Variable-interval 30-s Research Articles

Punishment-induced resurgence

The phenomenon of extinction-induced resurgence is well established, but there is comparatively little experimental evidence for punishment-induced resurgence. Punishment-induced resurgence can by tested by contingent shocks following the alternative response. The purpose of Experiment 1 was to test whether low-intensity shocks, that do not decrease rate of reinforcement, result in resurgence. Four rats served as subjects. Rats were exposed to three sequential conditions: (a) variable-interval (VI) 30-s food delivery for a lever press (target response); (b) VI 30-s food delivery for a nose poke (alternative response) and extinction of the lever press; (c) VI 30-s reinforcement for a nose poke with superimposed VI 60-s shock delivery. In the final condition, shocks increased gradually from 0.1 to 0.5 mA. Experiment 2 evaluated whether an abrupt introduction of a high-intensity shock would result in resurgence. Three rats served as subjects and were exposed to three sequential conditions: (a) VI 30-s food delivery for a lever press; (b) VI 30-s food delivery for a nose poke and extinction of the lever press; (c) continued VI 30-s reinforcement for a nose poke with superimposed VI 60-s 0.6 mA shock delivery. Resurgence was observed in all subjects, including in situations in which rate of responding, but not rate of reinforcement, decreased. The present study provides additional evidence for punishment-induced resurgence, but future studies are warranted to determine the extent to which punishment can produce resurgence with or without decreases in rates of reinforcement.

Stimulus control of a social operant.

Three pigeon dyads were exposed to a two-component multiple schedule comprised of two tandem variable-interval 30-s interresponse time (IRT) > 3-s schedules in the presence of different stimuli. Pecks to keys by both pigeons of a dyad occurring within 500 ms of one another were required for reinforcement under one tandem schedule (the coordination component), and such coordinated responses were not required under the other (the control component). The terminal link of each schedule ensured that the reinforced coordination response was an IRT > 3 s. Rates of coordinated IRTs > 3 s and total rates of coordinated responses (composed of IRTs > 3 s and IRTs ≤ 3 s) were higher in the coordination components than in either of two different control components in which coordination was not required for reinforcement. This difference in coordinated responses in the presence and absence of the coordination requirement under stimulus control transitorily deteriorated and then was reestablished when the relation between the stimulus and the coordination contingency or its absence was reversed. The results show coordinated responding to function as a discriminated social operant.

Resurgence increases with repetition

Resurgence refers to a behavioral process in which a recent response is extinguished (or reinforcement conditions worsen) and a previously extinguished response recurs. In previous research, resurgence has been reliably produced when the resurgence procedure is repeated. Changes in the degree of increase of the resurging response across iterations of the procedure have been inconsistent, however, with some studies showing increases and some showing no changes or decreases in resurgence magnitude. The present study examined the nature of resurgence across repeated iterations of the conventional resurgence procedure by exposing four pigeons to the resurgence procedure six times in succession. In the first condition of the resurgence procedure, pecks on one key (e.g., the left) were reinforced under a variable-interval (VI) 30-s schedule. In the second condition pecks on that key were extinguished, and pecks on another key (e.g., the right) were reinforced under the same schedule. In the final condition there were no programmed consequences for either response. Resurgence was observed in 21 of 24 opportunities (87.5%). Iteration-over-iteration increases in resurgence were observed in 15 of 20 opportunities (75.0%), and this increase was found to be statistically significant. These findings demonstrate that, under certain conditions, resurgence generally increases in magnitude with repeated exposure to the procedures that generate it.

Resurgence during transitions from variable- to fixed-interval schedules

The effects of local periods of extinction on resurgence following transitions from variable-interval (VI) to fixed-interval (FI) schedules were studied using four pigeons exposed to a within-session resurgence procedure. Each session was divided into a Training (T) Alternative-Reinforcement (AR), and Resurgence Test (RT) phase. During the T phase, key pecking was reinforced under a VI 60-s schedule on one key. In the AR phase, responses reinforced in the T phase were extinguished, while responses to a different key were reinforced under a VI 90-s schedule. Next, responding to the same key that produced reinforcers in the AR phase was reinforced according to four different RT conditions: RT phase I (FI 90 s), RT phase II (FI 180 s), RT phase III (FI 45 s), or RT phase IV (extinction). The frequency of resurgence generally was an inverse function of the rate of reinforcement in the RT phase. Resurgence occurred less often when reinforcers were delivered under the FI 45-s schedule and more often under leaner schedules in the RT phase, peaking under extinction. The results show that resurgence may occur during local periods of extinction, with larger and more consistent effects occurring when the rate of reinforcement in the RT condition is leaner than it was during the preceding AR phase.

Does DRO type matter?: Cycle versus resetting contingencies in eliminating responding

Following lever-press training on variable-interval 30-s schedules, rats were exposed to three types of schedules designed to eliminate lever pressing. The first two were variations on what is called a differential-reinforcement-of-other-behavior (DRO, “zero rate”, or [target response] omission schedule) schedule. Under both variations, reinforcers were scheduled to occur in different conditions after either fixed or variable inter-reinforcer intervals (IRIs). Under one variation each lever press reset the time interval (i.e., “resetting DRO”) and under the other a reinforcer delivery scheduled at the end of an IRI was cancelled by the first response during the IRI (i.e., “cycle DRO”). In another condition reinforcers were delivered independently of responding after fixed or variable time periods. Each of the DRO procedures reduced response rates quickly and to near zero across ten sessions. The time schedules also reduced responding, albeit at a slower rate. The results extend the analogy of omission training to freeoperant avoidance to shock-deletion avoidance schedules.

An evaluation of resurgence in mice

Owing in part to the implications of resurgence for issues surrounding human health and adaptive problem solving, a substantial amount of laboratory research has been dedicated to understanding why this form of relapse occurs and what factors affect it. This research, however, has never been extended to mice, leaving unknown the specific experimental parameters that are appropriate for studying resurgence in this species. Two experiments were conducted in which mice were exposed to a three-phase resurgence preparation in a multiple-baseline-across-subjects design. In Phase 1, pressing a target lever produced food according to a variable-interval 15-s schedule. In Phase 2, target-lever pressing was extinguished, and nose poking produced reinforcement according to either a variable-interval 15-s (Experiment 1) or fixed-ratio 1 (Experiment 2) schedule. Finally, alternative reinforcement was suspended to test for resurgence. Lever pressing relapsed for one of four mice in Experiment 1, but all four mice demonstrated relapse in Experiment 2. Thus, relatively dense schedules of alternative reinforcement may be required to reliably study resurgence of previously reinforced responding in mice. These findings are instructive for researchers who are interested in studying resurgence of mice’s behavior and further demonstrate the cross-species generality of this form of relapse.

Resurgence and downshifts in alternative reinforcement rate.

Resurgence refers to an increase in a previously suppressed target behavior with a relative worsening of conditions for a more recently reinforced alternative behavior. This experiment examined the relation between resurgence and the magnitude of a reduction in the rate of reinforcement for the alternative behavior. Groups of both male and female rats initially pressed a target lever for food on a variable-interval (VI) 30-s schedule. In a second phase, responding to the target lever was extinguished for all groups and pressing an alternative lever was reinforced on a VI 10-s schedule. Next, the rate of reinforcement for alternative behavior was reduced differentially across groups by arranging extinction, VI 80-s, VI 40-s, VI 20-s, or continued VI 10-s reinforcement. Target responding increased as an exponential function of the magnitude of the reduction in alternative reinforcement rates. With the exception that males appeared to show higher rates of target responding in baseline and higher rates of alternative responding in other phases, the overall pattern of responding across phases was not meaningfully different between sexes. The pattern of both target and alternative response rates across sessions and phases was well described quantitatively by the Resurgence as Choice in Context model.

Local constraint of the contingent response controls rates of wheel-running and lever-pressing on an interval schedule of wheel-running reinforcement

Three experiments assessed whether changes in rates of wheel running and lever pressing on a schedule of wheel-running reinforcement were controlled by local or overall constraint of the contingent response. In Experiment 1 rats responded on a response-initiated variable interval 15-s schedule with wheel running as reinforcement. Overall constraint (total revolutions by session) was held constant at 600 revolutions while local constraint (revolutions per reinforcement) varied from 5 to 60 revolutions. Results showed that rates of wheel running and lever pressing decreased as local constraint decreased. In Experiment 2, rats responded on the same schedule, but local constraint (revolutions per reinforcement) was held constant at 10 revolutions. Overall constraint (total revolutions) was varied from 100 to 800 revolutions. Results showed no systematic changes in rates of wheel running and lever pressing with variation in overall constraint. In Experiment 3, rats responded on the same VI schedule for 30 revolutions as reinforcement. A 4.5-s interruption during the wheel-running reinforcement (30 revolutions) occurred after 2, 5, 10, and 15 revolutions as a manipulation of local constraint. Results showed that with overall constraint (total revolutions) and total reinforcement held constant, rates of wheel running before the interruption and overall lever-pressing rates varied in a bitonic relationship with local constraint. Comparison of the results across experiments demonstrates that local constraint of contingent wheel running controls the rate of wheel running and the rate of instrumental responding for wheel-running reinforcement.

Repeated Operant Response Resurgence with a Peak-Interval Procedure

Resurgence is most often defined as the recurrence of previously reinforced behavior during extinction of another, more recently reinforced behavior. It provides a framework for deciphering the origin of operant responses, studying the effects of historical variables, and understanding socially relevant behaviors. The present manuscript proposes a novel procedure that incorporates the peak-interval procedure, typically used to examine temporal control, to examine resurgence repeatedly. Three experimentally naive Long Evans rats were trained using a concurrent variable-interval (VI) 30-s fixed-interval (FI) 30-s schedule, with each schedule programmed on a different lever. After stability was reached, responding under the VI 30-s schedule was extinguished for 15 sessions. A peak-interval procedure then was employed to examine resurgence of the previously VI responding. The peak-interval procedure consisted of FI 30-s trials intermixed with 300-s peak trials, each separated by 20-s blackouts. Resurgence of operant responding was obtained and examined within and across sessions.

Female rats express habitual behavior earlier in operant training than males.

Habitual behavior can be advantageous by increasing the availability of cognitive resources for use in other tasks. However, habitual behaviors are problematic when they are coopted to prolong the maladaptive responding present in several psychopathologies such as substance abuse, dysregulated fear responding in posttraumatic stress disorder, and obsessive-compulsive disorder. Although sex differences exist in the occurrence or progression of these psychopathologies, there are no studies that compare the development of habitual behavior systematically in male and female animals. In the present study, male and female rats were identically trained on a variable interval 30-s (VI 30-s) schedule of reinforcement to nose-poke for sucrose pellet reinforcers. Subsequently, the sucrose was devalued in one half of the animals by pairing its presentation with injections of lithium chloride (LiCl) to induce nausea, thus conditioning a taste aversion. Habitual behavior was operationalized as continued operant responding in an extinction test following devaluation of the sucrose reinforcer. Successful devaluation was confirmed with both a consumption and reacquisition test. Given identical training to 240 sucrose pellets, female rats demonstrate habitual behavior whereas male rats remain goal-directed. Additionally, females are habitual after 200 or 160 reinforcers earned on a VI 30-s schedule, but remain goal-directed at 120 and 80 reinforcers on this schedule. These data suggest that behavioral flexibility may be compromised in female rats compared to males due to accelerated habit formation in females. These results are important because sex differences are present in several psychopathologies, which may be related to differences in the development of habitual behavior. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Instrumental lever pressing for wheel running is a bitonic function of wheel revolutions per reinforcement: Effects of constraint and automatic reinforcement

The current study investigated the relationship between wheel-running reinforcement and operant lever pressing when an opportunity to run is defined by the number of wheel revolutions rather than duration of wheel access. Twelve female Long-Evans rats responded on response-initiated variable interval 15-s schedules for the opportunity to run for 1, 3, 5, 10, 20, 30, or 40 revolutions. Half the rats received an ascending order of revolutions/reinforcement; the other half, received a descending order. Results showed that wheel-running and lever-pressing rates were described by a bitonic relationship with revolutions/reinforcement, initially rising then falling, as revolutions/reinforcement increased. Long postreinforcement pause (PRP) durations occurred with few revolutions, short PRPs with an intermediate number, and long PRPs again with a high number of revolutions; thus, PRP showed an inverted U-shaped function. Rather than a reinforcement-magnitude interpretation, our findings suggest that number of revolutions/reinforcement (or duration of wheel access) be conceptualized as constraint on an automatically-reinforcing behavior (wheel running). Specifically, we propose that the automatic-reinforcement value of contingent wheel running varies with its rate of occurrence, which causes instrumental lever-pressing rates to vary with wheel-running rates. The current analysis of constraint and the automatic reinforcement of the contingent behavior is shown to further extend the response-deprivation hypothesis to wheel-running reinforcement.

Punishment and the potential for negative reinforcement with histamine injection.

The present study examined punishment of responding with histamine injection, and its potential to generate avoidance of punishment. Sprague-Dawley rats were trained under concurrent schedules in which responses on one lever (the punishment lever) produced food under a variable-interval schedule, and under some conditions intermittent injections of histamine, which suppressed behavior. Responses on a second (avoidance) lever prevented histamine injections scheduled on the punishment lever. After stabilization of punished responding, a variable-interval 15-s schedule of cancellation of histamine (avoidance) was added for responding on the second/avoidance lever, without subsequent acquisition of responding on that lever. Progressive decreases in the length of the punishment variable-interval schedule increased suppression on the punishment lever without increases in response rates on the avoidance lever. Exchanging contingencies on the levers ensured that response rates on the avoidance lever were sufficiently high to decrease the histamine injection frequency; nonetheless response rates on the avoidance lever decreased over subsequent sessions. Under no condition was responding maintained on the avoidance lever despite continued punishing effectiveness of histamine throughout. The present results suggest that avoidance conditioning is not a necessary condition for effective punishment, and confirm the importance of empirical rather than presumed categorization of behavioral effects of stimulus events.

Proprioceptive stimuli and habit formation: Interresponse time mediated behavior in CD-1 mice

The consolidation of behavioral sequences into relatively ballistic habits is thought to involve the formation of stimulus – response associations. Typically, the stimuli in these associations are assumed to be exteroceptive, i.e., external to the organism. However, responses, themselves, also possess stimulus properties that can mediate behavior. Indeed, these “proprioceptive cues” have long been hypothesized to underlie habit formation (Hull, 1934a, 1934b). One such stimulus involves the time durations between responses – a stimulus termed interresponse time (IRT). We hypothesize that IRTs can come to serve as stimuli that differentially control response elements during habit formation. To examine this hypothesis we report on two experiments that asked whether CD-1 mice utilize IRTs to structure behavior in a two-choice environment. In experiment 1, eight mice were exposed to a free-operant concurrent variable-interval (VI) 30-s VI 60-s reinforcement schedule. We found that switch and stay responses were differentially correlated with IRT durations. In Experiment 2 we directly and differentially reinforced stay/switch responses based on IRT durations in a two-lever procedure. For four of the subjects, the probability of receiving reinforcement after switch responses was proportional to IRT duration. For five of the subjects, these reinforcement probabilities were inversely proportional to IRT duration. Regardless, all of our subjects learned to emit IRT-mediated switching behavior that matched the reinforcement contingencies. Together, Experiments 1 and 2 provide the first evidence of which we are aware that IRTs can come to control sequential choice behavior in mice.

The role of response force on the persistence and structure of behavior during extinction.

Behavior Momentum Theory has emerged as a prominent account of resistance to change in both basic and applied research. Although laboratory studies often define precise, repeatable responses, application research often deals with response classes that may vary widely along a number of dimensions. In general, Behavior Momentum Theory has not addressed how response dimensions impact resistance to change, providing an opportunity to expand the model in new directions. Four rats pressed a force transducer under a multiple variable interval (VI) 60-s VI 60-s schedule of reinforcement. In one component, responses satisfied the schedule only if the response force fell within a "low" force band requirement; responses in the other schedule were required to satisfy a "high" force band. Once responding stabilized, extinction was programmed for three sessions. Then, the procedures were replicated. The results showed that response force came under discriminative control, but force requirements had no impact on resistance to extinction. In a follow-up condition, the schedule was changed to a multiple VI 30-s VI 120-s schedule and the low-force band operated in both components. The results showed that behavior maintained by the VI 30-s schedule was generally more resistant to extinction. A secondary analysis showed that force distributions created under baseline maintained during extinction. Overall, the results suggest that differential response force requirements prevailing in steady state do not affect the course of extinction.

Multiple schedules, off-baseline reinforcement shifts, and resistance to extinction.

Resistance to extinction in a target multiple-schedule component varies inversely with the rate of reinforcement arranged in an alternative component during baseline. The present experiment asked whether changing the reinforcer rate in an alternative component would impact extinction of target component responding if those changes occurred in an off-baseline phase during which the target component was never experienced. Pigeons' key pecking was studied in three types of conditions, and each condition consisted of three phases. In Phase 1, pecking produced food in the target and alternative components of a multiple schedule according to variable-interval 60-s schedules. In Phase 2, the alternative-component stimulus was presented alone in a single schedule. Pecking during this phase produced the same reinforcer rate as in baseline in the Control condition, a higher rate of food (variable-interval 15 s) in the High-Rate condition, or was extinguished in the Extinction condition. Extinction of target- and alternative-component key pecking then was assessed in a multiple schedule during the final phase of each condition. Resistance to extinction of target-component key pecking was the same between the Control and High-Rate conditions but lower in the Extinction condition. These findings are discussed in terms of discrimination and generalization processes.

Stimuli previously associated with reinforcement mitigate resurgence

Resurgence refers to the recurrence of an extinguished target behavior following subsequent suspension of alternative reinforcement. Delivery of reinforcers during extinction of alternative behavior has been shown to mitigate resurgence. The present experiment aimed to determine whether delivering stimuli associated with reinforcers during resurgence testing similarly mitigates resurgence. Three groups of rats pressed target levers for food according to variable-interval 15-s schedules during Phase 1. In Phase 2, lever pressing was extinguished, and an alternative nose-poke response produced alternative reinforcement according to a variable-interval 15-s schedule. Food reinforcement was always associated with illumination of the food aperture and an audible click from the pellet dispenser during Phases 1 and 2. Phase 3 treatments differed between groups. For one group, nose poking continued to produce food and food-correlated stimuli. Both of these consequences were suspended for a second group. Finally, nose poking produced food-correlated stimuli but not food for a third group. Target-lever pressing resurged in the group that received no consequences and in the group that received only food-correlated stimuli for nose poking. Resurgence, however, was smaller for the group that received food-correlated stimuli than for the group that received no consequences for nose poking. Target-lever pressing did not increase between phases in the group that continued to receive food and associated stimuli. Thus, delivery of stimuli associated with food reinforcement after suspension of food reduced but did not eliminate resurgence of extinguished lever pressing. These findings contribute to potential methodologies for preventing relapse of extinguished problem behavior in clinical settings.

Resurgence of response duration in human participants

Previously reinforced responses can reappear when reinforcement is withdrawn from current responding. This is known as resurgence. Although resurgence of response topography, spacing, and patterns over time has been demonstrated, there is no evidence of resurgence of response duration. This experiment explored resurgence of response duration in humans. In Phase 1 a multiple schedule of reinforcement with two components was used. In each component a chained variable-interval 30s, variable-ratio 3 schedule was implemented. In the terminal link of the chained schedule, response durations between 0.1 and 0.5s were reinforced during one component, and between 2 and 8s in the other component. In Phase 2, response requirement during the terminal link of the chained schedule was inverted between components relative to Phase 1. In Phase 3 the chained schedule was changed to a variable-interval 30-s, extinction 30s. Resurgence of the durations trained during Phase 1 was observed. It was concluded that duration is a response dimension that reappears during extinction.

INTERAÇÕES COMPORTAMENTAIS EM ESQUEMA MÚLTIPLO UTILIZANDO O JATO DE AR QUENTE (JAQ) COMO ESTÍMULO PUNIDOR

Interação comportamental é um fenômeno que pode ocorrer em esquemas múltiplos, em que a taxa de respostas em um componente pode mudar em função de alteração do esquema de reforçamento ou de punição no segundo componente. Interações comportamentais podem ocorrer quando há utilização de contingências apetitivas ou aversivas, como punição. Com relação às contingências punitivas, existem dados conflitantes na literatura sobre a produção de contraste ou indução com não humanos, utilizando majoritariamente choque elétrico como estímulo punidor. O objetivo deste estudo foi verificar se ocorreria algum tipo de interação comportamental em esquemas múltiplos, utilizando o jato de ar quente (JAQ) como estímulo punidor. Dezesseis ratos albinos foram expostos às fases: Pré-Punição, Punição e Pós-Punição. Nas três fases vigorou um esquema múltiplo com dois componentes (claro e escuro). O esquema de reforçamento em vigor em ambos os componentes foi intervalo variável 30s (VI 30) para respostas de pressão à barra, em todas as fases. Na fase punição, o JAQ foi administrado contingente a cada resposta de pressão à barra no componente claro para metade dos sujeitos, e no escuro para a outra metade. Ocorreu indução negativa no componente não punido, para todos os sujeitos, principalmente nas sessões iniciais; ao longo das sessões, ocorreu recuperação na taxa nesse componente para todos os sujeitos, resultando em ocorrência tardia de contraste positivo para três dos sujeitos. A produção de contraste parece estar relacionada ao número de sessões de exposição ao punidor.Palavras-chave: interação comportamental, punição, contraste, indução.

The effect of lever height on the microstructure of operant behavior

The effect of lever height on the temporal organization of reinforced lever pressing was examined. Lever pressing was reinforced on a variable-interval 30-s schedule in rats, with lever height manipulated across six successive conditions. Parameters of the organization of responses in bouts (bout length distribution, bout-initiation rate, within-bout rate, and sequential dependency) were estimated. These estimates revealed (1) a qualitative change in the distribution of IRTs and their sequential dependency when the lever was too high, (2) a mixture of geometrically-distributed bout lengths at all lever heights, and (3) longer bouts at lower and intermediate lever heights. In accordance with previous data, these findings suggest that lower and intermediate lever heights favored lever pressing with longer bout lengths, faster bout initiation, faster within-bout responding, and more sequentially dependent timing. These results underscore the disociability of motoric capacity in operant performance, and may reflect the influence of the body size on the temporal organization of the operant.

The effects of 100 dB 1‐kHz and 22‐kHz tones as punishers on lever pressing in rats

Aversive control is an important yet understudied process of learning. One reason aversive control may be relatively understudied is ethical concerns about painful stimuli (e.g., electric shock). High decibel broad-band noise and 22-kHz vocalizations both demonstrably affect rodent behavior while not necessarily being painful. The goal of this study was to determine if 100-dB 22-kHz-pure tones were differentially more effective in reducing operant response rates in rats. We examined whether 22-kHz pure tones would function as aversive stimuli, specifically as positive punishers. The effects of response-dependent as well as continuously presented 22-kHz and 1-kHz tones on rate of response maintained by variable interval 30-s food deliveries were assessed across several conditions. We found that response rates were lower when tones were presented response dependently than when tones were presented continuously throughout a session. We also found that the lower response rates obtained with response-dependent 22-kHz tones were not significantly different from response rates obtained with response-dependent 1-kHz tones. The primary conclusion of this experiment is that both 1-kHz and 22-kHz tones functioned as punishers, but that the 22-kHz tones were not differentially more effective in reducing response rate.