habits and phrase habits of the

telegrapher and typist, are in a broad sense recalled whenever they

are used. The typist does not by any means recall the experience of

learning a higher unit, but he calls into action again the response

that he has learned to make. In the same way, the word habits and

phrase habits of vocal speech are called into action, i.e., recalled,

whenever we speak.

Besides these motor reactions, _tendencies_ to reaction can be

recalled. The attitude of hostility that may have become habitual in

us towards a certain person, or towards a certain task, is called into

activity at the mention of that person or task. The acquired interest

in architecture that we may have formed by reading or travel is

revived by the sight of an ambitious group of buildings. A slumbering

purpose may be recalled into activity by some relevant stimulus.

Observed _facts_ can be recalled, and this is the typically human form

of recall. In animals, we see the recall of tendencies and of learned

movements, but no clear evidence of the recall of observed facts. To

be recalled with certainty, a fact must have been definitely noted

when it was before us. If we have definitely noted the color of a

person's eyes, we are in a position to testify that his eyes are

brown, for example; otherwise, we may say that we think probably his

eyes are brown; because we have certainly noticed that he is dark, and

the dark eyes fit best into this total impression.

We say that a fact is recalled when we think of it without its being

present to the senses. While the original {368} observation of the

fact was a response to a sensory stimulus, the recall of it is a

response to some other stimulus, some "substitute stimulus". When John

is before me, I observe that his eyes are brown in response to a

visual stimulus; but I later recall this fact in response simply to

the name "John", or in response to the question as to what is the

color of John's eyes. I see what a square is by seeing squares and

handling them, and later I get this idea simply in response to the

word "square" in conversation or reading.

Memory Images

Now, can _sensations_ be recalled, can they be aroused except by their

natural sensory stimuli? Can you recall the color blue, or the sound

of a bugle, or the odor of camphor, or the feel of a lump of ice held

in the hand? Almost every one will reply "Yes" to some at least of

these questions. One may have a vivid picture of a scene before the

"mind's eye", and another a realistic sound in the "mind's ear", and

they may report that the recalled experience seems essentially the

same as the original sensation. Therefore, sensory reactions are no

exception to the rule of recall by a substitute stimulus.

A sensation or complex of sensations recalled by a substitute stimulus

is called a "mental image" or a "memory image".

Individuals seem to differ in the vividness or realism of their memory

images--the likeness of the image to an actual sensation--more than in

any other respect. Galton, in taking a sort of census of mental

imagery, asked many persons to call up the appearance of their

breakfast table as they had sat down to it that morning, and to

observe how lifelike the image was, how complete, how adequate in

respect to color, how steady and lasting, and to compare {369} the

image in these respects with the sensory experience aroused by the

actual presence of the scene. Some individuals reported that the image

was "in all respects the same as an original sensation", while others

denied that they got anything at all in the way of recalled sensation,

though they could perfectly well recall definite facts that they had

observed regarding the breakfast table. The majority of people gave

testimony intermediate between these extremes.

Individuals differ so much in this respect that they scarcely credit

each other's testimony. Some who had practically zero imagery held

that the "picture before the mind's eye" spoken of by the poets was a

myth or mere figure of speech; while those who were accustomed to

vivid images could not understand what the others could possibly mean

by "remembering facts about the breakfast table without having any

image of it", and were strongly tempted to accuse them of poor

introspection, if not worse. It is true that in attempting to study

images, we have to depend altogether on introspection, since no one

can objectively observe another person's memory image, and therefore

we are exposed to all the unreliability of the unchecked introspective

method. But at the same time, when you cross-question an individual

whose testimony regarding his imagery is very different from yours,

you find him so consistent in his testimony and so sure he is right,

that you are forced to conclude to a very real difference between him

and yourself. You are forced to conclude that the power of recalling

sensations varies from something like one hundred per cent, down to

practically zero.

Individuals may also differ in the _kind_ of sensation that they can

vividly recall. Some who are poor at recalling visual sensations do

have vivid auditory images, and others who have little of either

visual or auditory imagery call up {370} kinesthetic sensations

without difficulty. When this was first discovered, a very pretty

theory of "imagery types" was built upon it. Any individual, so it was

held, belonged to one or another type: either he was a "visualist",

thinking of everything as it appears to the eyes, or he was an

"audile", thinking of everything according to its sound, or he was a

"motor type", dealing wholly in kinesthetic imagery, or he might, in

rare cases, belong to the olfactory or gustatory or tactile type.

[Illustration: Fig. 54.--Individual differences in mental imagery.

According to the type theory, every individual has a place in one or

another of the distinct groups, visual, auditory, tactile,

kinesthetic, or olfactory. According to the facts, the majority, of

individuals cluster in the middle space, and form a single large

group, though some few are extremely visual, or auditory, etc., in

their imagery. (Figure text: according to the type theory, according to

the facts)]

But the progress of investigation showed, first, that a "mixed type"

must also be admitted, to provide for individuals who easily called up

images of two or more different senses; and, later on, that the mixed

type was the most common. In fact, it is now known to be very unusual

for an individual to be confined to images of a single sense. Nearly

every one gets visual images more easily and frequently than those of

any other sense, but nearly every one has, from time to time,

auditory, kinesthetic, tactile and olfactory images. So that the

"mixed type" is the only real type, the extreme visualist or audile,

etc., being exceptional and not typical.

{371}

Limitations of Imagery

Recalled sensations are commonly inferior to their originals, both in

the enjoyment they afford and in the use that can be made of them.

They are likely to be inferior in several respects.

(1) An image has usually less color, or tone--less body, realism and

full sensory quality--than a sensation aroused by its appropriate

peripheral stimulus. While you may be able to call up a fairly good

image of your absent friend's face, the actual presence of your friend

would be more satisfactory, just as a sensory experience. You may be

able to run over a piece of music "in your head", and if your auditory

imagery is strong you may even run over an orchestral piece, and get

the tone quality of the various instruments; but, after all, such a

mental concert is an imperfect substitute for a real orchestra. You

enjoy a real whiff of the sea more than the best olfactory image you

can summon. There is something lacking in these recalled sensations,

and the trouble seems to be that they are not sensations enough; they

lack sensory body.

(2) Images are apt to be sketchy and lacking in detail, and also

narrow and lacking in background.

(3) Images are apt to be unsteady and fleeting, as compared with

actual sensations. Where the peripheral stimulus, continuing, keeps

the sensation going, the substitute stimulus that recalls a sensation

is not so effective in this respect, any more than in giving body and

detail. In all these respects, an image is less enjoyable and

satisfying than an actual sensation.

(4) On the more practical side, images are inferior to the actual

presence of an object, in that we cannot utilize the image as a source

of new information. {372} We _cannot observe facts_ in the image of a

thing that we have not observed in the actual presence of the thing.

At one of the universities, there is a beautiful library building,

with a row of fine pillars across the front, and the students pass

this building every day and enjoy looking at it. It has long been a

favorite experiment in the psychology classes at that university to

have the students call up an image of the library, and to have them

state how clear their image is, how complete and how vivid. Then they

are asked to count the pillars from their image, and to tell what kind

of capitals the pillars have, and whether the shafts are plain or

fluted. But at this point the students begin to object. "We have never

counted those pillars, and cannot be expected to know the number now."

In fact, few of them give the correct number, and those who have

reported clear and vivid images are little better off in this respect

than those whose images are dim and vague.

The image, then, does not give you facts that you did not observe in

the presence of the object. The substitute stimulus, which now recalls

the image, only recalls responses which you made when the real object

was the stimulus. If you looked at the object simply to get its

general appearance, the general appearance is all you can recall. If

you noted the color of the object, you can probably recall the color.

If you noted such details as the number of pillars, you can recall

these details. But the substitute stimulus that now arouses the image

is by no means the equivalent of the original peripheral stimulus in

making possible a variety of new reactions. Its only linkage is with

reactions actually made by you in response to the real object. The

substitute stimulus, such as the name of a building, became linked

with responses actually made by you, not with responses that you

simply might have made, when the object was present. This important

fact is closely related to the {373} unreliability of testimony that

was mentioned before under the head of "unintentional memory".

[Footnote: See pp. 346-348.] Facts recalled are facts previously

observed.

It is true, of course, that recalled facts can be compared and new

facts be observed by the comparison. We may recall how John looks, and

how James looks, and note the fact, not previously observed, that they

look alike. A great deal can be inferred in this way by a person who

is sitting in his room far from the objects thought about. But this

noting of the relationships of different objects is a very different

matter from observing what is there, in a single object or scene. What

is there can only be observed when you are there.

The Question of Non-Sensory Recall

Many observed facts are not strictly facts of sensation, though

observed by means of the senses. Let us suppose, for an example, that

your attention is caught by the bright green new leaves at the tips of

the branches of an evergreen tree in summer, and that you notice also

the darker green of the older leaves further back along the branches,

and, exploring deeper, find leaves that are dead and brown, while

still further in they have all fallen off, leaving bare branches

reaching back to the trunk; so that you finally "see" how the tree is

constructed, as a hollow cone of foliage supported by an interior

framework of branches. All this has meant a lot of different reactions

on your part, and the final "seeing" of how the tree is constructed

would scarcely be called a sensation, since it has required mental

work beyond that of simply seeing the tree. It is a response

additional to the strictly sensory response of seeing the tree.

Now the question is whether this additional response can be recalled,

without recalling at the same time the primary {374} response of

seeing the tree. Can we recall the fact observed about the tree

without at the same time seeing the tree "in the mind's eye"? Must we

necessarily have an image of the tree when we recall the way the tree

is constructed?

Since getting the general sensory appearance of the tree, and

observing the way it is constructed, are two different responses, it

seems quite conceivable that either fact should be recalled without

the other; and no one doubts that the sensory appearance of the tree

can be recalled without the other observed fact coming up along with

it. But many authorities have held that the non-sensory fact could not

be recalled alone; in other words, they have held that every recalled

fact comes as a sensory image, or with a sensory image. Persons with

ready visual imagery are of course likely to get a visual image with

any fact they may recall. But persons whose visual imagery is hard to

arouse say that they recall facts without any visual image. I who

write these words, being such a person, testify that while I have been

writing and thinking about that tree I have not seen it before my

mind's eye.

It is true, however, that I have had images during this time--auditory

images of words expressing the facts mentioned. Another individual

might have had kinesthetic images instead of either visual or

auditory. But can there be a recall of fact without _any_ sensory

image?

On this question, which has been called the question of "imageless

thought", though it might better be called that of "imageless recall",

controversy has raged and is not yet at rest, so that a generally

accepted conclusion cannot be stated. But the best indications are to

the effect, first, that vague and fleeting images, especially of the

kinesthetic sort, are often present without being detected except by

very fine introspection, some image being pretty sure to come up every

few seconds when we are engaged in silent thought or {375} recall;

but, second, that images are not present every second of the time, and

that at the instant when a non-sensory fact is recalled it is apt to

be alone.

Hallucinations

Since a vivid mental image may be "in all respects the same as an

actual sensation", according to the testimony of some people, the

question arises how, then, an image is distinguished from a sensation.

Well, the image does not usually fit into the objective situation

present to the senses. But if it does fit, or if the objective

situation is lost track of, then, as a matter of fact, the image may

be taken for a sensation.

You see some beautiful roses in the florist's window, and you _smell_

them; the odor fits into the objective situation very well, till you

notice that the shop door is shut and the window glass impervious to

odors, from which you conclude that the odor must have been your

image.

You are lost in thought of an absent person, till, forgetting where

you are, you seem to see him entering the door; he "fits" well enough

for an instant, but then the present situation forces itself upon you

and the image takes its proper place.

You are half asleep, almost lost to the world, and some scene comes

before you so vividly as to seem real till its oddity wakens you to

the reality of your bedroom. Or you are fully asleep, and then the

images that come are dreams and seem entirely real, since contact with

the objective situation has been broken.

Images taken for real things are common in some forms of mental

disorder. Here the subject's hold on objective fact is weakened by his

absorption in his own desires and fears, and he hears reviling voices

and smells suspicious {376} odors or sees visions that are in line

with his desires and fears.

Such false sensations are called "hallucinations". An hallucination is

an image taken for a sensation, a recalled fact taken for a present

objective fact. It is a sensory response, aroused by a substitute

stimulus, without the subject's noticing that it is thus aroused

instead of by its regular peripheral stimulus.

Synesthesia.

Quite a large number of people are so constituted as to hear sounds as

if colored, a deep tone perhaps seeming dark blue, the sound of a

trumpet a vivid red, etc. Each vowel and even each consonant may have

its own special color, which combine to give a complex color scheme

for a word. Numbers also may be colored. This colored hearing is the

commonest form of "synesthesia", which consists in responding to a

stimulus acting on one sense, by sensations belonging to a different

sense. Whether the persons so constituted as to respond in this way

are constituted thus by nature or by experience is uncertain, though

the best guess is that the extra sensations are images that have

become firmly attached to their substitute stimuli during early

childhood.

Free Association

Mental processes that depend on recall are called "associative

processes", since they make use of associations or linkages previously

formed. When some definite interest or purpose steers the associative

processes, we speak of "controlled association", contrasting this with

the "free association" that occurs in an idle mood, when one thought

simply calls up another with no object in view and no more than

fleeting desires to give direction to the sequence of thoughts.

_Revery_ affords the best example of free association. I {377} see my

neighbor's dog out of my window, and am reminded of one time when I

took charge of that dog while my neighbor was away, and then of my

neighbor's coming back and taking the dog from the cellar where I had

shut him up; next of my neighbor's advice with respect to an

automobile collision in which I was concerned; next of the stranger

with whom I had collided, and of the stranger's business address on

the card which he gave me; next comes a query as to this stranger's

line of business and whether he was well-to-do; and from there my

thoughts switch naturally to the high cost of living.

This is rather a drab, middle-aged type of revery, and youth might

show more life and color; but the linkages between one thought and the

next are typical of any revery. The linkages belong in the category of

"facts previously observed". I had previously observed the ownership

of this dog by my neighbor, and this observation linked the dog and

the neighbor and enabled the dog to recall the neighbor to my mind.

Most of the linkages in this revery are quite concrete, but some are

rather abstract, such as the connection between being well-to-do (or

not) and the high cost of living; but, concrete or abstract, they are

connections previously observed by the subject. Sometimes the linkage

keeps the thoughts within the sphere of the same original experience,

and sometimes switches them from one past experience to another, or

even away from any specific past experience to general considerations;

yet always the linkage has this character, that the item that now acts

as stimulus has been formerly combined in observation with the other

item that now follows as the response. One fact recalls another when

the two have been previously observed as belonging together.

But suppose, as is commonly the case, that the fact now present in my

mind has been linked, in different past {378} experiences, with

several different facts. Then two questions demand our attention:

whether all these facts are recalled; and, if not, what gives the

advantage to the fact actually recalled over the others that are not

recalled.

The answer to the first question is plain. The fact first present in

mind does not call up all the associated facts, but usually only one

of them, or at least only one at a time. My neighbor, in the example

given, though previously associated with a dozen other facts, now

calls up but two of these facts, and those two not simultaneously but

one after the other. We see a law here that is very similar to a law

stated under the head of attention. There, we said that of all the

objects before us that might be noticed only one was noticed at a

time; and here we say that of all the objects that might be recalled

to mind by association only one is recalled at a time. Both statements

can be combined into the one general "law of reaction" which was

mentioned before, that of all the responses linked to a given stimulus

(or complex of stimuli) only one is actually aroused at the same

instant, though several may be aroused in succession, provided the

stimulus continues.

In revery, the stimulus usually does not continue. The first fact

thought of gives way to the fact that it recalls, and that to one that

it recalls in turn, and so on, without much dwelling on any fact. But

if we do dwell on any fact--as upon the thought of a certain

person--then this stimulus, continuing to act, calls up in succession

quite a number of associated facts.

If, then, only one of the several facts associated with the stimulus

is recalled at once, our second question presents itself, as to what

are the factors of advantage that cause one rather than another of the

possible responses to occur. The fact first in mind might have called

up any one of several facts, having been linked with each of them in

past {379} experience; and we want to know why it recalls one of these

facts rather than the rest.

The factors of advantage in recall are the factors that determine the

strength of linkage between two facts; and they are:

the _frequency_ with which the linkage has occurred;

the _recency_ with which it has occurred; and

the _intensity_ with which it has occurred.

If I have frequently observed the connection of two facts, the linkage

between them is strong; if I have recently observed their connection,

the linkage between them is strong till the "recency value" dies away;

and if my observation of the connection of the two facts was a vivid

experience, or intense reaction, then, also, the linkage between them

is strong. If these three factors of advantage work together in favor

of the same response, then that response is sure to occur; but if the

three factors pull different ways, we should have to figure out the

balance of advantage before we could predict which of the possible

responses would actually be made. Naturally enough, even the skilful

psychologist is often unable to strike the balance between the three

factors. He does know, however, and all of us know in a practical way,

that strong recency value offsets a lot of frequency; so that a mere

vague allusion to a very recent topic of conversation can be depended

on to recall the right facts to the hearer's mind, even though they

lie outside of his habitual line of interest. "James", by virtue of

frequency, means your brother or friend; but after the lecturer has

been talking about the psychologist James, repetition of this name

infallibly recalls the psychologist to mind.

Besides frequency, recency and intensity, there is, indeed, another

factor to be taken into account; and that is the {380} present state

of the subject's mind. If he is unhappy, unpleasant associations have

the advantage; if happy, pleasant. If he is absorbed in a given

matter, facts related to that matter have the advantage. Frequency,

recency and intensity summarize the _history_ of associations, and

measure their strength as dependent on their history; but the present

state of mind is an additional directive factor, and when it has much

to do with recall, we speak of directed or controlled association.

Before we pass to the topic of controlled association, however, there

is another form of free association, quite different from revery, to

be examined. There is an experiment, called the _free association

test_, in which the subject is given a series of words as stimuli, and

is asked to respond to each word by speaking some other word, the

first that is recalled by the stimulus. No special kind of word need

be given in response, but simply the _first word recalled_. Though

this is called free association, it is controlled to the extent that

the response must be a word, and the result is very different from

revery. Instead of the recall of concrete facts from past experience,

there is recall of words. If you give the subject the stimulus word,

"table", his response is "chair" or "dinner", etc., and often he does

not think of any particular table, but simply of the word. Words are

so often linked one with another that it is no wonder that one recalls

another automatically. What particular word shall be recalled depends

on the frequency, recency and intensity of past linkage.

Though this form of test seems so simple as almost to be silly, it is

of use in several ways. When a large number of stimulus words are

used, and the responses classified, some persons are found to favor

linkages that have a personal significance--"egocentric responses",

these are called--while other persons run to connections that are

{381} impersonal and objective. Thus the test throws some light on the

individual's _habits_ of attention. The test has also a "detective"

use, based upon the great efficacy of the factor of _recency_; you may

be able by it to tell whether an individual has recently had a certain

matter in mind. If he happens to be an individual who has recently

committed some crime, properly selected stimulus words will lead him

to recall the scene of the crime, and thus to make responses that

betray him, unless he checks them and so arouses suspicion by his

hesitation. Another use of the test is for unearthing a person's

emotional "complexes", which of course possess a high _intensity_

value. If the subject shows hesitation and embarrassment in responding

to words referring to money, the indication is that he is emotionally

disturbed over the state of his finances. One person who consulted a

doctor for nervousness made peculiar responses to stimulus words

relating to the family, and was discovered to be much disturbed over

his family's opposition to his projected marriage. The free

association test is useful rather as giving the experienced

psychologist hints to be followed up than as furnishing sure proof of

the contents of the subject's mind.

Controlled Association

There is a controlled association test conducted like this one in free

association, except that the subject is required to respond to each

stimulus word by a word standing in a specified relation to it. To one

series of words he must respond by saying their opposites; to another,

by mentioning a part of each object named; to another series,

consisting of names of countries, he must respond by naming as quickly

as possible the capital of each country named; and there are many

tests of this sort, each dealing with some class of relationships

which, being often observed, are easily handled {382} by a person of

normal intelligence. The intelligent subject makes few errors in such

a test, and responds in very quick time. Indeed, the remarkable fact

is that he takes less time to respond in an easy controlled

association test than in the free association test; which shows that

the "control" acts not simply to limit the response, but also to

_facilitate_ it.

The "control" here is often called by the name of "mental set". It is

a good example of a "reaction tendency". On being told you are to give

opposites, you somehow set or adjust your mental machinery for making

this type of response. The mental set thus thrown into action

facilitates responses of the required type, while inhibiting other

responses that would readily occur in the absence of any directive

tendency. If the word "good" came as a stimulus word in a free

association test, it might easily arouse the responses, "good day",

"good night", "good boy", "good better", and many besides, since all

of these combinations have been frequently used in the past; and the

balance of frequency, recency and intensity might favor any one of

these responses. But when the subject is set for opposites, the

balance of these factors has little force as against the mental set.

The mental set for opposites favors the revival of such combinations

as "new--old", "good--bad", and such others of this class as have been

noted and used in the subject's past experience.

Mental set is a selective factor, a factor of advantage. It does not

supersede the previously formed associations, or work independently of

them, but selects from among them the one which fits the present task.

Does it get in its work after recall has done its part, or before?

Does it wait till recall has brought up a number of responses, and

then pick out the one that fills the bill? No, it often works much too

quickly for that, giving the right response instantly; and

introspection is often perfectly clear that none but the right {383}

response is recalled at all. The selective influence of the mental set

is exerted _before recall_; it facilitates the right recall and

inhibits recall of any but the right response.

In controlled association, as in free association, only one of the

facts previously linked with the stimulus is recalled at a time; but

while in free association the factors of frequency, recency and

intensity of past linkage determine which of the many possible facts

shall be recalled, in controlled association the additional factor of

mental set is present and has a controlling influence in determining

which fact shall be recalled. Thus, in an opposites test, the stimulus

word "good" promptly calls up the pair "good--bad", because the mental

set for opposites gives this response a great advantage over "good

night" and other responses which may have a very strong linkage with

the stimulus word.

The mental set is itself a response to a stimulus. It is an inner

response thrown into activity by some stimulus, such as the stimulus

of being asked to give the opposites of a series of words that are

presently to be shown or spoken. This inner response of getting ready

for the task can be introspectively observed by a person who is new to

this type of test. It may take the form of mentally running over

examples of opposites--or whatever kind of responses are to be called

for--or it may take the form of calling up some image or diagram or

gesture that symbolizes the task. A visual image of the nose on the

face may serve as a symbol of the part-whole relationship, a small

circle inside a larger one may symbolize the relation of an object to

a class of objects, and gesturing first to the right and then to the

left may symbolize the relationship of opposites. But as the subject

grows accustomed to a given task, these conscious symbols fade away,

and nothing remains except a general "feeling of readiness" or of

"knowing what you are {384} about". The mental set remains in force,

however, and is no less efficient for becoming almost unconscious.

Examples of Controlled Association

Dwelling so long on the test for controlled association may have

created the impression that this is a rather artificial and unusual

type of mental performance; but in reality controlled association is a

very representative mental process, and enters very largely into all

forms of mental work. This is true in arithmetical work, for example.

A pair of numbers, such as 8 and 3, has been linked in past experience

with several responses; it means 83, it means 11, it means 5, and it

means 24. But if you are adding, it means 11, and no other response

occurs; if you are multiplying, it means 24, and only that response

occurs. The mental set for multiplying facilitates the responses of

the multiplication table and inhibits those of the addition table,

while the mental set for adding does the reverse. Rapid adding or

multiplying would be impossible without an efficient mental set. Thus

in arithmetic, as in the tests, the mental set is an inner response to

the _task_.

In reading, there is a mental set which is an inner response to the

_context_, and which determines which of the several well-known

meanings of a word shall actually be called to mind when the word is

read. Presented alone, a word may call up any of its meanings,

according to frequency, etc.; but in context it usually brings to mind

just the one meaning that fits the context. The same is true of

conversation.

The objective _situation_ arouses a mental set that controls both

thought and action. The situation of being in church, for example,

determines the meanings that are got from the words heard, and

controls the motor behavior to {385} fit the occasion. The subject,

observing the situation, adjusts himself to it, perhaps without any

conscious effort, and his adjustment facilitates appropriate mental

and motor reactions, while inhibiting others.

A _problem_ arouses a mental set directed towards solution of the

problem. A difficult problem, however, differs from a context or

familiar task or situation in this important respect, that the

appropriate response has not been previously linked with the present

stimulus, so that, in spite of ever so good a mental set, the right

response cannot immediately be recalled. One must _search_ for the

right response. Still, the mental set is useful here, in directing the

search, and keeping it from degenerating into an aimless running

hither and thither. Problem solution is so different a process from

smooth-running controlled association that it deserves separate

treatment, which will be given it a few chapters further on, under the

caption of reasoning.

{386}

EXERCISES

1. Outline the chapter.

2. The rating of images belonging under different senses. Try to

call up the images prescribed below, and rate each image according

to the following scale:

_3. . . . The image is practically the same as a sensation, as bright,

full, incisive, and, in short, possessed of genuine

sensory quality_.

_2. . . . The image has a moderate degree of sensory quality_.

_1. . . . The image has only faint traces of sensory quality_.

_0. . . . No sensory image is called up, though there was a

recall of the fact mentioned_.

Call up visual images of: a friend's face, a sun flower, a white

house among trees, your own signature written in ink.

Call up auditory images of: the sound of your friend's voice, a

familiar song, an automobile horn, the mewing of a cat.

Call up olfactory images of: the odor of coffee, of new-mown hay, of

tar, of cheese.

Call up gustatory images of: sugar, salt, bitter, acid.

Call up cutaneous images of: the feel of velvet, a lump of ice, a

pencil held against the tip of your nose, a pin pricking your

finger.

Call up kinesthetic imagery of: lifting a heavy weight, reaching up

to a high shelf, opening your mouth wide, kicking a ball.

Call up organic imagery of: feeling hungry, feeling thirsty, feeling

nausea, feeling buoyant.

In case of which sense do you get the most lifelike imagery, and in

case of which sense the least. By finding the average rating given

to the images of each sense, you can arrange the senses in order,

from the one in which your imagery rates highest to the one in which

it rates lowest. It may be best to try more cases before reaching a

final decision on this matter.

3. Verbal imagery. When you think of a word, do you have a visual,

auditory, or kinesthetic image of it--or how does it come?

4. In reading, notice how much imagery of objects, persons, scenes,

sounds, etc., occurs spontaneously.

5. Analysis of a revery. Take any object as your starting point,

and let your mind wander from that wherever it will for a minute.

{387} Then review and record the series of thoughts, and try to

discover the linkages between them.

6. Free association experiment. Respond to each one of a list of

disconnected words by saying the first word suggested by it. Use

the following list: city, war, bird, potato, day, ocean, insect,

mountain, tree, roof.

7. Controlled association, (a) Use the same list of stimulus words

as above, but respond to each by a word meaning the _opposite_ or

at least something contrasting, (b) Repeat, naming a _part_ of the

object designated by each of these same words, (c) Repeat again,

naming an _instance_ or variety of each of the objects named. Did

you find wrong responses coming up, or did the mental set exclude

them altogether?

8. Write on a sheet of paper ten pairs of one-place numbers, each

pair in a little column with a line drawn below, as in addition or

multiplication examples. See how long it takes you to _add_, and

again how long it takes to _multiply_ all ten. Which task took the

longer, and why? Did you notice any interference, such as thinking

of a sum when you were "set" for products?

9. Free association test for students of psychology. Respond to

each of the following stimulus words by the first word suggested by

it of a psychological character:

conditioned

objective

gregarious

delayed

correlation

fear

negative

end-brush

mastery

rat

pyramidal

submission

stimulus

semicircular

feeling-tone

substitute

kinesthetic

primary

axon

advantage

tension

synapse

field

blend

autonomic

quotient

rod

retention

limit

fovea

nonsense

apraxia

saturated

higher

thalamus

red-green

paired

organic

complementary

economy

tendency

after

exploration

preparatory

basilar

recency

native

fluctuation

curve

endocrine

dot

perseveration

expressive

Binet

synesthesia

James-Lange

frontal

facilitation

flexion

overlapping

{388}

REFERENCES

On imagery, synesthesia, etc., see Gallon's _Inquiries into Human

Faculty and Its Development_, 1883, pp. 57-112; and for more recent

studies of imagery see G. H. Betts on _The Distribution and Function

of Mental Imagery_, 1909, and Mabel R. Fernald on _The Diagnosis of

Mental Imagery_, 1912.

On the diagnostic use of the association test, an extensive work is

that of C. G. Jung, _Studies in Word-Association_, translated by Eder,

1919.

{389}

CHAPTER XVI

THE LAWS OF ASSOCIATION

AN ATTEMPT TO REDUCE THE LEARNING PROCESS TO ITS ELEMENTS

This is a very serious occasion. What we now have before us is one of

the great outstanding problems of psychology, a problem that has come

down through the ages, with succeeding generations of psychological

thinkers contributing of their best to its solution; and our task is

to attack this problem afresh in the light of modern knowledge of the

facts of learning and memory. We wish to gather up the threads from

the three preceding chapters, which have detailed many facts regarding

learned reactions of all sorts, and see whether we cannot summarize

our accumulated knowledge in the form of a few great laws. We wish

also to relate our laws to what is known of the brain machinery.

The Law of Exercise

Of one law of learning, we are perfectly sure. There is no doubt that

the exercise of a reaction strengthens it, makes it more precise and

more smooth-running, and gives it an advantage over alternative

reactions which have not been exercised. Evidence for these statements

began to appear as soon as we turned the corner into this part of our

subject, and has accumulated ever since. This law is sometimes called

the "law of habit", but might better be called the "law of improvement

of a reaction through exercise", or, more briefly, the "law of

exercise".

{390}

The law of exercise is very broad in its scope, holding good of life

generally and not alone of mental life. Exercise of a muscle develops

the muscle, exercise of a gland develops the gland; and, in the same

way, exercise of a mental reaction strengthens the machinery used in

making that reaction.

Let us restate the law in terms of stimulus and response. _When a

given stimulus arouses a certain response, the linkage between that

stimulus and that response is improved by the exercise so obtained_,

and thereafter the stimulus arouses the response more surely, more

promptly, more strongly than before.

Under the law of exercise belong several _sub-laws_ already familiar

to us.

1. The law of _frequency_ refers to the cumulative effect of repeated

exercise. The practice curve gives a picture of this sub-law, showing

how improvement with repeated exercise of a performance is rapid at

first and tapers off into the physiological limit, beyond which level

more repetition cannot further improve the performance. The

superiority of "spaced study" over unspaced means that exercise is

more effective when rest periods intervene between the periods of

exercise; as this is notoriously true of muscular exercise, it is not

surprising to find it true of mental performances as well.

2. The law of _recency_ refers to the gradual weakening of the

machinery for executing a reaction when no longer exercised; it is the

general biological law of "atrophy through disuse" applied to the

special case of learned reactions. As exercise improves the linkage

between stimulus and response, so disuse allows the linkage to

deteriorate. This law is pictured more completely and quantitatively

in the curve of forgetting.

Really, there are two laws of recency, the one being a {391} law of

retention, the other a law of momentary warming up through exercise.

The law of retention, or of forgetting, is the same as atrophy through

disuse. The warming-up effect, well seen in the muscle which is

sluggish after a long rest but becomes lively and responsive after a

bit of exercise, [Footnote: See p. 73.] appears also in the fact that

a skilled act needs to be done a few times in quick succession before

it reaches its highest efficiency, and in the fact of "primary

memory", the lingering of a sensation or thought for a few moments

after the stimulus that aroused it has ceased. Primary memory is not

strictly memory, since it does not involve the recall of facts that

have dropped out of mind, but just a new emphasis on facts that have

not yet completely dropped out. Warming up is not a phenomenon of

learning, but it is a form of recency, and is responsible for the very

strong "recency value" that is sometimes a help in learning,

[Footnote: See p. 345.] and sometimes a hindrance in recall.

[Footnote: See p. 356.]

3. The law of _intensity_ simply means that vigorous exercise

strengthens a reaction more than weak exercise. This is to be

expected, but the question is, in the case of mental performances, how

to secure vigorous exercise. Well, by active recitation as compared

with passive reception, by close attention, by high level observation.

In active recitation, the memorizer strongly exercises the performance

that he is trying to master, while in reading the lesson over and over

he is giving less intense exercise to the same performance.

The Law of Effect

We come now to a law which has not so accepted a standing as the law

of exercise, and which may perhaps be another sub-law under that

general law. The "law of effect" may, however, be regarded simply as a

generalized statement of {392} the facts of learning by trial and

error. The cat, in learning the trick of escaping from a cage by

turning the door-button, makes and therefore exercises a variety of

reactions; and you might expect, then, in accordance with the law of

exercise, that all of these reactions would be more and more firmly

linked to the cage-situation, instead of the successful reaction

gradually getting the advantage and the unsuccessful being eliminated.

The law of effect, stated as objectively as possible, is simply that

the successful or unsuccessful outcome or _effect_ of a reaction

determines whether it shall become firmly linked with the stimulus, or

detached from the stimulus and thus eliminated. _The linkage of a

response to a stimulus is strengthened when the response is a success,

and weakened when the response is a failure_.

Success here means reaching the goal of an awakened desire or

_reaction-tendency_, and failure means being stopped or hindered from

reaching the goal. Since success is satisfying and failure unpleasant,

the law of effect is often stated in another form: a response that

brings satisfaction is more and more firmly attached to the situation

and reaction-tendency, while a response that brings pain or

dissatisfaction is detached.

The law of effect is a statement of fact, but the question is whether

it is an ultimate fact, or whether it can be explained as a special

case of the law of exercise. Some have suggested that it is but a

special case of the sub-law of frequency; they call attention to the

fact that the successful response must be made at every trial, since

the trial continues till success is attained, whereas no one

unsuccessful response need be made at every trial; therefore in the

long run the successful response must gain the frequency advantage.

But there is a very ready and serious objection to this argument; for

it may and does happen that an unsuccessful response is repeated

several times during a single {393} trial, while the successful

response is never made more than once in a single trial, since success

brings the trial to a close; and thus, as a matter of fact, frequency

often favors the unsuccessful response--which, nevertheless, loses out

in competition with the successful response.

Can the law of effect be interpreted as an instance of the sub-law of

recency? The successful reaction always occurs at the end of a trial,

and is the most recent reaction at the beginning of the next trial.

This recency might have considerable importance if the next trial

began instantly (as in unspaced learning), but can have no importance

when so long as interval as a day is left between trials; for

evidently the recency of twenty-four hours plus ten seconds is not

effectively different from that of an even twenty-four hours. Recency,

then, does not explain the law of effect.

Can it be explained as an instance of the sub-law of intensity? An

animal, or man, who sees success coming as he is making the reaction

that leads directly to success, throws himself unreservedly into this

reaction, in contrast with his somewhat hesitant and exploratory

behavior up to that time. The dammed-up energy of the

reaction-tendency finds a complete outlet into the successful

reaction, and therefore the successful reaction is more intensely

exercised than the unsuccessful. This seems like a pretty good

explanation, though perhaps not a complete explanation.

Limitations of the Law of Exercise

The law of exercise, with all its sub-laws, is certainly fundamental

and universal; it is always in operation whenever anything is learned;

and yet, just by itself, it goes only halfway towards accounting for

learned reactions. For a reaction to be exercised, it must be _made_,

and the law of exercise presupposes that it is made, and does not

attempt to account for its being made in the first place.

{394}

The law of exercise does not cover the formation of new linkages, but

only the strengthening of linkages that are already working. It does

not explain the attachment of a response to some other than its

natural stimulus, nor the combination, of responses into a higher

unit, nor the association of two facts so that one later recalls the

other. We learn by doing, but how can we do anything new so as to

start to learn? We learn by observing combinations of facts, but how

in the first place do we combine the facts in our minds?

How, for example, can we learn to respond to the sight of the person

by saying his name? Evidently, by exercising this linkage of stimulus

and response. But how did we ever make a start in responding thus,

since there is nothing about the person's looks to suggest his name?

The name came to us through the ear, and the face by way of the eye;

and if we repeated the name, that was a response to the auditory

stimulus and not to the visual. How has it come about, then, that we

later respond to the visual stimulus by saying the name?

In short, the more seriously we take the law of exercise, the more we

feel the need of a supplementary law to provide for the first making

of a reaction that then, by virtue of exercise, is strengthened.

This is the problem that occupied the older writers on psychology when

they dealt with "association"; and their solution of the problem was

formulated in the famous "laws of association". The laws of

association were attempts to explain how facts got associated, so that

later one could recall another.

These laws have a long history. From Aristotle, the ancient Greek who

first wrote books on psychology, there came down to modern times four

laws of association. Facts become associated, according to Aristotle,

when they are {395} contiguous (or close together) in space, or when

they are contiguous in time, or when they resemble each other, or when

they contrast with each other. The psychologists of the earlier modern

period, in the eighteenth and first part of the nineteenth centuries,

labored with very good success to reduce these four laws to one

comprehensive law of association. Contiguity in space and in time were

combined into a law of association by _contiguity in experience_,

since evidently mere physical contiguity between two objects could

establish no association between them in any one's mind except as he

experienced them together.

Association by Similarity

Continuing their simplification of the laws of association, these

older psychologists showed that resemblance and contrast belonged

together, since to be similar things must have something in common,

and to be contrasted also two things must have something in common.

You contrast north with south, a circle and a square, an automobile

and a wheelbarrow; but no one thinks of contrasting north with a

circle, south with an automobile, or a square and a wheelbarrow,

though these pairs are more incongruous than the others. Things that

are actually associated as contrasting with each other have something

in common; and therefore association by contrast could be included

under association by similarity. Thus the four laws had been reduced

to two, association by contiguity and association by similarity.

The final step in this reduction was to show that association by

similarity was a special case of association by contiguity. To be

similar, two things must have something in common, and this common

part, being contiguous with the remainder of each of the two things,

establishes an indirect contiguity between the two things, a {396}

sort of contiguity bridge between them. One thing has the parts or

characteristics, A B X Y, and the similar thing has the parts or

characteristics, C D X Y; and thus X Y, when seen in the second thing,

call up A B, with which they are contiguous in the first thing.

A stranger reminds me of my friend because something in the stranger's

face or manner has been met with before in my friend; it has been

contiguous with my friend, and recalls him by virtue of this

contiguity. The stranger, as a whole individual, has never been

contiguous with my friend, but some characteristic of the stranger has

been thus contiguous. In association by similarity, it is not the

whole present object that arouses recall of the similar object, but

some _part_ of the present object. This kind of association is

important in thinking, since it brings together facts from different

past experiences, and thus assembles data that may be applied to a new

problem. If every new object or situation could only be taken as a

whole, it could not remind me of anything previously met; and I should

be like an inexperienced child in the presence of each new problem;

but, taken part by part, the novel situation has been met with before,

and can be handled in the light of past experience.

Exactly what there is in common between two similar faces or other

objects cannot always be clearly made out; but the common

characteristic is there, even if not consciously isolated, and acts as

an effective stimulus to recall.

Association by Contiguity

This reduction of all the laws of association to one great law was no

mean achievement; and the law of association by contiguity in

experience holds good. If one thing recalls another to your mind, you

can be sure that the two {397} have been contiguous in your

experience, either as wholes or piecemeal. For two things to become

associated, they must be experienced together.

Yes, the law holds good, when thus stated--but notice that the

statement is virtually negative. It says, in effect, that two things

do _not_ become associated _unless_ they are contiguous in experience.

If it were turned about to read that two things do become associated

if they are contiguous in experience, it would no longer be a true

law, for the exceptions would then be extremely numerous.

The memory and testimony experiments have brought many exceptions to

light. Show a person twenty pictures in a row, and let him examine

each one in turn so closely that he can later recognize every one of

them; and still he will not have the adjacent pictures so associated

that each one can call up the next in order. To accomplish his last

task, he has to observe the order specifically; it is not enough that

he simply experiences pictures together. Or, again, read to a person

twenty pairs of words, asking him to notice the pairs so that later he

can respond by the second word of any pair when the first word is

given him; and read the list through three or four times, so that he

shall be able to make almost a perfect score in the expected test;

still he will have formed few associations between the contiguous

pairs, and will make a very low score if you ask him to recite the

pairs in order. Many similar experiments have yielded the same general

result--contiguity in experience and still no association.

The law of association by contiguity is unsatisfactory from a modern

standpoint because it treats only of the stimulus, and says nothing

about the response. It states, quite truly, that stimuli must be

contiguous in order that an association between them may be formed,

but it neglects to state that the association, being something in us,

must {398} be formed by our reaction to the stimuli. It is especially

necessary to consider the response because, as we have just seen, the

response is not always made and the association, therefore, not always

formed. Only if the stimuli are contiguous, can the associating

response be aroused, but they do not infallibly arouse it even if they

are contiguous.

The law of contiguity is incomplete, also, because it is not

applicable to the association of two motor acts into a coördinated

higher unit, or of the combination of two primary emotions into a

higher emotional unit.

In a word, the time-honored law of association is no longer

satisfactory because it does not fit into a stimulus-response

psychology. It comes down from a time when the motor side of mental

performances was largely overlooked by psychology, and when the

individual was pictured as being passively "impressed" with the

combinations of facts that were presented to his senses.

The Law of Combination

What we need, then, as an improvement on the old law of association by

contiguity, and as a supplement to the law of exercise, is some law

governing the response to two or more contiguous stimuli. Now we

already have such a law, which we put to some use in studying

attention, [Footnote: See pp. 268-264.] and called the law of

"combination", or of "unitary response to a plurality of stimuli". We

had better fetch that law out again and put it in good repair, and see

whether it is adequate for the job that we now have on hand. In a very

general, abstract form, the law of combination read that "two or more

stimuli may arouse a single joint response". Let us add a single word,

which had not risen above the horizon when we formulated the law

before, and say that {399} _two or more contiguous stimuli may arouse

a single joint response_.

That seems very little to say; can we possibly go far with so simple a

statement? Well, let us see. In saying that two or more stimuli arouse

a single response, we imply that _there is already some rudimentary

linkage between each stimulus and their common response, and that this

linkage is used in arousing the response_. Now bring in our trusty law

of exercise, and we see that the use, or exercise, of such a linkage

may strengthen it to such an extent that, _later, a single one of the

stimuli may arouse the response which was originally aroused by the

whole collection of stimuli_.

Does that promise any better? Probably it requires further discussion

and exemplification before its value can be appreciated. Let us, then,

first discuss it a bit, and then apply it to the explanation of the

chief varieties of learned reaction that have come to our attention.

The law of combination attempts to show how it comes about that a

stimulus, originally unable to arouse a certain response, acquires the

power of arousing it; and the law states that this occurs only when

the originally ineffective stimulus is combined with others which can

and do arouse the response. The ineffective stimulus, being one of a

combination of stimuli which collectively arouse the response,

participates to some slight degree in arousing that response and may

thus become effectively linked with the response.

Notice an assumption underlying the law of combination. Evidently a

stimulus could not take part in arousing a response unless there were

some pre-existing linkage between it and the response. This linkage

may however be extremely loose and feeble, and wholly incapable by

itself of arousing the response. The assumption of pre-existing loose

linkage between almost any stimulus and almost any response is

justified by the facts of playful behavior and trial and error {400}

behavior. In addition to the close reflex connections provided in the

native constitution, and in addition also to the close connections

formed in previous training, there are at any time, and especially in

childhood and youth, a vast number of loose connections. These are too

weak to operate singly, until they have coöperated in producing a

response, and thus been individually strengthened, after which they

may be able singly to produce the response.

The law of combination, then, as applied to learning, includes four points:

(a) A collection of stimuli may work together and arouse a single

response.

(b) This is possible because of pre-existing loose linkage between

the separate stimuli and the response.

(c) When any stimulus, working together with others, helps to arouse

a response, its linkage with that response is strengthened by

exercise.

(d) The linkage may be sufficiently strengthened so that a single

stimulus can arouse the response without help from the other

stimuli that were originally necessary.

Having now abundantly stated and reiterated the law of combination in

the abstract, let us turn to concrete instances of learned reactions,

and see how the law takes care of them. We have already classified a

large share of all the concrete instances under a few main heads, as

substitute stimulus, substitute response, combination (or association)

of stimuli, and combination of responses. We shall presently find it

possible to reduce these four classes to two, since the association of

two objects, by virtue of which one of them later recalls the other,

is a rather complicated case of substitute stimulus, while the

combination of movements into a higher unit is a complicated case of

substitute response.

[Footnote: To distinguish between "substitute stimulus" and

"substitute response" is, in strict logic, like distinguishing

between "inside out" and "outside in." Whenever there is a

substitute stimulus there is also a substitute response, of course,

since this stimulus, in being substituted for another, gets that

other's response in place of its own original response; and in the

same way, you can always find substitute stimulus in any instance of

substitute response; for, in being substituted for another, a

response gets that other's stimulus in place of its own original

stimulus. For all that, the distinction between the two main cases

of learning is of some importance, since sometimes the changed

stimulus, and sometimes the changed response, is the interesting

fact.]

{401}

I. SUBSTITUTE STIMULUS EXPLAINED BY THE LAW OF COMBINATION

Here the response, without being itself essentially changed, becomes

attached to a new stimulus. We distinguish two cases under the general

head of substitute stimulus. In the one case, the substitute stimulus

was originally extraneous, and unnecessary for arousing the response,

while in the other case it was originally necessary as part of a team

of stimuli that aroused the response.

A. Substitute Stimulus Originally Unnecessary for Arousing the

Response

1. Conditioned reflex.

This is the very simplest case belonging under the law of combination.

The dog that responded to the bell by a flow of saliva, after the bell

plus a tasting substance had acted together on him time after time, is

the typical instance; and another good instance is that of the little

child who was "taught" to shrink from a rabbit by the sounding of a

harsh noise along with the showing of the rabbit. [Footnote: See p.

303.] The explanation of all instances of conditioned reflex is the

same. We have an effective stimulus acting, i.e., a stimulus strongly

linked with the response; and we also have acting an ineffective

stimulus, which gets drawn into the same reaction. The effective

stimulus determines what response shall be made, and the other

stimulus finds an outlet {402} into that response, being, as it seems,

attracted towards the activated response, sucked into it. The weak

linkage from the ineffective stimulus to the response, being thus used

and strengthened, later enables this stimulus to arouse the response

single-handed.

This sort of thing is best presented in a diagram. A full line in the

diagram denotes a linkage strong enough to work alone, while a dotted

line denotes a weak linkage. Letters stand for stimuli and responses.

In the diagram for conditioned reflex, A is the original effective

stimulus (the rasping noise in the instance of the child and the

rabbit), and B is the ineffective stimulus (the sight of the rabbit).

R is the shrinking response, linked strongly to the stimulus A and

only weakly to the stimulus B, which has several other linkages fully

as good as the linkage B-R. But A arouses the response R; and R, being

thus activated, draws on B and brings the linkage B-R into use. After

this has occurred a number of times, the linkage B-R has been so

strengthened by repeated exercise that it can operate alone, so that

the rabbit brings the shrinking response even in the absence of A, the

noise.

[Illustration: Fig. 55.--Attachment of the substitute stimulus in the

case of the conditioned reflex.]

At first, the child shrinks from the noise, but, the rabbit being

before his eyes, he incidentally shrinks from the rabbit as well. He

really shrinks in response to all the stimuli acting on him at that

moment. He shrinks from the whole situation. He makes a unitary

response to the whole collection of contiguous stimuli, and thus

exercises the linkage between each stimulus and their joint response.

The {403} linkage between rabbit and shrinking is later strong enough

to work alone. It is a clear case of the law of combination.

2. Learning the names of things.

A child who can imitate simple words that he hears is shown a penny

and the word "penny" is spoken to him. To this combination of stimuli

he responds by saying the word. This is primarily a response to the

auditory stimulus, since the sight of the penny, though it might

probably have aroused some response, and even some vocal response from

the child, had no strong linkage with this particular vocal response.

But the auditory stimulus determined the response, and attracted the

visual stimulus into this particular channel of saying "penny". The

linkage from the sight of the penny to the saying of this word being

thus strengthened by exercise, the seen penny later gives the right

vocal response, without any auditory stimulus to assist.

[Illustration: Fig. 56.--Linkage of a name to an object. The diagram

is arranged to illustrate the formation of a linkage from the sight

of the object to saying its name. A very similar diagram would

illustrate the linkage from the name to the thought or image of the

object. The acquiring of mental images seems to be essentially the

same process as the acquiring of conditioned reflexes, and of names.

(Figure text: object seen, various possible responses, name heard,

name spoken)]

{404}

B. Substitute Stimulus Originally an Essential Member Of A Team of

Stimuli That Aroused the Response

1. Observed grouping or relationship.

"Learning by observation" is a very important human accomplishment,

and we found many evidences of its importance in our study of the

process of memorizing. The facts observed, which assist memory so

greatly, are usually relations or groups.

[Illustration: Fig. 57.--The formation of an association between two

objects by observing their grouping or relationship. (Figure text:

response of observing the Group A B, thought of Group A B)]

Evidently the observation of a group of things is a response to a

collection of stimuli, and could not originally be aroused by any one

of the stimuli alone. The same is true of observing a relationship;

the observation is a response to two things taken together, and not,

originally, to either of the two things taken alone. In spite of this,

a single one of the things may later call to mind the relationship, or

the group; that is, it arouses the response originally made to the

pair or group of stimuli. The single stimulus has been substituted for

the team that originally aroused the response. Its linkage with the

response has been so strengthened by exercise as to operate

effectively without assistance.

For example, in learning pairs of words in a "paired {405} associates

experiment", [Footnote: See p. 336.] the subject is apt to find some

relation between the words forming a pair, even though they are

supposed to be "unrelated words". When he has thus learned the pair,

either of the words in it will recall the observed relation and the

other word of the pair. Sometimes, after a long interval especially,

the relation is recalled without the other word. One subject fixed the

pair, "windy--occupy", by thinking of a sailor occupying a windy perch

up in the ropes. Some weeks later, on being given the word "windy", he

recalled the sailor on the perch, but could not get the word "occupy".

That is, he made the same response to "windy" that he had originally

made to "windy--occupy", but did not get the response completely

enough to give the second word.

In the typical cases of _association by contiguity_ when one object

reminds us of another that was formerly experienced together with it,

the law of combination comes in as just described. The two objects

were observed to be grouped or related in some way, or some such

unitary response was made to the two objects taken together, and this

response became so linked to each of the objects that later a single

one of them arouses this unitary response and recalls the other

object. In the free association test, [Footnote: See p. 380.] the

stimulus word "dimple" calls up the previously made response of seeing

a dimple in a cheek, and so leads to the word "cheek". In a controlled

association test, where opposites are required, the stimulus word

"mythical" arouses the previously made observation of the antithesis

of mythical and historical, and so leads to the motor response of

saying the latter word.