shaping (of behavior) = (lab slang, bt) approximation conditioning.
Skinner-box = a space enclosed by a floor and walls of one or another material through which the animal studied cannot escape. It is provided with one or more objects (manipulanda), the movement of which will automatically deliver a reinforcing stimulus. The manipulandum may be a key (to be pecked by a pigeon), a bar (to be pressed by a rat), or a string (to be pulled by a rat), or a panel (to be pushed by a dog or monkey). Used in studies of operant conditioning.
spontaneous recovery = (emp, bt) the term applied to the observation that a response which has been extinguished, and then remains neither elicited nor emitted over a period of absence from the experimental situation, will show when next it appears a strength greater than that observed at the termination of the extinction procedure. A concept often used theoretically to account for regression. A similar phenomenon appears after habituation.
statement = (emp, bt) a stretch of verbal behavior bounded by a change of speaker; hence one that is the discriminative stimulus for some behavior of the second speaker. Statements are "sentences that arc regularly directed to eliciting attention to continuous discourse" (6). Verbal behavior has the property of presenting stimuli both to the behaver himself and to those with respect to whom he is acting.
stereotyping = (emp, bt) a term applied when members of a set of successive instances of a response do not vary in their quantitative topographic characteristics. A response that has been performed with reinforcement many times will be stereotyped. A response that has been carefully differentially reinforced will also show stereotyping, but more quickly. Cf. ritualization.
stimulus = Five usages must be distinguished among the writings of various students of behavior. Fortunately for the intellectual comfort of the reader (but for nothing else), in most cases the ambiguity of this term does not reveal itself, since most students of behavior have not shown any great interest in treating the problem of stimulation in great experimental detail. =1. (emp) a physical event impinging on the receptors of an animal. =2. (emp) a physical event impinging on the receptors of an animal and capable of exciting those receptors. 3. (emp) a specified part, or change in a part, of the environment correlated in an orderly manner with the occurrence of a specified response. See sign stimulus. =4. (th) an event within the animal hypothesized to account for certain complex behavior. See movement-produced stimulus, private stimulus, and drive stimulus. 5. (lab slang) loosely used as synonymous with stimulus object (an object which produces stimuli) and with stimulus event (an event which produces stimuli). Stimulus is a difficult term indeed. In many psychophysical and psychophysiological laboratories, the first usage is often heard (although it is perhaps always incorrect). The second appears as an empirical term in physiological studies of sensory discrimination and as a theoretical term, as in Hullian theory. The third is that explicitly stated by Skinner (22) and corresponds closely to the ethologist's releaser or sign stimulus. The distinction between this usage and the preceding one is related to the distinction that Skinner draws between stimuli that "elicit" and stimuli that "set the occasion for" response, and that ethologists draw between reflex stimulation and the "releasing" action of a sign stimulus or releaser. It is implicitly employed empirically by other American behaviorists. The stimulus for a response, by this usage, is not necessarily descriptively simple, or easily quantifiable, and can only be determined by experimental manipulation of the environment designed to isolate those parts of it on which a particular response is contingent. A response may or may not vary in magnitude as a function of the magnitude of the stimulus (where it can be measured or controlled). Sometimes, the stimulus proves to be complex but invariant, as "a (preferably red) patch at the tip of the lower mandible" for the food begging response of the gull chick (31), or "a (preferably black) angle" for certain cases of discriminated pecking in the pigeon. At other times, the stimulus turns out to be both complex and variable, as those stimuli controlling maze-running in the rat. For an interesting discussion of the concept of stimulus, see Skinner (22). See also stimulus/discriminative and stimulus/sign. In the following series of terms, definition (3.) applies to all the empirical ones, and definition (4.) to the theoretical ones. It should also be noted that the terms are not mutually exclusive in their application to parts of the environment; thus, a reinforcing stimulus may also be a discriminative stimulus. E.g., the click of the food magazine is a reinforcing stimulus for bar-pressing, and a discriminative stimulus for diving to the food-tray, for eating, and, indeed, for the next bar-press in the series. Note, too, that since a given environmental event is a stimulus of a given class at one time for an animal, it is not necessarily a stimulus of any class whatever on other occasions.
stimulus/aversive = (emp, bt) a stimulus which, if it is applied following the occurrence of a response, decreases the strength of that response on later occurrences. Most aversive stimuli are also negatively reinforcing stimuli. It is a live experimental problem to determine whether these are identical classes and hence whether only one term need be employed conceptually. Incidentally, both classes of stimuli also usually elicit the behavioral "symptoms" of fear as well as of avoidance. The decrease in response-strength that is produced by administering aversive stimuli has been experimentally demonstrated to be transitory; the strength of conditioning seems not to be affected.
stimulus/conditioned (CS) = (emp, bt) in classical conditioning, a stimulus which originally does not evoke any response similar to the unconditioned response, but which during conditioning acquires the property of eliciting this response or a similar one. The originally neutral stimulus. Properly, this should perhaps be "conditional" stimulus, but usage dictates this form.
stimulus/consummatory =1. (emp) the stimulus for a consummatory act. =2. (emp, eth) a member of a set of stimuli the occurrence of which most often terminates a given sequence of behaviors, but which does not elicit an observable consummatory act (18).
stimulus/discriminative (SD) = (emp; bt) used with reference to operant behavior. A stimulus which sets the occasion on which a response will be reinforced. If a response is reinforced only when a discriminative stimulus is present, the animal will eventually make the response at a higher rate or in greater magnitude in the presence of that stimulus than in its absence. The usage "to set the occasion for" parallels the ethologist's "to release" and is basal on the same empirical differences from the "elicitation" by a stimulus of the reflex response of a physiologist's reflex. Discriminative stimuli have most of the properties of sign stimuli. In neither of these cases is the stimulus physically quantifiable in any simple manner. It is, of course, possible for an experimenter to produce an easily quantifiable discriminative stimulus by differential reinforcement, but this is rarely done outside of experiments on sensory mechanisms. Since quantification is usually not readily effected, simple R = f(S) laws are often not statable, and consequently nonstimulus variables (e.g., deprivations or other drive operations) tend to be emphasized as controllers of behavior. This should not be taken to mean that discriminative stimuli or sign stimuli are quite unmanipulatable or that quantitative dimensions cannot be defined at all. ''A (preferably red) patch at the tip of the lower mandible" defines the "normal" stimulus for food begging in the gull chick. Black or gray patches at slightly different locations also control the response, its strength being dependent on the degree of similarity to the specification of the normal sign stimulus. Here lies a problem for psychological scaling. (Negative discriminative stimuli are customarily termed SA.)
stimulus/drive (S4) = (th, bt) a stimulus, usually internal, which is hypothesized to occur in and to be uniquely determined by a given drive state. This concept allows drives to have the empirical properties of stimuli. Theories often identify them with specific events within the organism, and so it is possible that they may in the future be empirically defined.
stimulus/eliciting = (emp, bt) the stimulus of a reflex, or the conditioned stimulus of a classical conditioned response.
stimulus generalization = (emp, bt) the behavioral fact that a response conditioned to one stimulus (or set of stimuli) will be elicited by or will occur in the presence of another stimulus (or set of stimuli) which is similar to the conditioned stimulus or discriminative stimulus although there has been no specific training to it. Changes in strength of response to one will covary with changes in strength of response to the other. Observed both in conditioning and in extinction.
stimulus/movement-produced (mps) = (th, bt) hypothetical proprioceptive stimulus set up by a particular response of the animal, postulated in association theory. Most responses may be postulated to produce such stimuli on the basis of sensory physiology so that statements about mps's often reduce to statements about responses serving as stimuli for further behavior. Cf. stimulus/drive. Probable physiological correlates of these include nerve impulses in the proprioceptive fibers of the nervous system, so that some might think this an empirical concept. However, the operations used in experimentally manipulating them are restricted to increasing the physical work involved in a response and introducing responses of varying topography. As with drive stimuli, empirical definition may eventually become possible.
stimulus/private = (emp, th, bt) a part, or a change in a part, of the animal occurring within the animal's body surface, and hence one that is not observable (cannot be responded to) by others except through special instrumentation. E.g., increased pressure within an infected appendix or around an abscessed tooth root. This concept is employed in the theoretical derivation of the verbal behavior termed "introspective." It is the lack of control over the conditions of social reinforcement that renders the observer's responses to private stimuli notoriously unreliable and, hence, that limits the usefulness of the introspective method to special cases.
stimulus/proximal = (emp) a stimulus (2.) more completely specified in terms of physical events occurring at the receptor organ. One may specify a stimulus (2.) as a circular patch of light, so many millimeters in diameter, of such and such a wave length, eight inches in front of the organism's nose. The proximal stimulus here is the retinal image (physically specified) produced in the subject's eye by this stimulus.
stimulus/reinforcing = 1. (emp, bt) in operant conditioning, if it can be shown that the occurrence or termination under specified conditions of an environmental event that is contingent upon some response of the animal alters some measure of that response as determined on later occasions when instances of it appear, and if these changes conform with those defining the empirical concepts of conditioning, then that event is a reinforcing stimulus. Reinforcing stimuli can all be shown to elicit stable specific responses in those situations in which they reinforce a conditioned response. Thus, those stimuli for consummatory responses that have been used in conditioning have proven almost without exception to be positive reinforcing stimuli, and those that elicit escape behavior and fear are usually negative reinforcing stimuli. Some stimuli are reinforcing only when the animal to which they are presented has been previously treated according to certain drive operations: thus, food is not a reinforcing stimulus for the behavior of a satiated animal. Such qualification of the status of a particular part of the environment as a reinforcing stimulus should always be inferred when the term is used. Reinforcing stimuli are identified empirically. General theories of reinforcement attempt to account for their action in terms of properties common to them all. Thus, Hull's drive-reduction theory stresses the view that such reinforcement stimuli act to reduce drives (either primary or secondary), and Guthrian contiguity theory asserts that they act by altering considerably the stimulation impinging on the animal. Some take the view that it is the response to reinforcing stimuli that is effective. It should be noted that many reinforcing stimuli can be observed to be positive reinforcers for some behaviors and negative reinforcers for others. =2. (emp, bt) in classical conditioning, the unconditioned stimulus.= 3. (emp, bt) loosely, but almost universally, a positive reinforcing stimulus. stimulus/negative reinforcing = (emp, bt) a reinforcing stimulus that, if it is terminated following a response, increases the strength of instances of response occurring later in time. If such stimuli are administered following the occurrence of a response, its rate or magnitude usually diminishes. See punishment and stimulus/aversive. Negative reinforcing stimuli usually control escape behavior. Here are a few stimuli that have been found to be negative reinforcing stimuli. The list is short, suggesting the relatively small number of experiments that have been done on this topic: for rats--electrical shocks to the paws, bright lights; for dogs--electrical shocks to the paws, sudden loud noises, hammer blows to the body; and for human adults--electrical shocks, "that's wrong."
stimulus/positive reinforcing = (emp, bt) a reinforcing stimulus that, if applied following a response, increases the strength of instances of that response occurring later in time. Here are a few stimuli that have been found experimentally to be positive reinforcing stimuli for most responses under appropriate conditions: for rats--laboratory chow, water, bread and milk, removal from the experimental situation, saccharin solutions, warmth, dark spaces, and (to the male) females in heat; for fish-meal worms, daphnia, roe; for dogs---meat, meat powder, water, head-pattings by humans; for human infants---lights, gongs; for chimpanzees---peanuts, bananas, and (after appropriate training) poker chips; for human adults---lights, "points," "knowledge of results," smiles, agreement, peanuts, silver, and gold.
stimulus/primary reinforcing =1. (emp, bt) any stimulus that is effective as a reinforcing stimulus for all the known members of a strain or of a species at the beginning of an experiment. Hence, any reinforcing stimulus which has not been shown experimentally to be a secondary reinforcing stimulus. =2. (th, bt) any reinforcing stimulus that reduces a primary drive. If all rats of a colony were raised on laboratory chow and had had nothing else to eat, an experimenter would find that laboratory chow is a primary reinforcer when they are hungry; their behavior could not be reinforced by cheese, nor would they eat it until they had been trained to eat it. If all rats were raised on laboratory chow and cheese, then both would prove to be primary reinforcers when they were used in an experiment.
stimulus/secondary (or conditioned) reinforcing = (emp, bt) after a stimulus has been presented to an animal in spatial and temporal contiguity with a reinforcing stimulus one or more times, if, and only if, it then acts as a reinforcing stimulus itself, it is termed a secondary reinforcing stimulus. Presentation of a secondary reinforcing stimulus is termed secondary reinforcement. The distinction between primary and secondary reinforcing stimuli is based upon the experimental history of the animal and nothing else. The connotations of the modifiers primary and secondary are unfortunate since they imply for many a distinction based on one theory of reinforcement, the drive-reduction theory. For this reason, the term conditioned reinforcing stimulus is to be preferred to the more commonly (and misleadingly) used secondary reinforcing stimulus, since the experimental operations that render a previously neutral stimulus a reinforcing stimulus are the same as those which produce classical conditioned responses.
stimulus-response (S-R or SR) correlation = (emp, bt) an observed relationship between a stimulus and a response, such that a particular response can be shown to be dependent for its occurrence upon the just previous or concomitant occurrence of a specific stimulus or class of stimuli and to vary with variations in the conditions of presentation. Cf. reflex.
stimulus/sign = (emp, eth) a specified part, or change in a part, of the environment correlated in an orderly manner with the occurrence of a species-specific response that is not a reflex response. This term corresponds closely with stimulus (3.) and almost exactly with the term discriminative stimulus. Stimulus (3.) is the definition used empirically by behaviorists. The difference lies in the class of response controlled. A sign stimulus can be identified only on the basis of experimental work. It usually turns out to be specifiable in rather complex but sometimes exact terms, and it is often not conveniently describable in the language of physics and physiology. This leads to the use of literary terms such as "configuration" and then on to the use of Gestalt. Sign stimuli "release" behavior, just as discriminative stimuli "set the occasion for" responses. See also stimulus/super-normal sign.
stimulus/super-normal sign = (emp, eth) a term applied to certain sign stimuli that have proven amenable to quantification along some scale. The sign stimulus, as it occurs in the field, falls at some point on this scale. To stimui below this value, strength or intensity of response is less. If responses are given at greater strength or intensity to stimuli above this value, the stimuli of these magnitudes are referred to as "super-normal stimuli" (that is, they are more effective than "normal" stimuli). A good example is the oversized dummy egg to which the oyster-catcher responds with more vigorous brooding activity than it does to its own egg. The egg is too large for sitting, but the oyster-catcher climbs upon it nonetheless, topples off it, climbs on again, and so on, all the while ignoring its own much smaller egg that lies nearby (29).
stimulus threshold = (emp) the class of those values of quantified stimuli that will elicit some defined constant response at a fixed strength of less than maximal value. E.g., the absolute terminal threshold of vision is defined in terms of the photometric brightness of a stimulus patch of specified characteristics that will elicit "Yes, I see it" from a subject on 50% of all the occasions on which it is presented. Note that not only the stimulus characteristics, but the response characteristics and the magnitude as well, must be specified in defining a threshold.
stimulus-trace = (th, bt) a hypothetical after-effect in the conceptual nervous system that persists for a short time after the termination of a stimulus and that has the properties of a stimulus in controlling response. Not to be confounded with the physiologically observable nerve impulses that may be recorded from afferent fibers after the withdrawal of a stimulus from a receptor. Stimulus-traces are theoretical, and their properties are what they must be to satisfy the needs of theory and not what the physiologist observes. Theorists tend to overlook discrepancies and sanguinely look to the day when the discrepancies will disappear so that stimulus-trace conceptions can take on an empirical status. See Hull (16).
stimulus/unconditioned (US) = (emp, bt) in classical conditioning, a stimulus which evokes or elicits a regular and measurable response (the unconditioned response). Usually the stimulus of a reflex.
superstition =1. (emp, bt, lab slang) unless an experimenter is very careful, during approximation conditioning of a rat, or a pigeon, or a human subject, he may reinforce a response in which he is not interested or reinforce too often one of the responses that is in the approximation sequence of responses. These responses, occurring henceforth at a relatively high rate or in great strength, are referred to as superstitions or as superstitious responses. They tend to recur through the animal's experimental history and, hence, render data on the response in which the experimenter is interested relatively disorderly. =2. (emp, bt, lab slang) if stimuli that are usually reinforcing (e.g., food) are randomly delivered to a pigeon over a long period of time irrespective of his behavior, at the end of the period the subject can be observed to repeat over and over some response. Such a response is termed a superstition (23). It is probably one that occurred just before food was presented, that then increased in rate, was reinforced again, and so on. It has been conditioned despite the fact that reinforcement was not experimentally contingent on it. This procedure bas not been tried on other species.
suppression/conditioned = (emp, bt) the experimental procedure of presenting, on a number of occasions for a short period of time (e.g., 1-5 min.) during the performance of a given pattern of behavior, a neutral stimulus and of presenting, at its termination, a strongly aversive stimulus, neither being contingent on the animal's behavior. Conditioned suppression is said to occur if, and only if, the response-strength is observed to decrease during the presentation of the initially neutral stimulus.