An Introduction to Comparative Psychology
Chapter 7: Memory in Animals
C. Lloyd Morgan
A VERY short chapter will suffice for the consideration of memory as we infer it to occur in animals. In the first place we may notice that the existence of memory is implied in the association of ideas: or rather in the occurrence of ideas at all. For ideas are representations due, in the main, to secondary suggestion. But a representation is a reinstatement as an idea of that which has been presented as an impression ; and such reinstatement constitutes, as we have seen, one aspect of the phenomena of memory. If, therefore, animals have ideas at all-and if they have not we need not attempt to carry any further our investigations into zoological psychology-they must have memory, and there must be in them, as in us, some anatomical and physiological basis for what is popularly termed the retention of ideas.
Observation, moreover, shows that some animals have remarkably tenacious memories. The chick, which having once tasted the poison of a hive-bee avoided again taking a bee into its bill, showed memory not inferior to that of the child which having once been burnt avoids for the future contact with fire. When I had taken some of my chicks to the yard whence I had obtained the eggs, and had made such arrangements as seemed feasible for their being absorbed into a brood of about the same age and standing, I returned after two days to see how they fared under these new conditions of life. One of them was some little distance from the hen, and when I bent down with out-
(118) stretched hand the little thing ran to me and leaped upon my palm, scratching at it in the expectation of grain. I do not say that it remembered me, but it certainly remembered a particular action of mine to which it had grown accustomed.
When I was at the Cape I used to take my two dogs up the Devil's Peak, an outlying point of Table Mountain. There were several places at which it was necessary that I should lift them from ledge to ledge since they could not scramble up by themselves. After the first ascent they always remembered these places and waited patiently to be lifted up. On one of our first ascents one of them put up a young coney and they both gave chase. Subsequently, they always hurried on to this spot, and though they never saw another coney there, reiterated disappointment did not efface the memory of that first chase, or so it seemed. I think the last time I took them up must have been about three and a half years after the coney-hunt : so long had the memory endured and the association remained uneffaced.
Every one probably remembers the instance recorded by Darwin, whose dog recognised him on his return from his five years' voyage round the world in the " Beagle." Sir George Davis (1650) is said to have been recognised by a lion which he bad brought up as a whelp, and parted with three years before. And Bingley records another case when a lion showed indubitable signs of remembering a man who had been his keeper more than seven years before. These cases may be apocryphal, though I do not know that there are valid grounds for doubting them. In any case instances of memory in animals might be multiplied almost indefinitely; and any reader who has had opportunities of observing animals will be able, without difficulty, to supply additional instances from his own observation.
Those who have had some experience in training domes-
(119) -ticated animals will also be well aware that animals show a good deal of variation both in the rapidity with which they form new associations -- that is to say, the frequency of repetition necessary to establish an association-and in the retention of the association when formed. Sonic dogs seem, to learn rapidly, but soon forget the tricks one has taught them; others take longer to learn and seem to require that the association should be many times repeated before it begins to show signs of establishment: but when once the trick has been learnt they never forget it. I was informed by one who had some experience in training dogs for circus performances that those which were slow in acquisition, were by far the more valuable for his purposes; and that very rarely did he find a dog that was both rapid in acquiring a trick and always reliable in its performance. But I am not sure that all trainers would concur in this opinion. All would, however, agree that dogs, even of the same breed, and in the same litter, vary much in powers of memory.
The memory of animals must, I think, be entirely of the desultory type. Systematic memory involves, I conceive, powers beyond their reach. Whether this is so or not, however, depends upon the answer we give to the question to be discussed in a future chapter-Do animals perceive relations ? I do not propose here to anticipate that discussion. It is sufficient to point out that systematic memory is based on the perception of relations. The associations formed are those by similarity of perceived relationship. A new fact is remembered not in virtue of its association with other facts or experiences by contiguity or by mere resemblance, but because it is seen to have a definite bearing upon other facts, to) have recognisable connection with other experiences, to fit into a particular place in a definitely organized scheme, to have meaning in reference to a system of knowledge. Now knowledge, properly so called, is something very different from experience; and
(120) while association by contiguity suffices for and is the groundwork and foundation of sense-experience and the intelligence based thereon, association by similarity of perceived relationship is necessary to form the foundation of -knowledge, and of all rational explanation of phenomena. Desultory memory suffices for sense-experience, and intelligence; systematic memory comes on the scene with the advent of knowledge and reason. Whether animals have knowledge depends upon whether they are able to perceive relations as such. If they have knowledge they may possess that type of memory which we call systematic-a type which arises out of and ministers to knowledge. But if they have, with all their wide range of practical sense- experience, no knowledge properly so called, then is their memory entirely of the desultory type.
Another question-whether the memory of animals may carry with it localization in time-again depends upon whether they can perceive time-relations as such. The discussion of time-localization given in the last chapter brought out the fact that this process-which we saw to be additional to, and no necessary factor in the process of reinstatement in memory-involves the location of the event, or experience in question with. reference to, that is in relation to, other events in the time series. Is there any evidence that animals can thus localize events in time ? Or let us put the question in another form : Can the phenomena of memory in animals, so far as we can observe and infer, be explained in terms of reinstatement, or must we infer a further process of time-localization ? If they can be explained in terms of mere reinstatement, we are bound by the canon discussed at the close of the third chapter not to assume any higher process. For we saw that in no. case is an animal activity to be interpreted as the outcome of the exercise of a higher psychical faculty, if it can be fairly interpreted as the outcome of the existence of one which stands lower in the psychological scale.
Let us take a typical case of memory in an animal. Captain Shipp gave an elephant a sandwich of cayenne pepper. He then waited for six weeks before again visiting the animal, and when he went into the stable began to fondle the elephant, as he had previously been accustomed to do. Watching his opportunity, the animal filled his trunk with water, and drenched the captain from head to foot. Now in such a case of definite memory of a particular occurrence, we are apt to suppose that the original experience is clearly localized, both in place and time. But a little consideration will show that this is not in the least necessary. All that the facts warrant us in concluding is that the sight of the captain gave rise, by association, to a reinstatement of a previous occurrence. So long as the association had not faded from memory, it mattered not whether it was six weeks, six days, or six months ago; and there is no reason for supposing that the elephant in such a case localized the event in time, in even the most rudimentary way.
Animals seem however to show a sense of the lapse of time. A gentleman with. whom I stayed at the Tijuca, near Rio de Janeiro, bad a monkey (Cebus sp.), which was fed regularly at a certain time every evening. The animal was aware to within a few minutes when the time for his meal had arrived, and began to clamour by hammering on his board if the food was not brought punctually. This it may be said shows a pretty definite localization of time, for the monkey must have remembered that his meal was always brought at such a time. But surely the facts can be quite satisfactorily explained by the, association of certain regularly recurring internal states with the regular satisfaction of hunger. And my friend told me that when the monkey was sick, he did not clamour for food; but that when he was recovering, he clamoured before the usual time. I think that many cases of the apparent sense of
(122) the lapse of time may be explained as the result of the orderly recurrence of rhythmic physiological processes, involving the reinstatement of psychological states. Other cases like that of the dog that "knows perfectly well when Sunday comes round" are commonly due to reinstatement through the channels of external sense. Everyone who has closely watched animals knows how keenly they sense what Dr Stout terms the practical meaning of trivial occurrences which affect their daily life.
What then may we fairly infer from the facts given in their behaviour as to the nature of memory in animals? In the first place, the facts of association seem to warrant the conclusion, which is almost if not quite universally accepted, that there is reinstatement of psychical states. But, as Dr Thorndike has contended, such reinstatement does not necessarily involve any of that recognition -process which he regards as essential to memory. If, however,- we accept the general proposition that there are in animals mental processes which we may attempt to interpret,, it is difficult to believe that my dogs did not in any -sense recognize the locality on Table Mountain where they had previously put up a coney, or that the elephant did not, recognize Captain Shipp, who had, through cayenne pepper, acquired a new " meaning." May we not infer' from the facts which common observation affords, that reinstatement in such cases carries with it, as reinstatement, at least such marginal fringe of familiarity as is involved in recurrence within the experience of the same individual ? There may be no conception of the self as the subject of past experience
(123) for the conception of self is the result of much analysis and re-synthesis of experience; but there may none the less be a quite unmistakable sense of reinstatement, as contrasted with a new and unfamiliar happening, which can only be expressed in some such phrase as "been there before." When the young chick which has had experience of nauseous cinnabar caterpillars sees one of these black and yellow objects which has thus acquired meaning, it has presumably this " seen it before " consciousness. In popular speech we should say without hesitation that the chick " recognizes " the caterpillar and that such recognition i's what leads to avoidance. It is indeed recognition within the field of naive sense-experience. It is not intellectual recognition, like that of the naturalist, who recognizes it as the larva of Euchelia jacoboeoe. It is a mere "seen it before" experience suffused with practical meaning; not a "know its relationships "experience, with significance for a system of knowledge.
But the "seen it before" experience probably carries with it, at any rate in the higher animals, a pretty accurate and serviceable representation of the situation previously - lived through. For my dogs a particular locality on Table Mountain was suffused with meaning, and suggested a coney-hunt. The original situation was, we may presume, revived in memory with a sense of past experience. But it may be asked, does not this sense of past experience involve that localization in time which has been denied to the animal? Surely not. Suppose that, as I walk down the street, I see a man whom I recognize as one that I have previously seen. I may picture the situation. I saw him on the station platform in the Metropolitan railway. When it was and at what station I do not remember. Nor do I trouble to recollect unless there be some end to be gained by doing so. Localization in space and time is a distinct, process nowise involved in the picturing of a situation which has occurred in my past experience. Now with regard to anything like definite and systematic localization in time, it is difficult to see of what practical service it would be to animals, living, as they do, so essentially in and for the present enjoyment of the passing moment. What practical advantage would it have been to my dogs
(124) to have any knowledge of when the coney-hunt took place? That it had taken place, and that the situation was a good one, sufficed for the needs of their simple life.
We may conclude then that the memory of animals involves the revival of past situations, involves such elementary form of recognition as is implied in the growth of experience, involves a suffusion of meaning for the practical purposes of their sensory existence, but does not involve any definite assignment of events to their place in a temporal, spacial, or logical system independent of individual experience and possessing universal validity.
And here it will be well to leave these questions, until such time as we have occasion to reconsider them in the light of our discussion of the perception of relations. I will only ask the reader in the meanwhile to be good enough to credit me with an unbiassed (sic) desire to interpret the phenomena of animal psychology without exaggeration, either in the direction of excess or defect of mental power and differentiation. As an evolutionist who believes that the whole range of the mental faculties have been developed by natural processes, the tendency of my bias would assuredly not be in the direction of setting a gulf between the faculties of animals and the faculties of man. My sole aim is to endeavour to reach by legitimate process of scientific induction the most probable interpretation of zoological psychology, and by comparing this with the psychology of man to ascertain by what steps the lower faculties of animals may have passed by natural process of development into the higher faculties of man.