The Nature Of Memory

Now that you come to think of it, you can recall perfectly well that

Columbus discovered America in 1492; that your house is painted white;

that it rained a week ago today. But where were these once-known facts,

now remembered so easily, while they were out of your mind? Where did

they stay while you were not thinking of them? The common answer is,

Stored away in my memory. Yet no one believes that the memory is a

ware ouse of facts which we pack away there when we for a time have no

use for them, as we store away our old furniture.



WHAT IS RETAINED.--The truth is that the simple question I asked you is

by no means an easy one, and I will answer it myself by asking you an

easier one: As we sit with the sunlight streaming into our room, where

is the darkness which filled it last night? And where will all this

light be at midnight tonight? Answer these questions, and the ones I

asked about your remembered facts will be answered. While it is true

that, regardless of the conditions in our little room, darkness still

exists wherever there is no light, and light still exists wherever there

is no darkness, yet for this particular room there is no darkness when

the sun shines in, and there is no light when the room is filled with

darkness. So in the case of a remembered fact. Although the fact that

Columbus discovered America some four hundred years ago, that your house

is of a white color, that it rained a week ago today, exists as a fact

regardless of whether your minds think of these things at all, yet the

truth remains as before: for the particular mind which remembers these

things, the facts did not exist while they were out of the mind.



It is not the remembered fact which is retained, BUT THE POWER TO

REPRODUCE THE FACT WHEN WE REQUIRE IT.



THE PHYSICAL BASIS OF MEMORY.--The power to reproduce a once-known fact

depends ultimately on the brain. This is not hard to understand if we go

back a little and consider that brain activity was concerned in every

perception we have ever had, and in every fact we have ever known.

Indeed, it was through a certain neural activity of the cortex that you

were able originally to know that Columbus discovered America, that your

house is white, and that it rained on a day in the past. Without this

cortical activity, these facts would have existed just as truly, but

you would never have known them. Without this neural activity in the

brain there is no consciousness, and to it we must look for the

recurrence in consciousness of remembered facts, as well as for those

which appear for the first time.



HOW WE REMEMBER.--Now, if we are to have a once-known fact repeated in

consciousness, or in other words remembered, what we must do on the

physiological side is to provide for a repetition of the neural activity

which was at first responsible for the fact's appearing in

consciousness. The mental accompaniment of the repeated activity is the

memory. Thus, as memory is the approximate repetition of

once-experienced mental states or facts, together with the recognition

of their belonging to our past, so it is accomplished by an approximate

repetition of the once-performed neural process in the cortex which

originally accompanied these states or facts.



The part played by the brain in memory makes it easy to understand why

we find it so impossible to memorize or to recall when the brain is

fatigued from long hours of work or lack of sleep. It also explains the

derangement in memory that often comes from an injury to the brain, or

from the toxins of alcohol, drugs or disease.



DEPENDENCE OF MEMORY ON BRAIN QUALITY.--Differences in memory ability,

while depending in part on the training memory receives, rest ultimately

on the memory-quality of the brain. James tells us that four distinct

types of brains may be distinguished, and he describes them as follows:



Brains that are:



(1) Like marble to receive and like marble to retain.

(2) Like wax to receive and like wax to retain.

(3) Like marble to receive and like wax to retain.

(4) Like wax to receive and like marble to retain.



The first type gives us those who memorize slowly and with much heroic

effort, but who keep well what they have committed. The second type

represents the ones who learn in a flash, who can cram up a lesson in a

few minutes, but who forget as easily and as quickly as they learn. The

third type characterizes the unfortunates who must labor hard and long

for what they memorize, only to see it quickly slipping from their

grasp. The fourth type is a rare boon to its possessor, enabling him

easily to stock his memory with valuable material, which is readily

available to him upon demand.



The particular type of brain we possess is given us through heredity,

and we can do little or nothing to change the type. Whatever our type of

brain, however, we can do much to improve our memory by obeying the laws

upon which all good memory depends.