Conditioned suppression of drl responding: Effect of ucs intensity, schedule parameter, and schedule context

In Experiment I, groups of rats were trained to press a lever for food reinforcement on differential reinforcement of low rate (DRL) schedules which differed in parameter value. A stimulus which terminated with either a 0.5-mA or 2.0-mA electric shock was then superimposed upon each DRL baseline. In general, the magnitude of conditioned suppression was an inverse function of DRL schedule parameter and a direct function of shock intensity. Experiment II demonstrated that the rate of responding maintained by the DRL component of a multiple DRL-extinction schedule decreased during a stimulus preceding a 0.5-mA shock, whereas the rate of responding maintained by the DRL component of a multiple DRL-variable interval schedule showed little change or increased slightly during a stimulus preceding a 0.5-mA shock.     

Differential reinforcement of low rates of responding (DRL) to reduce dysfunctional social behaviors of a head injured man

Differential reinforcement of low rates of responding (DRL) is a technique in which a positive reinforcer is delivered at the end of a specific interval if a target behavior has occurred at a criterion rate. Traditionally, it has been used in educational settings to manage classroom behaviors. Recently, therapists have begun to use DRL to reduce the rates of a variety of behaviors in non-educational settings. In this study, DRL was part of a behavioral intervention to reduce dysfunctional verbal and physical behaviors of a head-injured young man. The complete intervention program included DRL, changing criteria, and token reinforcement. Over a period of 15 weeks, the intervention resulted in reductions in behaviors in both categories from high rates to near-zero rates.     

Visual evoked potential augmenting/reducing slopes in cats—2. Correlations with behavior

Relationships were studied in cats between the augmenting/reducing slopes of visual evoked potentials (VEP) and three types of behavioral responses: learning and performance measures in (1) fixed interval (FI), and (2) differential reinforcement of low rate of response (DRL) bar pressing tasks for food reward, and (3) the effect of noise stress or increasing task difficulty on performance of an FI, DRL or 2 bar discrimination task. The most reliable slope measure (N1 at a medium intensity range) was found to correlate most highly with inhibitory behaviors such that reducers were most successful in controlling bar pressing behavior during an inhibitory DRL task or when stress was introduced. At a higher range of flash intensity slopes tended to be more negative, and the P1 - N1 slopes although more variable correlated most consistently with general temperament. Augmenters at a high intensity range were more active and explaratory, and learmed to bar press more quickly and efficiently.     

EFFECTS OF SPACED RESPONDING DRL ON THE STEREOTYPED BEHAVIOR OF PROFOUNDLY RETARDED PERSONS

Stereotypic responding and social behaviors of three profoundly retarded children were measured before and during application of a DRL contingency for stereotypic responding. A variant of the standard DRL procedure, spaced responding DRL, was used, in which reinforcement is delivered following a response if that response has been separated from the previous response by at least a fixed minimum time interval. Three children were treated by using a reversal design. Results showed that: (a) during baseline sessions, the children engaged in high rates of stereotypic responding and very low rates of appropriate social behavior; and (b) during DRL sessions, appropriate behavior increased markedly as stereotypic responding was reduced. The data suggest that spaced responding DRL may be effective in increasing appropriate social behavior as well as in reducing stereotypic responding.     

THE EFFECT OF CHANGES IN CRITERION VALUE ON DIFFERENTIAL REINFORCEMENT OF LOW RATE SCHEDULE PERFORMANCE

The differential reinforcement of low rate (DRL) schedule is commonly used to assess impulsivity, hyperactivity, and the cognitive effects of pharmacological treatments on performance. A DRL schedule requires subjects to wait a certain minimum amount of time between successive responses to receive reinforcement. The DRL criterion value, which specifies the minimum wait time between responses, is often shifted towards increasingly longer values over the course of training. However, the process invoked by shifting DRL values is poorly understood. Experiment 1 compared performance on a DRL 30‐s schedule versus a DRL 15‐s schedule that was later shifted to a DRL 30‐s schedule. Dependent measures assessing interresponse time (IRT) production and reward‐earning efficiency showed significant detrimental effects following a DRL schedule transition in comparison with the performance on a maintained DRL 30‐s schedule. Experiments 2a and 2b assessed the effects of small incremental changes vs. a sudden large shift in the DRL criterion on performance. The incremental changes produced little to no disruption in performance compared to a sudden large shift. The results indicate that the common practice of incrementing the DRL criterion over sessions may be an inefficient means of training stable DRL performance.     

Multiple reinforcement contingencies to reduce aggression,self-injury and dysfunctional verbal behaviors in an adult who is sensory impaired

Differential reinforcement of other behavior (DRO) and differential reinforcement of low rates of responding (DRL) have been effective techniques in reducing maladaptive behaviors in therapeutic settings. Reported studies of these reinforcement-based procedures indicate that they are usually implemented in isolation, targeting only a single behavior or class of behaviors. In this study, multiple DRO and DRL contingencies were utilized concurrently in reducing two distinct classes of behaviors with a 26 year-old blind man with moderate retardation. One class of behaviors included socially inappropriate verbalizations, while the other included aggressive, self-injurious and environmentally destructive behaviors. Distinct contingencies were established according to the functions of the targeted behaviors and their severity and separate schedules of reinforcement were derived from baseline frequencies. Over a period of 20 months, the differential reinforcement interventions resulted in rapid reduction of behaviors in both classes to near-zero rates and frequencies were maintained at this low level while contingency schedules were systematically lengthened. Collateral effects are discussed including performance in functional academics and participation in community integration activities.     

Some properties of spaced responding in pigeons

Pigeons exposed to a schedule which reinforces interresponse times (IRTs) longer than a given value (DRL schedule) eventually reach a stable pattern of responding which is shown to be a function both of the DRL value and of previous experience with other DRL values. On any given DRL schedule, the stable performance of most pigeons which have been previously exposed to a variety of such schedules, shows an IRT distribution with median equal to the DRL value. For DRL values longer than about 30 sec, however, the median IRT falls short of the DRL value; this failure of adjustment to longer values appears to be a species characteristic of pigeons. The function relating reinforcement rate to 1/DRL value is also shown to be approximately linear over the same range, with variable slope (less than 45°) and a downturn in the vicinity of DRL 30.     

Conditioned suppression or facilitation as a function of the behavioral baseline

Rats were exposed to a multiple schedule of reinforcement. During one component, a bar-press was followed by reinforcement only if it occurred between 15 and 20 sec after the previous response. This differential-reinforcement-of-low-rate (DRL) schedule produced a typical slow rate of responding. During the other component, reinforcement followed the first response to be emitted during limited periods of time which occurred at fixed intervals. These fixed-interval schedules with a limited hold produced higher response rates, described as `interval' or `ratio-like' behavior. Responding during the DRL component increased in frequency during a tone which ended with an unavoidable shock of low intensity, but decreased during the tone when the shock intensity was raised. The `interval' and `ratio-like' responding decreased in frequency during the tone at all shock intensities. Initial acceleration of the DRL responding appeared to be due to adventitious punishment of collateral behavior which was observed between the bar-presses. The more severe conditioned suppression during the fixed-interval components might be the result of the lower probability of reinforcement after any single response.     

Punishment of temporally spaced responding

The responses of pigeons were maintained by a DRL schedule of food reinforcement. With this schedule, responses were reinforced only when a fixed period of time elapsed without an intervening response. Punishment of all responses reduced the frequency of these responses as a direct function of the punishment intensity. As a consequence of the increased temporal spacing of responses, more reinforcements resulted during punishment. Under progressively higher intensities of punishment, the reinforcement frequency increased to a maximum value and then decreased at the highest intensities. The increased frequency of reinforcement which resulted during punishment did not counteract the suppressive effect of punishment, nor did it lead to a low response rate after punishment was removed. Punishment did not reduce the inter-response time distribution uniformly, but rather especially reduced the number of short inter-response times. Even at the low punishment intensities, the number of short inter-response times was considerably reduced. After punishment was discontinued, performance recovered almost completely after a compensatory burst. The number as well as the temporal pattern of responses returned to normal.     

Choice between response units: The rate constancy model

In a conjoint schedule, reinforcement is available simultaneously on two or more schedules for the same response. The present experiments provided food for key pecking on both a random-interval and a differential-reinforcement-of-low-rate (DRL) schedule. Experiment 1 involved ordinary DRL schedules; Experiment 2 added an external stimulus to indicate when the required interresponse time had elapsed. In both experiments, the potential reinforcer frequency from each component was varied by means of a second-order fixed-ratio schedule, and the DRL time parameter was changed as well. Response rates were described by a model stating that time allocation to each component matches the relative frequency of reinforcement for that component. When spending time in a given component, the subject is assumed to respond at the rate characteristic of baseline performance. This model appeared preferable to the absolute-rate version of the matching law. The model was shown to be applicable to multiple-response concurrent schedules as well as to conjoint schedules, and it described some of the necessary conditions for response matching, undermatching, and bias. In addition, the pigeons did not optimize reinforcer frequency.     

Operant behavior and the galvanic skin potential under DRL schedule

Motor and galvanic skin potential (GSP) activity were investigated during the conditioning, extinction, and reconditioning of motor responses under a differential reinforcement of low rate (DRL) schedule of reinforcement. Interresponse time (IRT) distributions for motor responses during conditioning and reconditioning gradually stabilized at a peak just beyond the minimal IRT required for reinforcement. Few unreinforced motor responses and "bursts" of motor responses were observed during conditioning and reconditioning. Relative to conditioning and reconditioning, extinction effected larger IRTs and smaller GSP amplitudes. GSP amplitudes were greater for unreinforced than for reinforced motor responses during conditioning and reconditioning. However, GSP amplitudes associated with the unreinforced extinction responses were smaller than either the reinforced or unreinforced responses during conditioning and reconditioning.     

DIFFERENTIALLY REINFORCING LOW RATES OF MISBEHAVIOR WITH NORMAL ELEMENTARY SCHOOL CHILDREN1

Effective nonpunitive procedures for reducing counterproductive classroom behaviors are of potential benefit to both students and teachers. A recent strategy for dealing with this class of problem behaviors involves the reinforcement of acceptably low levels of such behavior. The laboratory version of this procedure, called differential reinforcement of low rates of responding (or DRL), provides for a reinforcer to be delivered contingent upon a response that is separated from the last preceding response by a minimum amount of time. To make this procedure more amenable to classroom use, the present authors have modified it so that a reinforcer is delivered if fewer than a specified number of responses occur within a preset time interval (Deitz and Repp, Journal of Applied Behavior Analysis, 1973, 6 , 457–463). Previous studies using this procedure have found it effective in reducing and maintaining low rates of targeted behaviors. However, these effects have been demonstrated with groups of subjects and/or individuals from dependent populations. The present study investigated use of this modified DRL procedure with individual students in normal elementary classrooms. In the first of three studies, “talk-outs” of an 11-yr-old fifth-grade male were reduced when nonexchangeable gold stars were made contingent on two or fewer responses per session. During baseline sessions, an average of 4.45 talkouts were observed per 45-min session. Average responding subsequently fell to 1.83 when the modified DRL contingency was applied, increased to 7.60 during a reversal phase, and dropped again to an average of 1.20 when the contingency was reapplied. In the second study, out-of-seat behavior of a 12-yr-old sixth-grade female was reduced when gold stars were made contingent on two or fewer responses per 45-min class period. Baseline responding averaged 6.10 responses per session. When the contingency was applied, average responding fell to 0.16. During the reversal period, responding increased to an average of 6.00 and fell again, after the contingency was re-introduced to an average of 0.40. In the third study, a reduction in both talking-out and out-of-seat behaviors of another 11-yr-old fifth-grade male was demonstrated with a multiple-baseline design. Using different lengths of baselines, gold stars were made contingent first on a low rate of out-of-seat behavior, and then on a low rate of talk-outs. Out-of-seat responding fell from a baseline average of 7.50 to a treatment average of 1.14. Talk-outs went from a baseline average of 4.66 to a treatment average of 1.14. In all three studies, the modified DRL procedure proved effective with the children and was manageable by the classroom teacher. For the students, nonexchangeable conditioned reinforcers (stars) were sufficient to maintain lowered rates of inappropriate behavior with the modified DRL schedule; there was no need for an elaborate token economy, a process that in many cases may be only a form of behavioral “overkill”. As in other studies investigating DRL schedules, students were not informed of their accumulation of responses; the differential effects of providing or withholding this feedback need to be investigated. Overall, these studies add single-subject replication with normal children to the literature on modified DRL procedures.     

Effects of dl-amphetamine under concurrent VI DRL reinforcement

Three adult, food-deprived rats were given IP injections of dl-amphetamine sulfate under DRL and concurrent VI DRL reinforcement schedules. The drug results were as follows.(1) The IRT distributions of DRL responses shifted to the left, but some temporal discrimination remained. (2) The IRT distributions of VI responses shifted slightly to the left. (3) The distinguishing characteristics of VI and DRL IRT distributions were preserved. (4) The frequency distribution of number of VI responses between two consecutive DRL responses was relatively unaffected. (5) Over-all response rates on the two components of the concurrent schedules increased more or less proportionately.These findings imply that the primary behavioral effect of dl-amphetamine was a motor excitatory one. The drug's disruption of timing behavior was not due to a derangement of internal timing mechanisms, nor to interference with the topography or pattern of behavior. Rather, it might be a secondary result of the accelerated emission of overt behavior patterns mediating the temporal spacing of DRL bar presses.     

Pigeons' performance under differential reinforcement of low rate schedules depends upon the operant

Pigeons were reinforced with grain for pecking a key or depressing a foot treadle according to differential reinforcement of low rate (DRL) schedules. Birds which depressed a treadle performed efficiently on DRL schedules as high as DRL 35-sec; while birds reinforced for keypecking showed low efficiency under DRL 14-sec. While treadle pressing and keypecking differ along a number of dimensions (including force requirement of the operant and differences in temporal distributions of responses), the present results are consistent with an interpretation based on differences in the degree to which these two responses are elicited by periodic presentations of food.     

Effects of reinforcer magnitude on responding under differential-reinforcement-of-low-rate schedules of rats and pigeons

Experiment I investigated the effects of reinforcer magnitude on differential-reinforcement-of-low-rate (DRL) schedule performance in three phases. In Phase 1, two groups of rats (n = 6 and 5) responded under a DRI. 72-s schedule with reinforcer magnitudes of either 30 or 300 microl of water. After acquisition, the water amounts were reversed for each rat. In Phase 2, the effects of the same reinforcer magnitudes on DRL 18-s schedule performance were examined across conditions. In Phase 3, each rat responded unider a DR1. 18-s schedule in which the water amotnts alternated between 30 and 300 microl daily. Throughout each phase of Experiment 1, the larger reinforcer magnitude resulted in higher response rates and lower reinforcement rates. The peak of the interresponse-time distributions was at a lower value tinder the larger reinforcer magnitude. In Experiment 2, 3 pigeons responded under a DRL 20-s schedule in which reinforcer magnitude (1-s or 6-s access to grain) varied iron session to session. Higher response rates and lower reinforcement rates occurred tinder the longer hopper duration. These results demonstrate that larger reinforcer magnitudes engender less efficient DRL schedule performance in both rats and pigeons, and when reinforcer magnitude was held constant between sessions or was varied daily. The present results are consistent with previous research demonstrating a decrease in efficiency as a function of increased reinforcer magnituide tinder procedures that require a period of time without a specified response. These findings also support the claim that DRI. schedule performance is not governed solely by a timing process.     

Effects of a DRL contingency added to a fixed-interval reinforcement schedule

Following 30 days of reinforcement for the bar press response of two white rats on 30-sec fixed-interval (FI), a DRL component was added so that a minimal interresponse time (IRT) for the reinforced response, in addition to the FI variable, was necessary for reinforcement. Marked control over response rate by the superimposed DRL requirement was demonstrated by an inverse hyperbolic function as the DRL component was increased from 1 to 24 sec within the constant 30-sec FI interval. Interresponse time and post-reinforcement (post-S^R) “break” distributions taken at one experimental point (DRL = 24 sec) suggested that a more precise temporal discrimination was initiated by an S^R than by a response, since the relative frequency of a sequence of two reinforced responses appeared greater than that of a sequence of a non-reinforced response followed by a reinforced one. This latter finding was confirmed with new animals in a follow-up experiment employing a conventional 24-sec DRL schedule.     

A developmental study of timing behavior in 4 1/2- and 7-year-old children

The present study investigated effects of age and instructions on temporal regulations of behavior in children. In the first experiment 4 1/2-year-old and 7-year-old subjects were trained with a DRL (differential reinforcement of low rates) 5-s and a DRL 10-s schedule. Results demonstrate that age and timing performance are related. Seven-year-olds are more efficient than the 4 1/2-year-olds. A striking decline in the 4 1/2-year-old children's capacity to space responses was observed in the DRL 10-s schedule as compared to the DRL 5-s schedule. Analysis of individual performances suggests that the evolution of DRL performance between 4 and 7 years of age depends not only on the development of the capacity to delay responding but also on the acquisition of the ability to represent the reinforcement contingencies, that is, the temporal parameters of the task to oneself. In order to test this hypothesis a second experiment was conducted where instructions to wait between operant responses were given to a group of 4 1/2-year-old subjects at the beginning of a DRL 5-s and a DRL 10-s schedule. The results show that these instructions enhance DRL performance. By directing the 4 1/2-year-old subjects' attention to the temporal requirements of the task, instructions led to efficient performance and accurate timing of responses to the DRL schedule.     

The effect of physical restraint on behavior under the differential-reinforcement-of-low-rate schedule

Previous studies have identified and manipulated collateral behavior to assess the effect of collateral behavior on performance under the differential-reinforcement-of-low-rate (DRL) schedule. However, conclusions could not be applied to subjects not observed to engage in collateral behavior. The present study used a technique that prevented the occurrence of the types of collateral behavior typically observed in the pigeon. This technique did not require the identification of collateral behavior in the subjects. The exclusion of the types of collateral behavior typically observed in pigeons resulted in higher response rates and lower reinforcement rates under large DRL values but had no effect at lower DRL values. It was concluded that collateral behavior is necessary for low response rates and high reinforcement rates under large DRL values.     

Decreasing classroom misbehavior through the use of DRL schedules of reinforcement

In three studies, reinforcing low rates of responding reduced inappropriate behaviors. In the first study, the talking-out behavior of one TMR student was reduced when the teacher allowed 5 min of free time for a talk-out rate less than 0.06 per minute. In a second study, the talking-out behavior of an entire TMR class was reduced when reinforcement was delivered for a response rate less than 0.10 per minute. In a third study, successively decreasing DRL limits were used to reduce off-task verbalizations of an entire high school business class. In each case, the DRL procedure proved manageable for the teacher and successful in reducing misbehavior.     

Temporally spaced responding by pigeons: development and effects of deprivation and extinction

In the first five or six sessions on a DRL 20-sec schedule of reinforcement there developed a stable performance characterized by a relatively constant conditional probability of occurrence (IRTs/op) of interresponse times (IRTs) of durations greater than 5 or 6 sec. Extinction and the level of deprivation changed both the overall rate of responding and the form of the function relating the duration of an IRT to its value of IRTs/op. The value of IRTs/op decreased more rapidly for short than for longer IRTs, resulting in the emergence of a finer discrimination of IRT duration.