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the nervous system, and of this effect we know no more than that it exists. Jennings says that the disturbance set up in the organism by the stimulus, by hunger or confinement, as the case may be, not finding an outlet by one path of discharge, seeks others in succession until one is found which relieves the disturbed condition. This, we have seen, he and others have found to be the case in very low forms of animal life. But the crucial part of the phenomena we are now considering is described in the following sentence: "After repetition of this course of events, the change which leads to relief is reached more directly, as a result of the law of the readier resolution of physiological states after repetition" (208). And that is all we know of the matter. But we may well note the probability that a habit, in the sense of a fixed way of action not innate in the individual, may originate in two ways: first, by the loss of conscious control in the case of a set of actions originally voluntary and guided by ideas; and second, by the gradual increase of speed and accuracy in the performance of a series of actions, never at any time guided by anything but external stimuli. In our own experience, the first kind of habit formation has been of so much interest that it has diverted attention from the second. Yet the latter is shown constantly in the growth of skill that comes through the mere repetition of a series of movements, apart from the "knowing how," which means conscious control.

§ 86. The Psychic Aspect of dropping off Useless Move

ments

The conscious aspect of learning by dropping off useless movements must consist largely in the mere shortening of a period of unpleasantness and unrest. The useless movements are unpleasant, the successful one brings pleasure;

when the latter comes to be performed at once, the consciousness accompanying must be wholly pleasant. Further, the puzzle-box experiments differ from the labyrinth experiments in that the successful movement is not merely turning in one direction rather than another, a habit which might ultimately become perfectly independent of external stimuli; but a reaction upon a particular object. It is evident that in the course of learning, this object, at the outset unnoticed, must come to stand in the centre of the animal's consciousness, the focus of its attention, as soon as it is perceived at all. Such a change would constitute another feature of the consciousness accompanying this form of learning, in addition to the diminishing unpleasantness which goes along with the dropping off of unnecessary movements. A special aspect of experiments on imitation is connected with this process of learning to focus attention on the proper object. Can an animal have his attention "called" to the object by watching some one else operating on it, or must the object gain its power to determine reaction solely by the animal's own experience of the consequences connected with it? Hobhouse's experiments on dogs, cats, and other animal subjects led him to the conclusion that watching his performance did materially assist the animal in this respect. His method was to perform the action of pulling a lever or string repeatedly while the animal was watching; and that this process facilitated learning he thinks evident from the fact that after it had been several times repeated, the behavior of the animal changed in a marked degree; instead of being random, it was definitely directed at the proper object. The suddenness of the transition from random to definite behavior indicates, in Hobhouse's opinion, the effect of being shown. Thus, for example, his dog Jack "after being once shown, . . . learnt to pull

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a stopper out of a jar with his teeth. The stopper fitted into a large round glass jar, and could be lifted with the teeth by a projecting peg. I lifted it out for him once, and left him to deal with the jar, which he did by knocking it over and rolling it all about the room until the meat was jerked out. At the second trial he pulled at the stopper himself with his teeth; and he repeated this many times" (177). A cat with which the writer is acquainted stands on his hind legs and touches a door handle with his paw when he wishes to be let out. He has never succeeded in letting himself out by any such method. It is possible that the habit may have been acquired from the fact that the door is sometimes opened for him after he has done so; but this is by no means always the case. He is often left to mew for some time after he has pawed the handle. There is, then, the possibility that observing human beings open doors may have caused the handle to occupy the focus of his attention; but one's attitude toward this hypothesis should be extremely cautious.

CHAPTER XI

THE MODIFICATION OF CONSCIOUS PROCESSES BY INDIVIDUAL EXPERIENCE (continued)

§ 87. The Inhibition of Instinct

IN still another form of experiment that has been devised to study the ways in which animals learn by experience, the object has been to secure the complete inhibition of an instinctive action. Obviously two factors will come into play here, the strength of the instinct and the force of the modifying experience. The latter factor we might suppose to be strongest when the performance of an instinctive action. could be made attended with pain, and less strong when the performance of some action opposed to instinct has been found to be accompanied by pleasure.

The first case we find apparently illustrated by Morgan's chick in his dealings with a bee; he needed but one experience with that insect to inhibit entirely, the next day, his instinct to peck at it (281, p. 53). On the other hand, Bethe denied consciousness to the crab because, although every time it went into the darkest corner of the aquarium it was seized by a cephalopod lurking there, it did not in six experiences learn to inhibit its negative phototropism; nor did the crabs learn not to snap at meat, though several times when they did so they were seized by the experimenter (28). The case of the crabs is not, however, fairly comparable with that of the chick, for the latter was not really obliged to inhibit his pecking instinct altogether, but only to direct

it away from a certain object, while the crabs had no outlet at all for their photic and nutritive instincts. Very likely a longer course of training than that employed by Bethe might have succeeded in suppressing the instincts. The chick's case really belongs to a form of learning which we shall consider later on; that where the inhibition depends on the discrimination of different stimuli. The purest instance of the kind of modification of behavior by experience at present concerning us is furnished by Möbius's experiments with the pike (276), afterward repeated by Triplett with perch (407). The pike was kept in one half of an aquarium, separated by a glass screen from the other half, in which minnows were swimming about. The pike naturally dashed at them, and received a bump on its nose whenever it did so. After a considerable period of this sort of experience, the glass screen was removed, and the minnows were allowed to swim freely around the pike, when it was found that the latter's instinct to seize them had been wholly inhibited by the disagreeable consequences of such action. Triplett's description of the occasional struggles of the instinct to assert itself is extremely interesting. An analogous case is offered by Goldsmith's account of the shell-inhabiting fish, Gobius, which, when a glass partition was placed between it and its shell domicile, dashed against the glass for a time, but after three and a half hours went around it, and the next day did so after only a quarter of an hour's unsuccessful attempting to get through the partition (146).

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The second kind of training in the inhibition of an instinct, where the performance of an action opposed to instinct is made to produce pleasure, is illustrated by Spaulding's work on "Association in Hermit Crabs." He found that these animals, which are positively phototropic, could be trained

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