A fixed interval schedule in which the interval is initiated by a response

The fixed interval schedule described requires the animal to initiate every time interval by making a response on a bar other than the one on which it is reinforced. This response, R(A), demarcates the postreinforcement pause (S(R)-R(A) interval) from the fixed interval pause (R(A)-R(B) interval) so that these pauses may be measured separately. Twelve rats and three monkeys, working in two-bar Skinner boxes, were trained and stabilized on this schedule. The resulting performances, presented for individual animals, are analyzed in terms of (1) the relative frequencies with which the animal waits various lengths of time between consecutive responses, (2) the relative frequencies with which various rates of responding appear, (3) the change in response rate throughout the fixed interval, (4) the average length of the postreinforcement pause, (5) the relative frequencies with which the animal waits different lengths of time between the R(A) and the first R(B), and (6) the average inter-response time as a function of the rank order in the fixed interval of the inter-response time. The joint interpretation of the several measures taken leads to the following conclusions: 1. The probability of an R(B) increases throughout the fixed interval. 2. The increase is discontinuous at the first R(B), at which point the probability increases sharply. 3. The frequency distributions of R(A)-R(B) pauses exhibit three discrete types of behavior with no intermediate cases. 4. The (main) mode of R(A)-R(B) interval length usually occurs just below the fixed interval requirement.

Amplitude-induction gradient of a small-scale (covert) operant

An invisibly small thumb-contraction was conditioned under secondary positive reinforcement (money) in four adult human subjects without their observation of the response. Electromyo-graphic detection enabled the experimenter to reinforce the response by advancing on the subject's illuminated scoreboard the count of nickels earned. A light-beam galvanometer recorded on photosensitive paper not only those instances of the response which were of the size pre-selected for reinforcement but also those too small or too large to qualify. From the developed record cumulative response curves were constructed for each of the variously sized subclasses of the operant. Histograms, too, were plotted showing response-frequency by subclass for each 10-min interval of the experimental session. Before conditioning, response frequency was radically skewed toward the large-amplitude end of the distribution. The effect of conditioning was to normalize the distribution, with the middle-sized subclass (the one reinforced) becoming modal. This entailed reduced frequency of responses in subclasses smaller than the one reinforced. In extinction the original skew was strikingly restored in three of the four cases.

Effects of asarone and beta-asarone on conditioned responses, fighting behaviour and convulsions

In the Ayurvedic system of medicine, the roots and rhizomes of an indigenous Indian plant Acorus calamus are used together with the roots of Rauwolfia serpentina for treating many mental ailments. The influence of asarone and beta-asarone (the trans and cis forms of 2,4,5-trimethoxy-1-propenyl benzene), two active principles of Acorus calamus, when given alone and together with either reserpine or chlorpromazine, has been studied on the conditioned avoidance response of trained rats, on the fighting behaviour of paired mice subjected to mild foot shock and on electro-convulsions. Except for electro-convulsions, asarone in small doses potentiates the effects of reserpine and of chlorpromazine; beta-asarone has no such effect. Estimation of the 5-hydroxytryptamine content of rat brain showed that neither acorus oil nor its active principles increase the concentration of 5-hydroxytryptamine; nor do these compounds cause an additional decrease in the 5-hydroxytryptamine content of the brains of animals treated with reserpine. It is concluded that the potentiating effect of these principles is unrelated to 5-hydroxytryptamine concentration. In experiments using electro-convulsions, asarone increased the percentage mortality of animals treated with chlorpromazine but not of those treated with reserpine.

Fixed-interval performances with added stimuli in monkeys

The performance of two monkeys, on fixed-interval schedules, was examined with a visual, an auditory and a combined auditory-visual clock. The clock, a voltmeter and/or a variable frequency tone, produced performances different in many aspects from those recorded earlier with pigeons. Instead of the sustained high rates of responding at the optimal settings of the clock, the monkey's rates of responding were often extremely low even though a limited-hold contingency was utilized.

Reflexive fighting in response to aversive stimulation

Reflexive fighting was elicited between paired rats as a reflex reaction to electric shock prior to any specific conditioning. Such fighting was fairly stereotyped and easily differentiated from the rats' usual behavior. The strength of this reflex was not attributable to any apparent operant reinforcement. Elicitation of fighting was a direct function of the enclosed floor area and a nonmonotonic function of the shock intensity. Failure to scramble the polarity of the electrified grid produced inconsistent fighting. Under optimal conditions fighting was consistently elicited by shock regardless of the rat's sex, strain, previous familiarity with each other, or the number present during shock. Repeated shock presentations did not produce an appreciable decrease in fighting until signs of physical debility appeared. Although shock did not cause a rat to attack inanimate objects, it did produce attack movements toward other small animals. Failure of guinea pigs to defend themselves revealed that the elicitation of fighting from the rat does not require reciprocal attack. Paired hamsters showed fighting reactions similar to those of the rats, whereas guinea pigs failed to fight. Electrode shock and a heated floor elicited fighting between the rats, but intense noise and a cooled floor did not.

Intermittent punishment of Sdelta responding in matching to sample

Incorrect matching responses of two pigeons on matching to sample were either continuously (CRF) or intermittently (FR) followed by a time out (TO). The matching accuracy was examined as a function of both TO duration and TO frequency (ratio size). With intermediate TO durations (10 sec, 1 min), accuracy increased as the frequency of TO increased. With an extremely short (1 sec) and an extremely long (10 min) TO duration, accuracy was poor over the entire range of frequencies.

Operant control of vocal behavior in the cat

EVIDENCE OF OPERANT CONTROL OF VOCAL BEHAVIOR IN THE CAT IS PRESENTED: (1) On mult FR 12 S(Delta) schedule, cats miaowed rapidly during periods of S(D) and much less or not at all during S(Delta). (2) This control was re-established following reversal of stimuli. (3) The frequency distribution of response durations was shifted to both shorter and longer values by the differential reinforcement of shorter or longer response durations respectively. Since both the frequency and duration of vocal responses were shown to be under the control of the schedule of reinforcement, it is concluded that at least some of the vocal behavior of the cat is susceptible to operant control.

The effect of two schedules of primary and conditioned reinforcement

Of 23 pigeons, 11 received continuous reinforcement for key pecking, and 12 received an FR 10 schedule of reinforcement. The birds were then tested without food, but with potential conditioned reinforcers presented either on the same schedule as in training, on the other schedule, or not at all. Each bird in the subgroup trained on CRF and tested with S(r)'s at FR 10 not only gave more responses in testing than did each bird in both subgroups receiving no S(r)'s, but also gave more responses than did each bird in the S(r) subgroup receiving CRF training and S(r)'s at CRF. Cumulative records are presented to show the effects of different schedules of conditioned reinforcers.

A review of positive conditioned reinforcement

This review critically analyzes experimental data relevant to the concept of conditioned reinforcement. The review has five sections. Section I is a discussion of the relationship between primary and conditioned reinforcement in terms of chains of stimuli and responses. Section II is a detailed analysis of the conditions in which the component stimuli in chained schedules of reinforcement will become conditioned reinforcers; this section also analyzes studies of token reinforcement, observing responses, switching responses, implicit chained schedules, and higher-order conditioning. Section III analyzes experiments in which potential conditioned reinforcers are used either to prolong responding or to generate responding during experimental extinction. This section discusses hypotheses that have been offered as alternatives to the concept of conditioned reinforcement and hypotheses concerning the necessary and sufficient conditions for establishing a conditioned reinforcer. Section IV discusses other variables that act when a conditioned reinforcer is being established or that act when an established conditioned reinforcer is used to develop or maintain behavior. Section V is a general discussion of conditioned reinforcement. The evidence indicates that the conditioned reinforcing effectiveness of a stimulus is directly related to the frequency of primary reinforcement occurring in its presence, but is independent of the response rate or response pattern occurring in its presence. Results from chained schedules comprised of several components indicate that a stimulus can be established as a conditioned reinforcer by pairing it with an already established conditioned reinforcer rather than a primary reinforcer; however, this type of higher-order conditioning has not been clearly demonstrated with respondent conditioning procedures. Although discriminative stimuli are usually conditioned reinforcers, the available evidence indicates that establishing a stimulus as a discriminative stimulus is not necessary or sufficient for establishing it as a conditioned reinforcer. Discriminative stimuli in chained schedules with several components are not always conditioned reinforcers; stimuli that are simply paired with reinforcers can become conditioned reinforcers. The hypotheses that have been offered as alternatives to the concept of conditioned reinforcement are too limited to integrate the data that exist. The concepts of conditioned reinforcement and chained schedule, however, can be used to integrate the data obtained with diverse techniques. Recent experiments have revealed several techniques for the development of effective conditioned reinforcers. These techniques provide a powerful tool for advancing understanding of conditioned reinforcement and for extending control over behavior.

Aversive training: long-term effects

Three years ago a tone ending in unavoidable electric shock was periodically presented to pigeons while they pecked a key for food. When pecking was disrupted by tone, shock was disconnected and the training tone and tones of different frequencies were presented. At first all tones caused a reduction in the rate of pecking, but as testing proceeded the gradient narrowed. In our study, testing was resumed after a 2(1/2)-year interruption. Despite the interruption the tones still suppress behavior.

Some effects of combined S-DS

When the individual S(D) components of a multiple schedule were combined, their control over a response summated, thus increasing the response probability to a point over that controlled by either of the S(D)s independently. Summation was concluded to be a phenomenon relevant for operant as well as respondent stimulus control (Pavlov, in Kimble, 1960; Hull, 1943). The results of the present study appear to be a special case of the general S(D) enhancement effect demonstrated by Hanson (1959) and by Pierrel and Sherman (1960).

Fetishism treated by negative conditioning

Negative conditioning or aversion therapy is most frequently thought of in relation to the treatment of alcoholism. The article by Franks (1958) gives an excellent review of the general principles involved. However, Eysenck (1960) includes several papers in his book to illustrate the effectiveness of such treatment in cases of homosexuality, writer's cramp (Liversedge and Sylvester, 1955) and fetishism (Raymond, 1956). A suggestion made in the latter was that the fetishist may well become such because of an unusual capacity for quickly forming conditioned responses, and therefore by the same token might equally easily respond to a de-conditioning technique. For this reason, the following case was treated by behaviour therapy by a psychiatrist and clinical psychologist in collaboration, and is reported in support of Raymond's (1956) advocacy of this technique of treatment in similar cases.