Fixed-interval Schedule Research Articles

Operant Wheel Running on a Fixed Interval Schedule: Does Contingent Sucrose Reinforcement Increase Running through a Schedule-Induction or Reinforcement Effect?

Operant Wheel Running on a Fixed Interval Schedule: Does Contingent Sucrose Reinforcement Increase Running through a Schedule-Induction or Reinforcement Effect?

Reinforcing and adverse observable effects of nicotine and minor tobacco alkaloids in squirrel monkeys

The most prevalent psychoactive chemical in tobacco smoke is nicotine, which has been shown to maintain tobacco consumption as well as cause acute adverse effects at high doses, like nausea and emesis. Recent studies in laboratory animals have suggested that many non-nicotine constituents of tobacco smoke (e.g., minor tobacco alkaloids) may also contribute to tobacco’s overall reinforcing and adverse effects. Here, we used intravenous (IV) self-administration (n = 3) and observation (n = 4) procedures in squirrel monkeys to, respectively, compare the reinforcing and adverse observable effects of nicotine and three prominent minor tobacco alkaloids, nornicotine, anatabine, and myosmine. In self-administration studies, male squirrel monkeys were trained to respond under a second-order fixed-interval schedule of reinforcement and dose-effects functions for nicotine and each of the minor tobacco alkaloids nornicotine, anatabine, and mysomine were determined. Observation studies were conducted in a different group of male squirrel monkeys to quantify the ability of nicotine, nornicotine, anatabine, and mysomine to produce adverse overt effects, including hypersalivation, emesis, and tremors. Results show that nicotine and to a lesser extent nornicotine were readily self-administered, whereas anatabine and myosmine were not. In observation studies, all minor tobacco alkaloids produced adverse observable effects that were either comparable or more pronounced than nicotine. Collectively, the present results showing that nicotine and the minor tobacco alkaloids nornicotine, anatabine, and myosmine produce differential reinforcing and acute adverse observable effects in monkeys provides further evidence that these constituents may differently contribute to the psychopharmacological and adverse effects of tobacco consumption.

Active and passive waiting in impulsive choice: Effects of fixed-interval and fixed-time delays.

Behavioral interventions to improve self-control, preference for a larger-later (LL) reward over a smaller-sooner (SS) reward, involve experience with delayed rewards. Whether they involve timing processes remains controversial. In rats, there have been inconsistent results on whether timing processes may be involved in intervention-induced improvements in self-control. Interventions that improved self-control with corresponding timing improvements used fixed-interval (FI) delays, whereas interventions that failed to find corresponding timing improvements used fixed-time (FT) delays. The FI schedule includes a response contingency (active waiting), whereas the FT schedule delivers reward automatically (passive waiting). The present study compared the effects of FI and FT schedules in interventions and impulsive choice tasks to evaluate effects on self-control and timing behavior. The impulsive choice task evaluated preference for an SS option (one pellet after 10-, 15-, 20-, 25-, and 30-s delays) versus an LL option (two pellets after a 30-s delay). The intervention task included forced-choice SS (one pellet after 10 s) and LL (two pellets after 30 s) sessions under FI or FT schedules. FI schedules produced greater sensitivity to SS delay in the impulsive choice task. Both FI and FT interventions increased LL choices. Following choice testing, temporal bisection and peak interval tasks revealed better timing precision for rats with an FI delay experience. Overall, the FI choice contingency was associated with improved temporal attention and timing precision.

Comparison of Fixed-Ratio and Fixed-Interval Schedules of Reinforcement within the Treatment of Escape-Reinforced Problem Behavior

Comparison of Fixed-Ratio and Fixed-Interval Schedules of Reinforcement within the Treatment of Escape-Reinforced Problem Behavior

Effects of contingent and noncontingent reinforcement on the emotional behavior of domestic dogs (Canis familiaris)

Intermittent schedules of reinforcement are frequently used in dog training. During fixed-time (FT) schedules, reinforcement delivery is time-based and response-independent. In contrast, during fixed-interval (FI) schedules, a response produces a reinforcer if a certain amount of time has elapsed since the last reinforcer was delivered (i.e., FI schedules are time-based and response-dependent). FT schedules are typically used in noncontingent-reinforcement interventions with the aim of decreasing an undesired behavior. Although the effectiveness of these interventions has been reliably shown with human and nonhuman animal learners, little is known about the emotional behavior that is related to these contingencies. In the present study, the target behavior (stepping on a mat) of six dogs was initially trained (shaped) and maintained on a FI 15s schedule. In addition, dogs were exposed to a FT 15s schedule, a combination of FT 15s and FI 15s schedules, and an extinction-only condition (no reinforcement was delivered for the target response). We found that rates of emotional responses (e.g., lip/nose licking, vocalizing) varied in prevalence across dogs and phases. Although lip/nose licking was displayed in high rates across all dogs and phases, it was generally lower in baseline and extinction phases. This suggests that these phases produced less frustration-related behavior. The effect-size calculations for dogs engaging in pacing, sneezing, and vocalizing underscored the varied prevalence of the behaviors across phases and dogs and yielded mostly small- to medium-size effects. These results are especially relevant for the training of companion and working dogs and their well-being during training sessions. Future research should continue investigating emotional behavior in dogs across various schedules of reinforcement (e.g., variable schedules).

Cisplatin decreases voluntary wheel-running activity but does not impair food-motivated behavior in mice

Cisplatin is a chemotherapeutic agent that is still commonly used to treat solid tumors. However, it has several toxic side effects due in large part to the mitochondrial damage that it induces. As this mitochondrial damage is likely to result in a decrease in the amount of metabolic energy that is available for behavioral activities, it is not surprising that fatigue develops in cancer patients treated with cisplatin. The present preclinical study was initiated to determine whether the detrimental effects of cisplatin were more pronounced on physical effort requiring a lot of energy versus effort that not only requires less energy but also procures energy in the form of food. For this purpose, mice were either trained to run in a wheel or to work for food in various schedules of food reinforcement before being treated with cisplatin. The experiments were carried out only in male mice as we had already reported that sex differences in cisplatin-induced neurotoxicities are minimal. Cisplatin was administered daily for one cycle of five days, or two cycles separated by a five-day rest. As observed in previous experiments, cisplatin drastically reduced voluntary wheel running. In contrast, when cisplatin was administered to food-restricted mice trained to work for a food reward in a progressive ratio schedule or in a fixed-interval schedule, it tended to increase the number of responses emitted to obtain the food rewards. This increase was not associated with any change in the temporal distribution of responses during the interval between two reinforcements in mice submitted to the fixed interval schedule of food reinforcement. When cisplatin was administered to food-restricted mice trained in an effort-based decision-making task in which they had to choose between working for a grain pellet with little effort and working for a preferred chocolate pellet with more effort, it decreased the total number of responses emitted to obtain food rewards. However, this effect was much less marked than the decrease in wheel running induced by cisplatin. The decrease in the effort invested in the procurement of food rewards was not associated with any change in the relative distribution of effort between low reward and high reward during the time course of the test session. These findings show that cisplatin decreases energy-consuming activities but not energy-procuring activities unless they require a choice between options differing in their cost-benefit ratio. Furthermore, they indicate that the physical dimension of fatigue is more likely to develop in cisplatin-treated individuals than the motivational dimension of fatigue.

A behavioral timing intervention upregulates striatal serotonergic markers and reduces impulsive action in adult male mice

Many studies support the hypothesis that time-based interventions reduce impulsive behavior in rodents. However, few studies have directly assessed 1) how such interventions affect impulsive action rather than impulsive choice, 2) if intervention effects differ by sex, and 3) how time-based interventions affect neurochemistry in regions mediating decision-making and reward. Thus, we assessed how a fixed-interval (FI) intervention initiated during late adolescence and extending into adulthood affected dopaminergic and serotonergic analytes in the frontal cortex and striatum and subsequent impulsive action in adult male and female mice. Beginning on postnatal day (PND) 45, mice were either trained on a progressive series of FI schedules (FI 20, 40, & 60 s) or remained in the home cage. Following the intervention, increases in striatal serotonergic analytes were found in FI-exposed males and females (n = 8/sex/group) with few changes found in the frontal cortex. Impulsive action was assessed in the remaining mice (n = 10/sex/group) using a fixed-ratio waiting-for-reward (FR-wait) task in which completion of an FR-25 component initiated a “free” pellet component in which pellets were delivered at increasing intervals according to a fixed delay increment that varied across sessions. Responses reset the additive delay and initiated a new FR-25 component. FI-exposed males, but not females, showed fewer delay resets and no-wait resets relative to control mice. Importantly, FI-exposure did not affect discrimination reversal performance in either sex. These data suggest that time-based interventions may reduce impulsive action in addition to impulsive choice perhaps with increased male sensitivity. Additionally, time-based interventions appear to operate through striatal serotonergic augmentation.

Spatial organization of rat’s behavior in a situation with three optional lever-pressing responses under continuous and fixed-interval schedules of food

We assessed spatiotemporal distribution of behavior as a function of the spatial and temporal arrangement of food delivery. Eight food-deprived rats were exposed in an extended experimental chamber to a continuous reinforcement schedule (CRf) or to a fixed interval (FI) 30 s, with three levers contiguous to food dispenser or placed on separate panels. Responses on any of the levers were equally operative on the ongoing schedule. All rats moved mainly near to dispenser and levers when these were contiguous, under both, CRf and FI schedules, although distribution of responses on different levers was more variant under FI than under CRf. With separate levers, rats traveled through a larger area of the experimental space, especially under FI. Distribution of responses showed more variation under FI than under CRf schedule. Under FI, response patterns consisted in a post-meal pause followed by an acceleration towards the next food. Findings are discussed in the context of studies in which have been reported inconsistent patterns under FI schedules when are manipulated the number of operanda, dispensers, and their locations. It is highlighted the relevance of continuous analysis of rats’ displacement, to account for the configuration of response patterns observed in this study.

Sustainable society via complexity analysis of the relationship between virtual game reward mechanism and addiction

As of January 2021, nearly 60% of the global population are active internet users, which means that the current social pattern presents an integration of virtual and reality under the rapid progress of urbanization. Current solutions for sustainable cities and society should combined the factors of virtual world in era of Industry 4.0. Multiplayer Online Games (MOGs) are increasingly used as an experimental environment for social science. However, the premise is that there must be enough game players to maintain virtual ecology. Therefore, we use Nova Empire to perform a complexity analysis of the relationship between virtual game reward mechanism and addiction. Specifically, we have tracked 1,800 players for 3 years, which verifies that random reward is easier to cultivate player's habits than fixed reward. Furthermore, we divide the reward into fixed interval schedule, fixed ratio schedule and random schedule. Gaming data of 3,670 players in September 2021 are used for correlation and regression analysis, which perform fine-grained analyses of the significance of different reward on online time in different stages. Finally, a series of suggestions are proposed for policy maker to promote sustainability based on the complexity analysis results and consistency of Nova Empire with real society.

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.

Assessment of the ‘timing’ function of schedule-induced behavior on fixed-interval performance.

It has been suggested that schedule-induced behaviors allow organisms to adapt better to temporal regularities of the environment. The main goal of the present study was to observe the effect of schedule-induced drinking (SID) on the performance in fixed-interval (FI) schedules. Rats were exposed to a FI 15-, 30-, or 60-s food reinforcement schedule, and only half of them had access to water in the experimental chamber. Rats with access to water developed SID, which occurred in the first part of the interval, regardless of the FI value, and was followed by an increase in lever pressing rate. There were no substantial differences in the quantitative measures of timing between groups that had or did not have access to water, except for the rats in the FI 15-s group with access to water, who showed longer postreinforcement pauses, possibly attributable to competition between SID and lever pressing. SID did not manifest the scalar property, contrary to lever pressing, but it is proposed that behaviors are displayed serially until the last behavior before the target operant response becomes a discriminative stimulus for that behavior. It is not assumed that the purpose of schedule-induced behaviors is to aid timing, but the development of behavioral patterns might determine the performance of organisms on temporal tasks. Additionally, in some cases competition between responses might exert more control on when the operant behavior occurs than timing. Timing seems to consist in the temporal organization of available behaviors that leads to a specific behavior occurring at a specified time, a single characteristic that typically had come to indicate accurate timing. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Comparative cognition-Conceptual and methodological advancements.

This special issue originally placed a Call for Papers that emphasized the importance of "Conceptual and Methodological" advances in the field of Comparative Cognition. Represented here is a collection of 14 papers that helps to display some of the diversity of ideas and approaches within this flourishing research area. The first paper in this issue, by Gazes and Lazareva (2021), discusses transitive inference learning from the perspectives of: identifying the problems of contextual variables in studying different species; whether associative processes can or cannot fully account for the behavior and, if not, what alternative representational mechanisms might be at work; and, finally, how ecological considerations may support comparative research by suggesting novel theoretical and empirical questions. The next paper, by Loy et al. (2021) investigates questions related to the complexity of learning in invertebrate species, single-celled organisms, and plants. The paper by Rawlings et al. (2021) reviews the literature on cumulative cultural evolution, primarily in nonhuman primate species, and critically evaluates the importance of identifying the essential conceptual and methodological issues in what many have deemed to be a uniquely human form of behavior. The paper by Goto and Watanabe (2021) explores whether the mouse visual system is sensitive to Gestalt principles, using operant discrimination learning tasks similar to those used previously to document Gestalt processing in chimpanzees and humans. Qadri and Cook (2021) use the innovative approach of "adaptive genetic algorithms" to assess the relative importance of different features of a stimulus in controlling organisms' discrimination learning performance. Wittek et al. (2021) introduce a novel method for studying the importance of visual accumulation processes in pigeons when information is presented to a single hemisphere at a time. The paper by Cowie et al. (2021) focuses on a misallocation model of two-step sequence learning in young children and explores from a behavioranalytic viewpoint the implications of assuming that reinforcement might be misattributed to a misremembered response at the beginning of the behavioral sequence. The paper by López-Tolsa and Pellón (2021) explores whether the opportunity to display schedule-induced drinking as an early response within a behavioral sequence might alter the accuracy of temporal control in different-length fixed-interval schedule tasks with rats. Crystal (2021) reviews the literature examining episodic memory in nonhuman species and considers a variety of criteria and methods thought to be crucial for establishing empirical evidence for episodic memory in nonhumans, in general, and rats, in particular. Vila et al. (2021) discuss the use a novel 'hide-and-seek' task in preschool age children to study episodic-like memory; their work illustrates how memory dynamics can change over time in a manner not very unlike what has been demonstrated in other nonhuman research paradigms. The paper by Krichbaum et al. (2021) discusses some of the methodological difficulties one faces in studying spatial cognition in canines. The paper by Castro et al. (2021) uses a complex categorization learning task in which different sets of display features are diagnostic, or not, of category mastery depending upon context. The paper by Vernouillet et al. (2021) explores the formation of same/different concept learning in two species of corvids (pinyon jays and California scrub jays). The final paper, by Lazarowski et al. (2021) examines the possibility of abstract same/different learning in canines using a trial-unique training matching-to-sample procedure with olfactory stimuli. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Stimulus generalization of behavioral history: Interspecies generality and persistence of generalization gradients.

Four pigeons were exposed to a tandem variable-interval (VI) fixed-ratio (FR) schedule in the presence of a 50-pixel (about 15 mm) square or an 80-pixel (about 24 mm) square and to a tandem VI differential-reinforcement-of-low-rate (DRL) schedule when a second 80-pixel or 50-pixel square was present. The values of the VI and FR schedules were adjusted to equate reinforcement rates in the two tandem schedules. Following this, a square-size continuum generalization test was administered under a fixed-interval (FI) schedule or extinction. In the first testing session, response frequency was a graded function of the similarity of the test stimuli to the training stimuli for all pigeons. These systematic generalization gradients persisted longer under the FI schedule than under extinction.

Effects of pre‐operant running and sucrose concentration on operant wheel running on a fixed interval schedule of reinforcement

Prior research proposed that temporal control over the pattern of operant wheel running on a fixed interval (FI) schedule of sucrose reinforcement is a function of automatic reinforcement generated by wheel running and the experimentally arranged sucrose reinforcement. Two experiments were conducted to assess this prediction. In the first experiment, rats ran for different durations (0, 30, 60, and 180 min) prior to a session of operant wheel running on a FI 120-s schedule. In the second experiment, the concentration of sucrose reinforcement on a FI 180-s schedule was varied across values of 0, 5, 15, and 25%. In Experiment 1, as the duration of pre-operant running increased, the postreinforcement pause before initiation of running lengthened while wheel revolutions in the latter part of the FI interval increased. In Experiment 2, wheel revolutions markedly increased then decreased to a plateau early in the FI interval. Neither manipulation increased temporal control of the pattern of wheel running. Instead, results indicate that operant wheel running is regulated by automatic reinforcement generated by wheel activity and an adjunctive pattern of running induced by the temporal presentation of sucrose. Furthermore, the findings question whether the sucrose contingency regulates wheel running as a reinforcing consequence.

Resurgence and repeated within-session progressive-interval thinning of alternative reinforcement.

Resurgence of a previously suppressed target behavior is common when reinforcement for a more recently reinforced alternative behavior is thinned. To better characterize such resurgence, these experiments examined repeated within-session alternative reinforcement thinning using a progressive-interval (PI) schedule with rats. In Experiment 1, a transition from a high rate of alternative reinforcement to a within-session PI schedule generated robust resurgence, but subsequent complete removal of alternative reinforcement produced no additional resurgence. Experiment 2 replicated these findings and showed similar effects with a fixed-interval (FI) schedule arranging similarly reduced session-wide rates of alternative reinforcement. Thus, the lack of additional resurgence following repeated exposure to the PI schedule was likely due to the low overall obtained rate of alternative reinforcement provided by the PI schedule, rather than to exposure to within-session reinforcement thinning per se. In both experiments, target responding increased at some point in the session during schedule thinning and continued across the rest of the session. Rats exposed to a PI schedule showed resurgence later in the session and after more cumulative alternative reinforcers than those exposed to an FI schedule. The results suggest the potential importance of further exploring how timing and change-detection mechanisms might be involved in resurgence.

The effects of warned loss magnitude and timeout duration on human avoidance behavior

This study experimentally investigated the determinants of avoidance behavior when participants are forewarned of aversive outcomes. The effects of 3 variables on avoidance behavior were examined: point-loss amount (5 levels, from 20 to 100 points), duration of timeout from positive reinforcement (5 levels, 20 to 100 s), and 3 predictive accuracy levels (100%, 50%, and 0%) of warning stimuli. Twelve participants completed 3 sessions, each comprising 25 discrete trials, that differed in predictive accuracy level. Throughout a session, a participant engaged in button press responses that were reinforced by points under a conjunctive fixed-ratio fixed-interval schedule. During each trial, a warning stimulus that indicated a loss amount and a timeout duration was presented. If the participant pressed the avoidance button, then the timeout started, otherwise the loss occurred. The trial ended with termination of timeout or an occurrence of the loss. Results showed that avoidance responses increased when the loss amount increased and decreased when the timeout duration increased. The frequency of avoidance responses was lowest when the predictive accuracy of warning stimuli was 0%. These findings demonstrated that this experimental procedure could be useful for investigating human avoidance behavior outside the laboratory.

Temporal contingencies are dependent on space location: Distal and proximal concurrent water schedules

Two studies evaluated the effect of delivering water depending on lever-pressing in a proximal or distant location to the water-producing response. Effects were measured on the spatial distribution of behavior and on the frequency and patterning of lever pressing. In both experiments water was available under two concurrent, complementary fixed interval schedules in two dispensers located at opposite ends of the chamber. The proportion of water deliveries in one dispenser relative to the second dispenser varied between phases, while the overall frequency was kept constant. In one study rats received water from a dispenser proximal to the water producing response location, whereas in the second study rats received water in the dispenser at the opposite panel where the response was emitted. The number of obtained water deliveries varied according to the programmed proportion, but rats obtained fewer deliveries under the distal location contingency. No systematic variations on space allocation were observed in neither experiment. The results are discussed in terms of the importance of considering the continuous interaction of time and space parameters in the analysis of behavior.

Use of technology in facilitating remote caregiver training for token systems

The prevalence of autism continues to rise, yet the ability to receive treatment or caregiver training through traditional in-person methods continues to be a precluding factor for many families. Studies have shown that parent training provides benefits to caregivers and children through increased success of interventions, implementation, and generalization of skills. This study evaluated the effect of using technology for remote caregiver training of a token economy for use during routine non-preferred activities. A multiple-baseline design was implemented across two participants, through three phases. Additional surveys and interviews were conducted to evaluate social validity. Results revealed that caregivers acquired necessary skills to implement the fixed interval schedule of reinforcement with token system and participants reported experiencing greater positive interactions with the children. Limitations of this study included no data were collected on the children’s behavior, nor were they trained on token economy use. Extraneous variables may have affected the results, such as unplanned household events. Results suggest that remote caregiver training can increase desirable interactions between caregiver and child, improve socially significant behaviors, and extend resources not typically available to all families.

Internal-Clock Models and Misguided Views of Mechanistic Explanations: A Reply to Eckard & Lattal (2020)

Eckard and Lattal's Perspectives on Behavior Science, 43(1), 5-19 (2020) critique of internal clock (IC) mechanisms is based on narrow concepts of clocks, of their internality, of their mechanistic nature, and of scientific explanations in general. This reply broadens these concepts to characterize all timekeeping objects-physical and otherwise-as clocks, all intrinsic properties of such objects as internal to them, and all simulatable explanations of such properties as mechanisms. Eckard and Lattal's critique reflects a restrictive billiard-ball view of causation, in which environmental manipulations and behavioral effects are connected by a single chain of contiguous events. In contrast, this reply offers a more inclusive stochastic view of causation, in which environmental manipulations are probabilistically connected to behavioral effects. From either view of causation, computational ICs are hypothetical and unobservable, but their heuristic value and parsimony can only be appreciated from a stochastic view of causation. Billiard-ball and stochastic views have contrasting implications for potential explanations of interval timing. As illustrated by accounts of the variability in start times in fixed-interval schedules of reinforcement, of the two views of causality examined, only the stochastic account supports falsifiable predictions beyond simple replications. It is thus not surprising that the experimental analysis of behavior has progressively adopted a stochastic view of causation, and that it has reaped its benefits. This reply invites experimental behavior analysts to continue on that trajectory.

Sustaining temporal attention prevents habit expression during operant learning in rats

As repeated operant performance promotes the transition from goal-directed action to habitual response, it appears that action-outcome contingency learning precedes and is necessary for the transition. Meanwhile, it is known that operant performance under a fixed interval (FI) schedule, in which the timing of reinforcement is predictable, is resistant to habit. However, the reason why the FI schedule prevents habit expression remains unclear. We reasoned that sustained attention for monitoring a certain interval might require a goal-directed process and prevent the transition. To verify this hypothesis, rats underwent FI schedule operant training while auditory cues were provided in a manner either contingent or non-contingent with the timing of lever pressing to obtain a reward. The subjects developed a habit with contingent cues, but not with either non-contingent cues or no cues. Overall, we conclude that the release from sustained attentional burden allows the expression of habit. (147 words)