Number 13 SKINNER-B

Number 13 SKINNER-B - Chapter 9 “Superstition” in the...

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Unformatted text preview: Chapter 9 “Superstition” in the pigeon* B. F. Skinner In everyday life a number of otherwise puzzling behaviors con be un- derstood in terms of the accidental shaping of responses that are un- wittingly reinioroed. For example, a child may be reinforced by a few moments of parental attention if he hits his sister, and he may then reinforce his parents with a few moments of silence if he is not spanked. Soon' the pattern is well established, and the mother “iust can't under- stand what's making him act like such a rotten kid. He must take after his father's side of the family." The article by Skinner Illustrates this type of fortuitous shaping of responses under laboratory conditions. To say that a reinforcement is contingent upon a response may mean nothing more than that it follows the response. It may follow because of some mechanical connection or because of the mediation of another organism; but conditioning takes place presumably because of the temporal relation only, expresscd in terms of the order and proximity of response and reinforcement. Whenever we present a state of aii'airs which is known to be reinforcing at a given drive, we must suppose that conditioning takes place, even though we have paid no attention to the behavior of the organism in making the presentation. A simple experiment demonstrates this to be the case. A pigeon is brought to a stable state of hunger by reducing it to 1'5 perv cent of its weight when well fed. It is put into an experimmtal cage for a few minutes each day. A food hopper attached to the cage may be swung into place so that the pigeon can eat from it. A solenoid and a timing relay hold the hopper in place for five sec. at each reinforcement. If a clock is now arranged to present the food hopper at regular intervals with no reference whatsoever to the bird’s behavior, operant conditioning- usuelly takes place. In six out of- eight cases the resulting responses were so clearly defined that two observers could agree perfectly in counting instances. One bird was conditioned to turn counter-clockwise about the cage, making “From Journal of Experimental Psychology 38:168-172, 1948. Copyright 1948 by Ameri- can Psychological. Association. Used with permission of the author and American Psyh chological Association. I) two or three turns between reinforcements. Another repeatedly thrust its head into one of the upper corners of the cage. A third developed a “tossing” mponse, as if placing its head beneath an invisible bar and lifting it re— peatedly. Two birds developed a pendulum motion of the head and body, in which the head was extended forward and swung from right to left with a sharp movement followed by a somewhat slower return. The body generally followed the ntovement and a few steps might be taken 'when it was exten- sive. Another bird was conditioned to make incomplete pecking or brushing movements directed toward but not touching the floor. None of these re- sponses appeared in any noticeable strength during adaptation to the cage or until the food hopper was periodically presented. In the remaining two cases, conditioned responses were not clearly mark . The conditioning process is usually obvious. The bird happens to be executing some response as the hopper appears; as a result it tends to repeat this response. If the interval before the next presentation is not so great that _ extinction takes place, a second “contingency” is probable. This strengthens the mponse still further and-subsequent reinforcement becomes more prob- able. It is true that some responses go unreinforced and some reinforcements appear when the response has not just been made, but the net result is the development of a considerable state of strength. With the exception of the counter-clockwise turn, each response was almost always repeated in the same part of the cage, and it generally in- volved an orientation toward some feature of the cage. The effect of the reinforcement was to condition the bird to respond to some aspect of the environment rather than merely to execute a series of movements. All re- sponses came to be repeated rapidly between reinforcements—typically five or six timhs in 15 sec. The effect appears to depend upon the rate of reinforcement. In general, we should expect that the shorter the intervening interval, the speedier and more marked the conditioning. One reason is that the pigeon’s behavior becomes more diverse as time passes after reinforcement. A hundred photo- graphs, each taken two see. after withdrawal of the hopper, would show fairly uniform behavior. The bird would be in the same part of the cage, near the hopper, and probably oriented toward the wall where the hopper has disappeared or turning to one side or the other. A hundred photographs taken after 10 sec., on the other hand, would find the bird in various parts of the cage responding to many different aspects of the environment. The sooner a second reinforcement appears, therefore, the more likely it is that the second reinforced response will be similar to the first, and also that they will both have one of a few standard forms. In the limiting case of a very brief interval the behavior to be expected would be holding the head toward the opening through which the magazine has disappeared. Another reason for the greater effectiveness of short intervals is that the longer the interval, the greater the number of intervening responses emitted without reinforcement. The resulting extinction cancels the effect of an occasional reinforcement. . _ According to this interpretation the effective interval will depend upon “the rate of conditioning and the rate of extinction, and will therefore var}r with the drive and also prestunably bettaveen species. Fifteen see. is a very efi'ective interval at the drive level indicated about. One minute is much less so. When a response has once been set up, however, the interval can be lengthened. In one case it was extended to two min., and a high rate of. responding was maintained with no sign of weakening. In another case, many'hours of responding were observed with an interval of one min. be- tween reinforcements. ' I ‘ In the latter case, the response showed a noticeable drift in topography. It began as a sharp movement of the head from the middle position to the left. This movement became more energetic, and eventually the whole body of the bird turned in the same direction, and a step or two w0uld be taken. ' After many hours, the stepping response became the predominant feature. The bird made a well defined hopping step from the right to the left foot, _ meanwhile turning its head and body to the left as before. When the stepping response became strong, it was possible to obtain a mechanical record by putting the bird on a large tambour directly con— nected with a small tambour which made a delicate electric contact each I time stepping took place. By watching the bird and listening to the sound of the recorder it was possible to confirm the fact that a. fairly authentic record was being made. It was possible for the bird to hear the recorder at each step, but this was, of course, in no way correlated with feeding. The record obtained when the magazine was once every min. resembles ' in every respect the characteristic curve for the pigeon under periodic rein- forcement of a standard selected response. A well marked temporal discrimi- nation develops. The bird does not respond immediately after“ eating, but when 10 or 15 or even 20 sec. have elapsed it begins to respond rapidly and continues until the reinforcement is received. - In this case it was possible to record the “extinction” of the response when the clock was turned off and the magazine was no longer presented at any time. The bird continued to respond with its characteristic side to side hop. More than 10,000 responses were recorded before “extinction” had reached the point at which few if any responses were made during a 10 or 15 min. interval. When the clock was again started, the periodic presentation of the magazine (still without any connection whatsoever with the bird's behavior) brought out a typical curve for reconditioning after periodic reinforcement. . . The record had been essentially horizontal for 20 min. prior to the be- ginning oi this curve. The first reinforcement had some slight «fleet and the second a greater effect. There is a smooth positive acceleration in rate as the bird returns to the rate of responding which prevailed when it was-reinforced every min. ' ‘ When the response was again extinguished and the periodic presentation of food then resumed, a difl'erent response was picked up. This consisted of a progressive walking response in which the bird moved about the cage. The response of hopping from side to side never reappeared and could not, of course, be obtained deliberately without making the reinforcement con- tingent on the behavior. The experiment might be said to demonstrate a sort of superstition. The bird behaves as if there were a causal relation between its behavior and the presentation of food, although such a relation is lacking. There are many analogies in human behavior. Rituals for changing one’s luck at cards are good examples. A few accidental connections between a ritual and favorable conseguences sulfice to set up and maintain the behavior in spite of many unreinforced instances. The bowler who has released a ball down the alley but continues to behave as if he were controlling it by twisting and turning his arm and shoulder is another case in point. These behaviors have, of course, no real effect upon one’s luck or upon a ball halfway down an alley, 'just as in the present case the food would appear as often if the pigeon did nothing—or, more strictly speaking, did something else. It is perhaps not quite correct to say that conditioned behavior has been set up without any previously determined contingency whatsoever. We have appealed to a uniform sequence of responses in the behavior of the pigeon to obtain an over-all net contingency. When we arrange a clock to present food ever 15 sec., we are in effect basing our reinforcement upon a limited set of responses which frequently occur 15 sec. after reinforcement. When a re— sponse has been strengthened (and this may result from one reinforcement), the setting of the clock implies an even more restricted contingency. Some- thing of the same sort is true of the bowler. It is not quite correct to say that there is no connection between his twisting and turning and the course taken by the ball at the far end of the alley. The connection was established before the ball left the bowler’s hand, but since both the path of the ball and the behavior of the bowler are determined, some relation survives. The subsequent behavior of the bowler may have no effect upon the ball, but the ball has an efi'ect upon the bowler. The contingency, though notperfect, is enough to maintain the behavior in strength. The particular form of the behavior adopted by the bowler is due to induction from responses in which there is actual contact with the ball. It is clearly a movement appropriate to changing the hall’s direction. But this does not invalidate the comparison, since we are not concerned with what response is selected but with why it persists in strength. In rituals for changing luck the inductive of a particu- lar form of behavior is generally absent. The behavior of the pigeon in this experiment is of the latter sort, as the variety of responses obtained from different pigeons indicates. Whether there is any unconditioned behavior in the pigeon appropriate to a given effect upon the environment is under in- vestigation. ' The results throw some light on incidental behavior observed in experi- ments in which a discriminative stimulus is frequently presented. Such a stimulus has reinforcing value and can set up superstitious A pigeon will often develop some response such as turning, twisting, pecking near the - locus of the discriminative stimulus, flapping its wings, etc. In much of the work to date in this field the interval between presentations of the discrimina- tive stimulus has been one min. and many of these superstitious responses are short—lived. Their appearance as the result of accidental correlations with the presentation of the stimulus is unmistakable. ...
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This note was uploaded on 04/03/2008 for the course PSYC 1000 taught by Professor Carter during the Spring '07 term at Montana Tech.

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Number 13 SKINNER-B - Chapter 9 “Superstition” in the...

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