Chapter VI: Laws and Hypotheses for Behavior (2)

Assuming as typical this same limited case of response to an annoying situation, so that success consists simply in replacing the situation by another, Stevenson Smith reduces the learning-process to the law of exercise alone. He argues that,—

“For instance, let an organism at birth be capable of giving N reactions (a, b, c, ... N) to a definite stimulus S and let only one of these reactions be appropriate. If only one reaction can be given at a time and if the one given is determined by the state of the organism at the time S is received, there is one chance in N that it is the appropriate reaction. When the appropriate reaction is finally given, the other reactions are not called into play, S may cease to act, but until the appropriate reaction is given let the organism be such that it runs through the gamut of the others until the appropriate reaction is brought about. As there are N possible reactions, the chances are that the appropriate reaction will be given before all N are performed. At the next appearance of the stimulus, which we may call S₂, those reactions which were in the last case performed, are, through habit, more likely to be again brought about than those which were not performed. Let _u_ stand for the unperformed reactions. Then we have N - _u_ probable reactions to S₂. Habit rendering the previously most performed reactions the most probable throughout we should expect to find the appropriate reaction in response to

S₁ contained in N.
S₂ contained in N - _u₁_.
S₃ contained in N - _u₁_ - _u₂_.
...
S_ₙ_ contained in N - _nu_, which approaches _one_ as a limit.

Thus the appropriate reaction would be fixed through the laws of chance and habit. This law of habit is that when any action is performed a number of times under certain conditions, it becomes under those conditions more and more easily performed” (_Journal of Comparative Neurology and Psychology_, 1908, Vol. XVIII, pp. 503-504).

This hypothesis is, like Professor Jennings’, adequate to account for only the one special case, and is adequate to account for that only upon a further limitation of the number of times that the animal may repeat any one of his varied responses to the situation before he has gone through them all once, or reached the one that puts an end to the situation.

The second limitation may be illustrated in the simple hypothetical case of three responses, 1, 2 and 3, of which No. 2 is successful. Suppose the animal always to go through his repertory with _no_ repetitions until he reaches 2 and so closes the series.

Only the following can happen:—

1 2
1 3 2
2
2
3 1 2
3 2

and, in the long run, 2 will happen twice as often as 1 or 3 happens.

Suppose the animal to repeat each response of his repertory six times before changing to another, the remaining conditions being as above. Then only the following can happen:—

1 1 1 1 1 1 2
1 1 1 1 1 1 3 3 3 3 3 3 2
2
2
3 3 3 3 3 3 1 1 1 1 1 1 2
3 3 3 3 3 3 2,

and in the long run 2 will happen one third as often as 1 or 3 and, though always successful, must, by Smith’s theory, appear later and later, so that if the animal meets the situation often enough, he will eventually fail utterly in it!

Animals do, as a matter of fact, commonly repeat responses many times before changing them,[44] so that if only the law of exercise operated, learning would not be adaptive. It is the _effect_ of 2 that gives it the advantage over 1 and 3. Of two responses to the same annoying situation, one continuing and the other relieving it, an animal could never learn to adopt the latter as a result of the law of exercise alone, if the former was, originally, twice as likely to occur. 1 1 2 would occur as often as 2 and exercise would be equal for both. The convincing cases are, of course, those where learning equals the strengthening to supremacy of an originally very weak connection and the weakening of originally strong bonds. An animal’s original nature may lead it to behave as shown below:—

1 1 1 3 1 1 4 1 1 2
1 1 1 1 3 1 1 1 3 1 1 4 2
4 1 1 3 3 1 1 4 4 1 1 1 1 1 2, etc.,

and yet the animal’s eventual behavior may be to react to the situation always by 2. The law of effect is primary, irreducible to the law of exercise.

THE EVOLUTION OF BEHAVIOR

The acceptance of the laws of exercise and effect as adequate accounts of learning would make notable differences in the treatment of all problems that concern learning. I shall take, to illustrate this, the problem of the development of intellect and character in the animal series, the phylogenesis of intellectual and moral behavior.

The difficulties in the way of understanding the evolution of intellectual and moral behavior have been that neither what had been evolved nor that from which it had been evolved was understood.

The behavior of the higher animals, especially man, was thought to be a product of impulses and ideas which got into the mind in various ways and had power to arouse certain acts and other ideas more or less mysteriously, in the manner described by the laws of ideo-motor action, attention, association by contiguity, association by similarity, suggestion, imitation, dynamo-genesis and the like, with possibly a surplus of acts and ideas due to ‘free will.’ The mind was treated as a crucible in which a multifarious solution of ideas, impulses and automatisms boiled away, giving off, as a consequence of a subtle chemistry, an abundance of thoughts and movements. Human behavior was rarely viewed from without as a series of responses bound in various ways to a series of situations. The student of animal behavior passed as quickly as might be from such mere externals to the inner life of the creature, making it his chief interest to decide whether it had percepts, memories, concepts, abstractions, ideas of right and wrong, choices, a self, a conscience, a sense of beauty. The facts in intellect and character that are due to learning, that are not the inherited property of the species and that consequently are beyond the scope of evolution in the race, were not separated off from the facts of original nature. The comparative psychologist misspent his energy on such problems as the phylogenesis of the idea of self, moral judgments, or the sentiment of filial affection.

At the other extreme, the behavior of the protozoa was either contemplated in the light of futile analogies,—for instance, between discriminative reactions and conscious choice, and between inherited instincts and memory,—or studied crudely in its results without observation of what the animals really did. The protozoa were regarded either as potential ‘conscious selves’ or as drifting lumps turned hither and thither by the direct effects of light, heat, gravity and chemical forces upon their tissues.

The evolution of the intellectual and moral nature which a higher animal really possesses from the sort of a nature which the real activities of the protozoa manifest, is far less difficult to explain.

In so far as the higher animal is a collection of original tendencies to respond to physical events without and within the body, subject to modification by the laws of exercise and effect and by these alone, and in so far as the protozoan is already possessed of a well-defined repertory of responses connected with physical events without and within the body in substantially the manner of the higher animal’s original tendencies, the problems of the evolution of behavior are definite and in the way of solution.

The previous sections gave reason for the belief that the higher animals, including man, manifest no behavior beyond expectation from the laws of instinct, exercise and effect. The human mind was seen to do no more than connect in accord with original bonds, use and disuse, and the satisfaction and discomfort resulting to the neurones. The work of Jennings has shown that the protozoa already possess full-fledged instincts, homologous with the instincts of man. They too may have specialized receptors, an action-system with a well-defined repertory and a connecting system or means of influencing the bonds between the stimuli received and the motor reactions made. The difficulties of tracing the possible development of a super-man from an infra-animal thus disappear.

There is, of course, an abundance of _bona fide_ difficulty in discovering the unlearned behavior of each group of animals and in tracing, throughout the animal series, changes in the physical events to which animals are sensitive so that to each a different response may be attached, changes in the movements of which animals are capable, and changes in the bonds by which particular movements follow particular physical events. To find when and how animals whose natures remained nearly or quite unchanged by the satisfying and annoying effects of their behavior, gave birth to animals that could learn, is perhaps a still harder task. But these tasks concern problems that are intelligible matters of fact. They do not require a student to get out of matter something defined as beyond matter, or to get volition out of tropisms, or to get ideas of space and time out of swimming and sleeping.

The evolution of the sensitivities and of the action-systems of animals has already been subjected to matter-of-fact study by naturalists. The evolution of the connection-system will soon be. Each reflex, instinct or capacity, each bond between a given situation presented to a given physiological state and a given response, has its ancestral tree. Scratching at an irritated spot on the skin is older than arms. Following an object that is moving slowly does not have to be explained separately, as a ‘chance’ variation in dogs, sheep and babies. The mechanical trades of man are related to the miscellaneous manipulations of the apes. Little as we know of the connection-systems possessed by animals, we know enough to be sure that a bond between situation and response has ancestors and children as truly as does any bodily organ. Professor Whitman a decade ago showed the possibility of phylogenetic investigation of instinctive connections in a study which should be a stimulus and model for many others. In place of any further general account of the study of the phylogeny of the connection-system, I shall quote from his account of the concrete phylogeny of the instinct of incubation.

“_b. The Incubation Instinct_

1. _Meaning to be Sought in Phyletic Roots._—It seems quite
natural to think of incubation merely as a means of providing
the heat needed for the development of the egg, and to assume
that the need was felt before the means was found to meet it.
Birds and eggs are thus presupposed, and as the birds could
not have foreseen the need, they could not have hit upon the
means except by accident. Then, what an infinite amount of
chancing must have followed before the first ‘cuddling’ became
a habit, and the habit a perfect instinct! We are driven to
such preposterous extremities as the result of taking a purely
casual feature to start with. Incubation supplies the needed
heat, but that is an incidental utility that has nothing to do
with the nature and origin of the instinct. It enables us to
see how natural selection has added some minor adjustments, but
explains nothing more. For the real meaning of the instinct we
must look to its phyletic roots.

If we go back to animals standing near the remote ancestors of
birds, to the amphibia and fishes, we find the same instinct
stripped of its later disguises. Here one or both parents
simply remain over or near the eggs and keep a watchful guard
against enemies. Sometimes the movements of the parent serve to
keep the eggs supplied with fresh water, but aëration is not
the purpose for which the instinct exists.

2. _Means Rest and Incidental Protection to Offspring._—The
instinct is a part of the reproductive cycle of activities,
and always holds the same relation in all forms that exhibit
it, whether high or low. It follows the production of eggs,
or young, and means primarily, as I believe, rest, with
incidental protection to offspring. That meaning is always
manifest, no less in worms, molluscs, crustacea, spiders and
insects, than in fishes, amphibia, reptiles and birds. The
instinct makes no distinction between eggs and young, and that
is true all along the line up to birds, which extend the same
blind instinct to one as to the other.

3. _Essential Elements of the Instinct._—Every essential
element in the instinct of incubation was present long
before the birds and eggs arrived. These elements are:
(1) the disposition to remain with or over the eggs; (2)
the disposition to resist and drive away enemies; and (3)
periodicity. The birds brought all these elements along in
their congenital equipment, and added a few minor adaptations,
such as cutting the period of incubation to the need of normal
development, and thus avoiding indefinite waste of time in case
of sterile or abortive eggs.

(1) _Disposition to Remain over the Eggs._—The disposition to
remain over the eggs is certainly very old, and is probably
bound up with the physiological necessity for rest after a
series of activities tending to exhaust the whole system. If
this suggestion seems far-fetched, when thinking of birds, it
will seem less so as we go back to simpler conditions, as we
find them among some of the lower invertebrate forms, which are
relatively very inactive and predisposed to remain quiet until
impelled by hunger to move. Here we find animals remaining
over their eggs, and thus shielding them from harm, from sheer
inability or indisposition to move. That is the case with
certain molluscs (_Crepidula_), the habits and development of
which have been recently studied by Professor Conklin. Here
full protection to offspring is afforded without any exertion
on the part of the parent, in a strictly passive way that
excludes even any instinctive care. In _Clepsine_ there is a
manifest unwillingness to leave the eggs, showing that the
disposition to remain over them is instinctive. If we start
with forms of similar sedentary mode of life, it is easy to see
that remaining over the eggs would be the most likely thing
to happen, even if no instinctive regard for them existed.
The protection afforded would, however, be quite sufficient
to insure the development of the instinct, natural selection
favoring those individuals which kept their position unchanged
long enough for the eggs to hatch.”[45]

Professor Whitman proceeds to study the ‘Disposition to Resist
Enemies’ and the ‘Periodicity’ in the same genetic way.

The most important of all original abilities is the ability to learn. It, like other capacities, has evolved. The animal series shows a development from animals whose connection-system suffers little or no permanent modification by experience to animals whose connections are in large measure created by use and disuse, satisfaction and discomfort.

Some of this development can be explained without recourse to differences in mere power to learn, by the fact that the latter animals are given greater stimuli to or rewards for learning. But part of it is due to differences in sheer ability to learn, that is, in the power of equally satisfying conditions to strengthen or of equally annoying conditions to weaken bonds in the animals’ connection-systems. This may be seen from the following simple and partial case:—

Call 1 and 2 two animals.

Call C₁ and C₂ the internal conditions of the two animals except for their connection-systems, each being the average condition of the animal in question.

Call S₁ and S₂ two external states of affairs, each being near the indifference point for the animal in question,—that is, being one which the animal does little to either avoid or secure.

Call G₁ and G₂ two responses which result in O₁ and O₂ the _optima_ or most satisfying state of affairs for 1 and 2.

Call I₁ and I₂ two responses which result in the continuation of S₁ and S₂.

The only responses possible for 1 are G₁ and I₁.

The only responses possible for 2 are G₂ and I₂.

Animal 1 upon the recurrence of S₁ and C₁ is little or no more likely to respond by G₁ than he was before.

Animal 2 upon the recurrence of S₂ and C₂ is far more likely to respond by G₂ than he was before.

The fact thus outlined might conceivably be due to an intrinsic inequality between O₁ and O₂, the power of equally satisfying _optima_ to influence, their antecedents being identical. This is not the case in the evolution of learning, however. For even if, instead of O₂, we had only a moderately satisfying state of affairs, such as the company of other chicks to (2) a 15-day-old chick, while O₁ was the optimum of darkness, dampness, coolness, etc., for (1) an earthworm, 2 would learn far, far more rapidly than 1.

The fact is due, of course, to the unequal power of equally satisfying conditions to influence their antecedents. The same argument holds good for the influence of discomfort.

The ability to learn,—that is, the possession of a connection-system subject to the laws of exercise and effect,—has been found in animals as ‘low’ as the starfish and perhaps in the protozoa. It is hard to tell whether the changed responses observed in Stentor by Jennings and in Paramecium by Stevenson Smith are easily forgotten learnings or long retained excitabilities. Sooner or later clear learning appears, and then, from crabs to fish and turtle, from these to various birds and mammals, from these to monkeys, and from these to man, a fairly certain increase in sheer ability to learn, in the potency of a supposedly constant degree of satisfyingness or annoyingness to influence the connection preceding it, can be assumed. We cannot, of course, define just what we mean by equal satisfyingness to a mouse and a man, but the argument is substantially the same as that whereby we assume that the gifted boy has more sheer ability to learn than the idiot, so that if the two made the same response to the same situation and were equally satisfied thereby, the former would form the habit more firmly.

We may, therefore, expect that when knowledge of the structure and behavior of the neurones comprising the connection-systems of animals (or of the neurones’ predecessors in this function) progresses far enough to inform us of just what happens when a connection is made stronger or weaker and of just what effects satisfying and annoying states of affairs exert upon the connection-system (and in particular upon the connections most recently in activity) the ability to learn will show as true an evolution as the ability to sneeze, oppose the thumb, or clasp an object touched by the hand.

If my analysis is true, the evolution of behavior is a rather simple matter. Formally the crab, fish, turtle, dog, cat, monkey and baby have very similar intellects and characters. All are systems of connections subject to change by the law of exercise and effect. The differences are: first, in the concrete particular connections, in _what_ stimulates the animal to response, _what_ responses it makes, _which_ stimulus connects with _which_ response, and second, in the degree of ability to learn—in the amount of influence of a given degree of satisfyingness or annoyingness upon the connection that produced it.

The peculiarly human features of intellect and character, responses to elements and symbols, are the results of: first, a receiving system that is easily stimulated by the external world bit by bit (as by focalized vision and touch with the moving hand) as well as in totals composed of various aggregates of these bits; second, of an action-system of great versatility (as in facial expression, articulation, and the hands’ movements); and third, of a connection-system that includes the connections roughly denoted by babbling, manipulation, curiosity, and satisfaction at activity, bodily or mental, for its own sake; that is capable of working in great detail, singling out elements of situations and parts of responses; and that allows satisfying and annoying states of affairs to exert great influence on their antecedent connections. Because he learns fast and learns much, in the animal way, man seems to learn by intuitions of his own.