The Nature Of Association

We may define association, then, as the tendency among our thoughts to

form such a system of bonds with each other that the objects of

consciousness are vitally connected both (1) as they exist at any given

moment, and (2) as they occur in succession in the mental stream.



THE NEURAL BASIS OF ASSOCIATION.--The association of thoughts--ideas,

images, memory--or of a situation with its response, rests primarily on
br /> a neural basis. Association is the result of habit working in neurone

groups. Its fundamental law is stated by James as follows: When two

elementary brain-processes have been active together or in immediate

succession, one of them, on recurring, tends to propagate its excitement

into the other. This is but a technical statement of the simple fact

that nerve currents flow most easily over the neurone connections that

they have already used.



It is hard to teach an old dog new tricks, because the old tricks employ

familiar, much-used neural paths, while new tricks require the

connecting up of groups of neurones not in the habit of working

together; and the flow of nerve energy is more easily accomplished in

the neurones accustomed to working together. One who learns to speak a

foreign language late in life never attains the facility and ease that

might have been reached at an earlier age. This is because the neural

paths for speech are already set for his mother-tongue, and, with the

lessened plasticity of age, the new paths are hard to establish.



The connections between the various brain areas, or groups of neurones,

are, as we have seen in an earlier chapter, accomplished by means of

association fibers. This function requires millions of neurones, which

unite every part of the cortex with every other part, thus making it

possible for a neural activity going on in any particular center to

extend to any other center whatsoever. In the relatively unripe brain of

the child, the association fibers have not yet set up most of their

connections. The age at which memory begins is determined chiefly by

the development of a sufficient number of association fibers to bring

about recall. The more complex reasoning, which requires many different

associative connections, is impossible prior to the existence of

adequate neural development. It is this fact that makes it futile to

attempt to teach young children the more complicated processes of

arithmetic, grammar, or other subjects. They are not yet equipped with

the requisite brain machinery to grasp the necessary associations.




stands for the visual, A for the auditory, G for the gustatory, M for

the motor, and T for the thought and feeling centers of the cortex.]



ASSOCIATION THE BASIS OF MEMORY.--Without the machinery and processes of

association we could have no memory. Let us see in a simple illustration

how association works in recall. Suppose you are passing an orchard and

see a tree loaded with tempting apples. You hesitate, then climb the

fence, pick an apple and eat it, hearing the owner's dog bark as you

leave the place. The accompanying diagram will illustrate roughly the

centers of the cortex which were involved in the act, and the

association fibers which connect them. (See Fig. 18.) Now let us see

how you may afterward remember the circumstance through association. Let

us suppose that a week later you are seated at your dining table, and

that you begin to eat an apple whose flavor reminds you of the one which

you plucked from the tree. From this start how may the entire

circumstance be recalled? Remember that the cortical centers connected

with the sight of the apple tree, with our thoughts about it, with our

movements in getting the apple, and with hearing the dog bark, were all

active together with the taste center, and hence tend to be thrown into

activity again from its activity. It is easy to see that we may (1) get

a visual image of the apple tree and its fruit from a current over the

gustatory-visual association fibers; (2) the thoughts, emotions, or

deliberations which we had on the former occasion may again recur to us

from a current over the gustatory-thought neurones; (3) we may get an

image of our movements in climbing the fence and picking the apple from

a current over the gustatory-motor fibers; or (4) we may get an auditory

image of the barking of the dog from a current over the

gustatory-auditory fibers. Indeed, we are sure to get some one or more

of these unless the paths are blocked in some way, or our attention

leads off in some other direction.



FACTORS DETERMINING DIRECTION OF RECALL.--Which of these we get first,

which of the images the taste percept calls to take its place as it

drops out of consciousness, will depend, other things being equal, on

which center was most keenly active in the original situation, and is at

the moment most permeable. If, at the time we were eating the stolen

fruit, our thoughts were keenly self-accusing for taking the apples

without permission, then the current will probably discharge through

the path gustatory-thought, and we shall recall these thoughts and their

accompanying feelings. But if it chances that the barking of the dog

frightened us badly, then more likely the discharge from the taste

center will be along the path gustatory-auditory, and we shall get the

auditory image of the dog's barking, which in turn may call up a visual

image of his savage appearance over the auditory-visual fibers. It is

clear, however, that, given any one of the elements of the entire

situation back, the rest are potentially possible to us, and any one may

serve as a cue to call up all the rest. Whether, given the starting

point, we get them all, depends solely on whether the paths are

sufficiently open between them for the current to discharge between

them, granting that the first experience made sufficient impression to

be retained.



Since this simple illustration may be made infinitely complex by means

of the millions of fibers which connect every center in the cortex with

every other center, and since, in passing from one experience to another

in the round of our daily activities, these various areas are all

involved in an endless chain of activities so intimately related that

each one can finally lead to all the others, we have here the machinery

both of retention and of recall--the mechanism by which our past may be

made to serve the present through being reproduced in the form of memory

images or ideas. Through this machinery we are unable to escape our

past, whether it be good or bad; for both the good and the bad alike are

brought back to us through its operations.



When the repetition of a series of acts has rendered habit secure, the

association is relatively certain. If I recite to you A-B-C-D, your

thought at once runs on to E, F, G. If I repeat, Tell me not in

mournful numbers, association leads you to follow with Life is but an

empty dream. Your neurone groups are accustomed to act in this way, so

the sequence follows. Memorizing anything from the multiplication table

to the most beautiful gems of poetic fervor consists, therefore, in the

setting up of the right associative connections in the brain.



ASSOCIATION IN THINKING.--All thinking proceeds by the discovery or

recognition of relations between the terms or objects of our thought.

The science of mathematics rests on the relations found to exist between

numbers and quantities. The principles and laws of natural science are

based on the relations established among the different forms of matter

and the energy that operates in this field. So also in the realm of

history, art, ethics, or any other field of human experience. Each fact

or event must be linked to other facts or events before it possesses

significance. Association therefore lies at the foundation of all

thinking, whether that of the original thinker who is creating our

sciences, planning and executing the events of history, evolving a

system of ethics, or whether one is only learning these fields as they

already exist by means of study. Other things being equal, he is the

best thinker who has his knowledge related part to part so that the

whole forms a unified and usable system.



ASSOCIATION AND ACTION.--Association plays an equally important part in

all our motor responses, the acts by which we carry on our daily lives,

do our work and our play, or whatever else may be necessary in meeting

and adapting ourselves to our environment. Some sensations are often

repeated, and demand practically the same response each time. In such

cases the associations soon become fixed, and the response certain and

automatic. For example, we sit at the table, and the response of eating

follows, with all its complex acts, as a matter of course. We lie down

in bed, and the response of sleep comes. We take our place at the piano,

and our fingers produce the accustomed music.



It is of course obvious that the influence of association extends to

moral action as well. In general, our conduct follows the trend of

established associations. We are likely to do in great moral crises

about as we are in the habit of doing in small ones.