Concurrent Chains Research Articles

Effects of methamphetamine on probability discounting in rats using concurrent chains

How stimulant drugs affect risky choice and the role of reinforcement magnitude has been an important question for research on impulsivity. This study investigated rats’ responding on a rapid acquisition, concurrent chains, probability discounting task under methamphetamine administration. In each block of four sessions, probability of reinforcement delivery was unequal (0.5/1.0, 1.0/0.5) or equal, (1.0/1.0, 0.5/0.5) while amount of reinforcement was constant and unequal. This allowed for an estimate of probability discounting and the magnitude effect (where larger reinforcers are discounted at a greater rate) in each block. Baseline, acute and chronic methamphetamine administration, and re-establish baseline phases were completed. Rats showed sensitivity to probability and magnitude in baseline, as well as a magnitude effect whereby preference for the larger reinforcement was greater with 100% than 50% reinforcement probability. Acute methamphetamine dose-dependently reduced the probability effect. There were no effects of chronic administration and only probability discounting was maintained in the re-establish baseline phase. This was the first procedure to find a magnitude effect with rats in a probability discounting procedure and demonstrates that acute methamphetamine reduces both the probability and magnitude effects which increases propensity for risky choice.

An Evaluation of Ethnicity-Matching for Caregiver Telehealth Training in India.

Telehealth has become an increasingly viable service delivery option for function-based treatment of problem behavior (Lindgren et al., 2016). However, few applications have occurred with participants outside the United States and little research exists evaluating the role that culture plays in service delivery. In the current study, we compared functional analyses and functional communication training delivered via telehealth by ethnically matched and ethnically distinct trainers to six participants in India. We measured the effectiveness using a multiple baseline design while collecting supplemental measures of sessions to criterion, cancellations, treatment fidelity, and social validity. We directly assessed preference for the ethnically matched and ethnically distinct trainers using a concurrent chains arrangement. Sessions with both trainers were effective in reducing problem behavior and increasing functional verbal requests for participating children, and treatment fidelity was high across training modalities. There were no major differences in sessions-to-criterion or cancellations across trainers. However, all six caregivers demonstrated greater preference for sessions with the ethnically matched trainer.

Stimulus control depends on the subjective value of the outcome.

Stimuli that provide information about likely future reinforcers tend to shift behavior, provided a reliable relation between the stimulus and the reinforcer can be discriminated. Stimuli that are apparently more reliable exert greater control over behavior. We asked how the subjective value (measured in terms of preference) of reinforcers associated with stimuli influences stimulus control. Five pigeons worked on a concurrent chains procedure in which half of all trials ended in a smaller reinforcer sooner, and the other half in a larger reinforcer later. In Signaled trials, the color and flash duration on the keys in the initial link signaled the outcome of the trial. In Conflicting probe trials, the color and the flash duration signaled conflicting information about the outcome of the trial. Choice in Signaled trials shifted toward the signaled outcome, but was never exclusive. In Conflicting probe trials, control was divided idiosyncratically between the 2 stimulus dimensions, but still favored the outcome with the higher subjective value. Thus, stimulus control depends not only on the perceived reliability of stimuli, but also on the subjective value of the outcome.

Choice for reinforced behavioral variability in children with autism spectrum disorder.

Although individuals with autism spectrum disorder (ASD) tend to behave repetitively, certain reinforcement contingencies (e.g., lag schedules) can be used to increase behavioral variability. In a lag schedule, reinforcers only follow responses that differ from recent responses. The present study was designed to promote variable play behavior in preschoolers with ASD interacting with playsets and figurines and to assess preference for variability and repetition contingencies. Data have shown a preference for variability in pigeons and college students, but this effect has not been explored in clinical populations. In this experiment, preschoolers with ASD were taught to discriminate between variability and repetition contingencies. Only play behaviors that met a lag schedule were reinforced in the presence of one color, and only repetitive behaviors were reinforced in the presence of another. After differential performance was established, participants experienced a concurrent chains schedule. Participants chose between the colors taught in training and then completed a play session with the selected contingency. One participant selected variability and repetition equally. The other participants showed a slight preference for variability. These results indicate that some individuals with ASD may play repetitively, not because they prefer repetition, but because they require additional teaching to play variably.

A systematic evaluation of prompt fading methods during conditional discrimination training

ABSTRACT Prompt fading methods are widely used to teach conditional discriminations to learners with developmental disabilities. To date, very little research has investigated the relative effectiveness of the various prompt fading methods described in the literature. Furthermore, learner preference for these instructional tactics has rarely been evaluated. The present study compared the relative effectiveness of three prompt fading methods (most-to-least with an embedded constant time delay, least-to-most, and progressive time-delay) to a control condition. Three boys with autism participated in the study. Two met mastery during the prompt fading assessment (one in progressive time-delay, and one in least-to-most prompting). In a subsequent concurrent chains preference assessment, both participants indicated a preference for the fading method that had been most effective. Considerations for practitioners when selecting prompt fading methods as well as procedural parameters warranting further investigation are discussed.

Effects of schedule type and terminal‐link duration on choice in concurrent chains

Four pigeons responded in a three-component concurrent chains procedure in which the terminal-link schedules were either both fixed-interval (FI FI), both variable-interval (VI VI), both mixed-interval (MI MI) or variable-interval fixed-interval (VI FI). Across components within sessions, overall terminal-link duration was varied while schedule types were varied across conditions. For the conditions with homogeneous schedules, the strongest preference was obtained with FI FI, intermediate with MI MI, and weakest with VI VI. Preference increased with overall terminal-link duration for all schedules, but the increase was more rapid for VI FI. The hyperbolic value-added model (HVA) and cumulative decision model (CDM) were fitted to the choice data and accounted for 83.9% and 76.1% of the variance, respectively. However, deviations from both models' predictions were systematic. A modification of the CDM, which assumed that reinforcers delivered after variable delays were more effective, improved the fit of the model and substantially reduced the systematic deviations in residuals. Comparable modifications of HVA produced only limited improvement. Results show that preference in concurrent chains with homogeneous terminal links depends on the degree of variability in reinforcer delays, and that the CDM can provide an excellent account of results across different terminal-link schedules.

Exchange schedules in token economies: A preliminary investigation of second‐order schedule effects

Basic research shows that token‐production and exchange‐production schedules in token economies affect each other as second‐order schedules (i.e., the exchange‐production schedule's requirements affect responding toward the token‐production schedule). This relationship has not been investigated with children in academic settings despite the widespread use of token economies in this context. This study compared the effects of fixed‐ratio (FR) and variable‐ratio (VR) exchange‐production schedules of equal ratios (2, 5, and 10) on responding toward an FR 1 token‐production schedule with a child diagnosed with autism. A concurrent chains assessment was also conducted to assess the participant's relative preference for FR and VR exchange‐production schedule arrangements within her typical discrete trial training. Results showed no difference in response rate between the two schedule types. However, the concurrent chains assessment revealed an exclusive preference for the VR arrangement.

Using a Tablet Device to Examine Effects of Varied Reinforcement and Preference

The present study examined effects of providing varied reinforcement versus constant reinforcement using an iPad and applications (apps). Participants included three typically developing children in a school setting. We conducted a preference assessment to identify highly preferred and moderately preferred apps. We then conducted a concurrent chains assessment to examine responding for varied moderately preferred content or constant highly preferred content. Although participants demonstrated different response patterns, all participants responded to gain access to varied moderately preferred reinforcement more than constant highly preferred reinforcement although preference for content alone would not have predicted this outcome. This research has implications for using high-tech devices (i.e., iPads) as reinforcers in educational settings.

Preference, resistance to change, and the cumulative decision model.

According to behavioral momentum theory (Nevin & Grace, 2000a), preference in concurrent chains and resistance to change in multiple schedules are independent measures of a common construct representing reinforcement history. Here I review the original studies on preference and resistance to change in which reinforcement variables were manipulated parametrically, conducted by Nevin, Grace and colleagues between 1997 and 2002, as well as more recent research. The cumulative decision model proposed by Grace and colleagues for concurrent chains is shown to provide a good account of both preference and resistance to change, and is able to predict the increased sensitivity to reinforcer rate and magnitude observed with constant-duration components. Residuals from fits of the cumulative decision model to preference and resistance to change data were positively correlated, supporting the prediction of behavioral momentum theory. Although some questions remain, the learning process assumed by the cumulative decision model, in which outcomes are compared against a criterion that represents the average outcome value in the current context, may provide a plausible model for the acquisition of differential resistance to change.

Feasibility of and teacher preference for student-led implementation of the good behavior game in early elementary classrooms.

The Good Behavior Game (GBG) is a classwide group contingency shown to reduce disruptive student behavior. We examined the feasibility of training young students to lead the GBG in one first-grade and three kindergarten classes. We also examined teacher preference for teacher-led GBG, student-led GBG, or no GBG using a concurrent chains procedure. We successfully trained students in all classes to lead the GBG, and the GBG reduced disruptive behavior regardless of who implemented it. Preference for who implemented the game varied across teachers. Results of this study suggest that students as young as kindergarten age can be trained to implement the GBG and that teacher preference should be taken into account when determining how classwide interventions are to be implemented.

Procrastination in the pigeon: Can conditioned reinforcement increase the likelihood of human procrastination?

Procrastination is the tendency to put off initiation or completion of a task. Although people are typically known to procrastinate, recent research suggests that they sometimes "pre-crastinate" by initiating a task sooner than they need to (Rosenbaum et al. in Psychological Science, 25(7), 1487-1496, 2014). A similar finding of precrastination was reported by Wasserman and Brzykcy (Psychonomic Bulletin & Review, 22, 1130-1134, 2015) with pigeons using a somewhat different procedure. In the present experiment, we used a procedure with pigeons that was more similar to the procedure used by Rosenbaum et al. Pigeons were given a choice between two sequences of events (concurrent chains). Choice of the procrastination chain resulted in color A, which 15-s later would change to color B and 5-s later resulted in reinforcement. Choice of the precrastination chain resulted in color C, which 5-s later would change to color D and 15-s later resulted in reinforcement. Thus, both chains led to reinforcement after 20 s. Results indicated that the pigeons procrastinated. That is, they preferred the 15-5 chain over the 5-15 chain. The results are consistent with Fantino's (Journal of the Experimental Analysis of Behavior, 12, 723-730, 1969) delay reduction theory, which posits that stimuli that signal a reduction in the delay to reinforcement, such as the 5-s stimulus that occurred immediately prior to reinforcement, serve as strong conditioned reinforcers and should be preferred. In support of this theory, the pigeons pecked most at the 5-s stimulus that led immediately to reinforcement, indicating that it had become a strong conditioned reinforcer. The results suggest that delay reduction theory, a theory that emphasizes the attraction to stimuli that predict reinforcement with a short delay, also may contribute to human procrastination behavior because when task completion comes just before the deadline, it may become a stronger conditioned reinforcer than if task completion comes earlier.

Multiobjective bi-level programming for shared inventory with emergency and backorders

The goal of this study is to model a shared inventory model as a bilevel programming problem. The model considers both emergency and backorders so decision makers have flexibility in meeting customer needs and extends the satisfaction level is higher than the simple model with no emergency and backorders. We focus on the interaction between decision makers in an uncertain environment. The considered situation consists in a large corporation that owns a warehouse and two concurrent chains. The company opted for shared inventory policy. The corporation is looking into minimizing its inventory and reducing the overtime for its personnel. The chains, independently, are trying to minimize their inventory costs. The chains are allowed to submit emergency and backorders to minimize their inventory cost while increasing their customers’ satisfaction. The warehouse plays the role of a leader and optimizes its objectives first then the two chains, as followers, try to satisfy their objectives independently. The problem is formulated into a decentralized bilevel programming problem where the leader has multiple objectives. We formulate the situation as a biobjective bilevel the mathematical program and we propose ways to solve it. . Our simulation, inspired from a real case, shows a cost reduction of up to 8.9 % compared to regular use of inventory model.

A cumulative decision model for three-alternative choice in concurrent chains.

Traditional models for choice in the concurrent-chains procedure have assumed that terminal-link stimuli acquire value as conditioned reinforcers, and that 2-alternative choice provides a measure of relative value according to the matching law. By contrast, the cumulative decision model (CDM; Christensen & Grace, 2010) explains choice as the aggregate effect of comparing delays to a criterion on initial-link responding, not conditioned reinforcement. Here we test whether the CDM can account for choice in 3-alternative concurrent-chains (3ACC) and compare it with the hyperbolic value-added model (HVA; Mazur, 2001), which assumes that choice depends on the increase in conditioned reinforcement value signaled by terminal-link stimuli and has been successful in previous 3ACC research (Mazur, 2000). In Experiment 1, 4 pigeons responded in 3ACC in which the terminal links were fixed-interval schedules, and parameter estimates from fits of CDM and HVA were used to calculate predictions for conditions with variable-interval terminal links. The predictions of CDM were more accurate than those of HVA. In Experiment 2, 7 pigeons responded in 3ACC in which the terminal links were fixed-interval schedules. Although both models described the data well, residuals from HVA fits showed a systematic pattern predicted by CDM, characterized by a third-order polynomial with a negative cubic coefficient. Finally, we conducted a residual meta-analysis (Sutton, Grace, McLean, & Baum, 2008) of data from prior 3ACC studies. HVA residuals showed the same negative cubic pattern as in Experiment 2, whereas no systematic pattern was found in the CDM residuals. Overall, results support the CDM and suggest that the same principles which describe binary choice in concurrent chains generalize without modification to 3-alternative choice. (PsycINFO Database Record

Accelerated Dimension-Independent Adaptive Metropolis

This work describes improvements by algorithmic and architectural means to black-box Bayesian inference over high-dimensional parameter spaces. The well-known adaptive Metropolis (AM) algorithm [H. Haario, E. Saksman, and J. Tamminen, Bernoulli, (2001), pp. 223--242] is extended herein to scale asymptotically uniformly with respect to the underlying parameter dimension for Gaussian targets, by respecting the variance of the target. The resulting algorithm, referred to as the dimension-independent adaptive Metropolis (DIAM) algorithm, also shows improved performance with respect to adaptive Metropolis on non-Gaussian targets. This algorithm is further improved, and the possibility of probing high-dimensional (with dimension $d \geq 1000$) targets is enabled, via GPU-accelerated numerical libraries and periodically synchronized concurrent chains (justified a posteriori). Asymptotically in dimension, this GPU implementation exhibits a factor of four improvement versus a competitive CPU-based Intel MKL (math kernel library) parallel version alone. Strong scaling to concurrent chains is exhibited, through a combination of longer time per sample batch (weak scaling) with fewer necessary samples to convergence. The algorithm performance is illustrated on several Gaussian and non-Gaussian target examples, in which the dimension may be in excess of one thousand.

Basic Properties of Coherence: Testing a Core Assumption of Relational Frame Theory

Relational frame theory contains a foundational assumption that coherence (i.e., making sense) is reinforcing for verbally competent humans. That is, it is assumed that humans relate ambiguous stimuli together because they have an extensive learning history where doing so resulted in both effective environmental action and socially mediated reinforcement (e.g., praise, positive attention). This investigation tested this core assumption of relational frame theory by analyzing response patterns to ambiguous stimuli in a matching-to-sample task (Study 1) and by assessing whether participants displayed a preference toward coherent contexts in a concurrent chains preparation (Study 2). The majority of participants responded to ambiguous stimuli in ways that were internally consistent and congruent with their previous learning histories in the absence of any programmed contingencies. Many participants also displayed a preference toward contexts where coherent responding was possible, and there was a trend toward switching away in preference when it became increasingly costly to access the coherent context. The major theoretical contributions of these findings are discussed.

ASSESSMENT OF THERAPISTS' PREFERENCES FOR DISCONTINUOUS MEASUREMENT SYSTEMS

Recent studies have evaluated the sensitivity of discontinuous recording methods for detecting behavior changes; however, relatively few have evaluated observers' preferences for such methods. To address this limitation, this study used a concurrent chains design to evaluate eight therapists' preferences for collecting data using momentary time sampling (MTS) and partial interval recording with interval sizes of 10 s and 1 min. Results of the preference assessment showed that six of the eight therapists preferred to collect data using 1‐min MTS; however, results of a follow‐up questionnaire suggest that most therapists preferred 1‐min MTS primarily because it was easy to use rather than that it was accurate. These results are discussed with respect to recent findings on the sensitivity of MTS and partial interval recording. Copyright © 2014 John Wiley & Sons, Ltd.

Quantifying transitions in response allocation with change point analysis in concurrent chains

Research based on the matching law has demonstrated empirically that the physical and temporal properties of the events, the context in which they occur and the signals that mark them in space and time all contribute to response allocation. When the physical or temporal properties of different outcomes change in ways that affect their relative value, the ratio of responses to each outcome adjusts with time and exposure to the new contingency. Five pigeons pecked in concurrent-chain schedules with fixed-interval terminal links. Terminal-link schedules were changed each session. In most sessions, response allocation was initially indifferent to terminal-link schedules but shifted to favor the initial link associated with the shorter terminal link. As a first step to disambiguating response allocation in transition from stable response allocation, transition durations were interpolated from change points in cumulative response plots. The relation between transition duration and absolute log immediacy ratio was negative: the number of initial links until the shift occurred was longer when terminal-link schedules were relatively similar than when they were relatively different.

Choices between segmented and unsegmented schedules and the self-control paradigm

A concurrent-chains procedure was used to examine choice between a segmented (two- or three-terminal-link segments schedules) and an unsegmented schedule (simple schedule) in terminal links with equal interreinforcement intervals. In most such experiments, preference for the unsegmented schedule has been found, but in a recent study with humans (Alessandri et al., 2010) a reversal in preference was found when, in the segmented schedule, the terminal link segmenting stimulus was presented briefly and closer to food delivery such that the early terminal link stimulus was temporally closer to the food delivery. In Experiment 1, an attempt to replicate this latter effect with pigeons was unsuccessful but this outcome was consistent with an account in terms of a self-control contingency involving conditioned reinforcers. According to this account, the unsegmented alternative consisted of an immediate, smaller presentation of a conditioned reinforcer (i.e., the impulsive, and thus usually the preferred, option in several experiments) and the segmented schedule led to a delayed, larger conditioned reinforcer (i.e., the self-control option). In Experiment 2, a reversal of preference toward the segmented schedule was found when a delay was added to both terminal links between the reinforced initial-link response and the onset of the corresponding terminal link stimulus. This result is consistent with a similar effect found with primary reinforcers in the self-control literature suggesting the utility of self-control as an account of preferences for unsegmented terminal links of concurrent chains schedules.

Decentralised bilevel model for shared inventory management

In this study, we consider the case of a large corporation that owns a warehouse and two concurrent chains. The company opted for shared inventory policy. The warehouse is looking into minimising its inventory cost and at the same time reducing the fluctuation of the personnel. The chains, independently, are trying to minimise their inventory costs. The warehouse plays the role of a leader in optimising its objectives and, as followers, the two chains try to satisfy their objectives. The problem is formulated into a decentralised nonlinear bilevel programming problem. We also consider the fuzziness of some parameters due to the imprecise available information. We propose the mathematical model and we solve it for our specific case.

Comment on Gallistel

In this article, Gallistel proposes information theory as an approach to some enduring problems in the study of operant and classical conditioning.