The Analysis of Mind, Bertrand Russell [best desktop ebook reader .txt] 📗

France?” we answer “Paris,” because of

past experience; the past experience is as essential as the

present question in the causation of our response. Thus all our

habitual knowledge consists of acquired habits, and comes under

the head of mnemic phenomena.

 

(b) IMAGES.—I shall have much to say about images in a later

lecture; for the present I am merely concerned with them in so

far as they are “copies” of past sensations. When you hear New

York spoken of, some image probably comes into your mind, either

of the place itself (if you have been there), or of some picture

of it (if you have not). The image is due to your past

experience, as well as to the present stimulus of the words “New

York.” Similarly, the images you have in dreams are all dependent

upon your past experience, as well as upon the present stimulus

to dreaming. It is generally believed that all images, in their

simpler parts, are copies of sensations; if so, their mnemic

character is evident. This is important, not only on its own

account, but also because, as we shall see later, images play an

essential part in what is called “thinking.”

 

(c) ASSOCIATION.—The broad fact of association, on the mental

side, is that when we experience something which we have

experienced before, it tends to call up the context of the former

experience. The smell of peat-smoke recalling a former scene is

an instance which we discussed a moment ago. This is obviously a

mnemic phenomenon. There is also a more purely physical

association, which is indistinguishable from physical habit. This

is the kind studied by Mr. Thorndike in animals, where a certain

stimulus is associated with a certain act. This is the sort which

is taught to soldiers in drilling, for example. In such a case

there need not be anything mental, but merely a habit of the

body. There is no essential distinction between association and

habit, and the observations which we made concerning habit as a

mnemic phenomenon are equally applicable to association.

 

(d) NONSENSATIONAL ELEMENTS IN PERCEPTION.—When we perceive any

object of a familiar kind, much of what appears subjectively to

be immediately given is really derived from past experience. When

we see an object, say a penny, we seem to be aware of its “real”

shape we have the impression of something circular, not of

something elliptical. In learning to draw, it is necessary to

acquire the art of representing things according to the

sensation, not according to the perception. And the visual

appearance is filled out with feeling of what the object would be

like to touch, and so on. This filling out and supplying of the

“real” shape and so on consists of the most usual correlates of

the sensational core in our perception. It may happen that, in

the particular case, the real correlates are unusual; for

example, if what we are seeing is a carpet made to look like

tiles. If so, the nonsensational part of our perception will be

illusory, i.e. it will supply qualities which the object in

question does not in fact have. But as a rule objects do have the

qualities added by perception, which is to be expected, since

experience of what is usual is the cause of the addition. If our

experience had been different, we should not fill out sensation

in the same way, except in so far as the filling out is

instinctive, not acquired. It would seem that, in man, all that

makes up space perception, including the correlation of sight and

touch and so on, is almost entirely acquired. In that case there

is a large mnemic element in all the common perceptions by means

of which we handle common objects. And, to take another kind of

instance, imagine what our astonishment would be if we were to

hear a cat bark or a dog mew. This emotion would be dependent

upon past experience, and would therefore be a mnemic phenomenon

according to the definition.

 

(e) MEMORY AS KNOWLEDGE.—The kind of memory of which I am now

speaking is definite knowledge of some past event in one’s own

experience. From time to time we remember things that have

happened to us, because something in the present reminds us of

them. Exactly the same present fact would not call up the same

memory if our past experience had been different. Thus our

remembering is caused by—

 

(1) The present stimulus,

 

(2) The past occurrence.

 

It is therefore a mnemic phenomenon according to our definition.

A definition of “mnemic phenomena” which did not include memory

would, of course, be a bad one. The point of the definition is

not that it includes memory, but that it includes it as one of a

class of phenomena which embrace all that is characteristic in

the subject matter of psychology.

 

(f) EXPERIENCE.—The word “experience” is often used very

vaguely. James, as we saw, uses it to cover the whole primal

stuff of the world, but this usage seems objection able, since,

in a purely physical world, things would happen without there

being any experience. It is only mnemic phenomena that embody

experience. We may say that an animal “experiences” an occurrence

when this occurrence modifies the animal’s subsequent behaviour,

i.e. when it is the mnemic portion of the cause of future

occurrences in the animal’s life. The burnt child that fears the

fire has “experienced” the fire, whereas a stick that has been

thrown on and taken off again has not “experienced” anything,

since it offers no more resistance than before to being thrown

on. The essence of “experience” is the modification of behaviour

produced by what is experienced. We might, in fact, define one

chain of experience, or one biography, as a series of occurrences

linked by mnemic causation. I think it is this characteristic,

more than any other, that distinguishes sciences dealing with

living organisms from physics.

 

The best writer on mnemic phenomena known to me is Richard Semon,

the fundamental part of whose theory I shall endeavour to

summarize before going further:

 

When an organism, either animal or plant, is subjected to a

stimulus, producing in it some state of excitement, the removal

of the stimulus allows it to return to a condition of

equilibrium. But the new state of equilibrium is different from

the old, as may be seen by the changed capacity for reaction. The

state of equilibrium before the stimulus may be called the

“primary indifference-state”; that after the cessation of the

stimulus, the “secondary indifference-state.” We define the

“engraphic effect” of a stimulus as the effect in making a

difference between the primary and secondary indifference-states,

and this difference itself we define as the “engram” due to the

stimulus. “Mnemic phenomena” are defined as those due to engrams;

in animals, they are specially associated with the nervous

system, but not exclusively, even in man.

 

When two stimuli occur together, one of them, occurring

afterwards, may call out the reaction for the other also. We call

this an “ekphoric influence,” and stimuli having this character

are called “ekphoric stimuli.” In such a case we call the engrams

of the two stimuli “associated.” All simultaneously generated

engrams are associated; there is also association of successively

aroused engrams, though this is reducible to simultaneous

association. In fact, it is not an isolated stimulus that leaves

an engram, but the totality of the stimuli at any moment;

consequently any portion of this totality tends, if it recurs, to

arouse the whole reaction which was aroused before. Semon holds

that engrams can be inherited, and that an animal’s innate habits

may be due to the experience of its ancestors; on this subject he

refers to Samuel Butler.

 

Semon formulates two “mnemic principles.” The first, or “Law of

Engraphy,” is as follows: “All simultaneous excitements in an

organism form a connected simultaneous excitement-complex, which

as such works engraphically, i.e. leaves behind a connected

engram-complex, which in so far forms a whole” (“Die mnemischen

Empfindungen,” p. 146). The second mnemic principle, or “Law of

Ekphory,” is as follows: “The partial return of the energetic

situation which formerly worked engraphically operates

ekphorically on a simultaneous engram-complex” (ib., p. 173).

These two laws together represent in part a hypothesis (the

engram), and in part an observable fact. The observable fact is

that, when a certain complex of stimuli has originally caused a

certain complex of reactions, the recurrence of part of the

stimuli tends to cause the recurrence of the whole of the

reactions.

 

Semon’s applications of his fundamental ideas in various

directions are interesting and ingenious. Some of them will

concern us later, but for the present it is the fundamental

character of mnemic phenomena that is in question.

 

Concerning the nature of an engram, Semon confesses that at

present it is impossible to say more than that it must consist in

some material alteration in the body of the organism (“Die

mnemischen Empfindungen,” p. 376). It is, in fact, hypothetical,

invoked for theoretical uses, and not an outcome of direct

observation. No doubt physiology, especially the disturbances of

memory through lesions in the brain, affords grounds for this

hypothesis; nevertheless it does remain a hypothesis, the

validity of which will be discussed at the end of this lecture.

 

I am inclined to think that, in the present state of physiology,

the introduction of the engram does not serve to simplify the

account of mnemic phenomena. We can, I think, formulate the known

laws of such phenomena in terms, wholly, of observable facts, by

recognizing provisionally what we may call “mnemic causation.” By

this I mean that kind of causation of which I spoke at the

beginning of this lecture, that kind, namely, in which the

proximate cause consists not merely of a present event, but of

this together with a past event. I do not wish to urge that this

form of causation is ultimate, but that, in the present state of

our knowledge, it affords a simplification, and enables us to

state laws of behaviour in less hypothetical terms than we should

otherwise have to employ.

 

The clearest instance of what I mean is recollection of a past

event. What we observe is that certain present stimuli lead us to

recollect certain occurrences, but that at times when we are not

recollecting them, there is nothing discoverable in our minds

that could be called memory of them. Memories, as mental facts,

arise from time to time, but do not, so far as we can see, exist

in any shape while they are “latent.” In fact, when we say that

they are “latent,” we mean merely that they will exist under

certain circumstances. If, then, there is to be some standing

difference between the person who can remember a certain fact and

the person who cannot, that standing difference must be, not in

anything mental, but in the brain. It is quite probable that

there is such a difference in the brain, but its nature is

unknown and it remains hypothetical. Everything that has, so far,

been made matter of observation as regards this question can be

put together in the statement: When a certain complex of

sensations has occurred to a man, the recurrence of part of the

complex tends to arouse the recollection of the whole. In like

manner, we can collect all mnemic phenomena in living organisms

under a single law, which contains what is hitherto verifiable in

Semon’s two laws. This single law is:

 

IF A COMPLEX STIMULUS A HAS CAUSED A COMPLEX REACTION B IN AN

ORGANISM, THE OCCURRENCE OF A PART OF A ON A FUTURE OCCASION

TENDS TO CAUSE THE WHOLE REACTION B.

 

This law would need to be supplemented by some account of the

influence of frequency, and so on; but it seems to contain the

essential characteristic of