Journal of the experimental analysis of behavior最新文献

Simple discrimination reversal procedures have been successful in demonstrating functional equivalence classes in animals. The current study tested whether class expansion could be demonstrated in rats following the formation of functional equivalence classes. Olfactory stimuli were assigned to two arbitrary sets, and rats were trained on a successive simple discrimination task to respond to members of only one set at a time. When discriminated responding emerged, the reinforcement contingencies were reversed. After repeated reversals, probe sessions demonstrated functional equivalence classes in 14 of 15 rats across three experiments. Subsequently, the reversal procedure was used to train functional equivalence between one exemplar from each established class and two novel stimuli. Tests for class expansion, conducted between stimuli in the same set but without a history of training in the same session, were mixed. Experiment 1, which began expansion training after six-member classes were formed, did not provide clear evidence for class expansion. In Experiments 2 and 3, where expansion training began with smaller classes, class expansion was observed in six of eight rats. Class expansion is a property shared with human equivalence classes, suggesting that the discrimination reversal procedure provides a promising strategy for continuing research on equivalence in animals.

Two recent studies provided participants with their preferred music on synchronous schedules for increasing and decreasing their walking speed on a treadmill. Both studies demonstrated schedule control with most of their participants; however, the researchers speculated that presession rules may have contributed to this control. The purpose of this study was to examine how rules influenced schedule control of walking speed with the treadmill preparation. First, we randomly assigned 39 participants to one of three groups: accurate rules, inaccurate rules, or no rules. Second, we identified each participant's preferred music genre using a conjugate assessment. Third, we exposed each participant to five mixed-schedule components while they walked on a treadmill. The components differed in terms of the walking-speed requirements for participants to access reinforcement, and participants received accurate rules, inaccurate rules, or no rules about upcoming contingencies prior to each component presentation. Results showed schedule control emerged for (a) 8 of 13 (61%) participants in the accurate rules group, (b) 0 of 13 (0%) participants in the inaccurate rule group, and (c) 1 of 13 (7.69%) participants in the no rules group. Results also showed that 24 of 26 (92.3%) participants in the two rules groups changed their speed in accordance with the rules before contacting consequences. Collectively, the findings suggest that rules can either facilitate or impede schedule control with synchronous reinforcement schedules during the treadmill preparation.

Previous research has shown that divided-attention performance is sensitive to variations in relative reinforcement in a manner consistent with the generalized matching law. Two experiments with pigeons were designed to better understand the effects of different reinforcement conditions on divided-attention performance. Experiment 1 asked whether separate experience with different relative reinforcement probabilities for elements alone would produce changes in performance during nondifferentially reinforced divided-attention trials with compound samples consisting of those elements. The results suggest that accuracy following compound sample trials varied as a function of relative reinforcement experienced in element trials in a manner consistent with the matching law. Experiment 2 used an adjusting-sample-duration procedure to maintain constant accuracy on element and divided-attention trials and varied the probability of reinforcement across conditions. The sample durations that were required to maintain constant accuracy increased as reinforcement probability decreased even though that longer sample durations were required to maintain accuracy for compound-sample trials than for element-sample trials (the element-superiority effect). Overall, the present results are consistent with the notion that increased attention is allocated to stimuli that are associated with more reinforcement.

My collaboration with Peter Urcuioli started with research on delayed matching to sample. Initially we asked, what do pigeons remember during the delay in delayed matching to sample: a retrospective coding of the sample or a prospective coding of the comparison-related response? This led us to examine the basis of the differential outcomes effect. Why are samples associated with differential outcomes learned faster and remembered better than samples associated with common outcomes? This research helped us discover a procedure that resulted in functional stimulus equivalence: Samples associated with the same comparison are commonly associated. This research led Peter to develop his creative model of pigeon equivalence class formation. His model predicts the conditions under which pigeons satisfy the three components of what is known as Sidman equivalence: reflexivity, symmetry, and transitivity, phenomena that are difficult to demonstrate in pigeons. Importantly, his model predicts the opposite of reflexivity (anti-reflexivity) and symmetry (anti-symmetry). Research confirming Peter's model laid to rest the belief that the emergent relations defining Sidman equivalence can be satisfied only by an organism capable of using language. In his long career, Peter Urcuioli has made an important and long-lasting contribution to the field of learning and comparative cognition.

Dogs show numerousness, which is the ability to identify the larger of two stimuli, most often the number of treats on a plate. However, dogs seem to use mechanisms other than counting to make this discrimination. This study builds on existing research by controlling for (a) olfaction, (b) the surface area of the stimuli, and (c) delivery of a single reinforcer contingent on correct choices in the trained task. Nine dogs were trained to select a dish with 5 dots/treats in a sealed container when presented with comparison stimuli of 1, 4, and 9 dots/treats. The dogs showed numerousness in discriminating between dishes with 1 versus 5 dots, with consistent performance of more than 80% correct. Two dogs could discriminate 4 versus 5 dots, and three dogs learned the 9- versus 5-dot discrimination in which there is a conflict between selecting the larger option and selecting the 5 dots to gain reinforcement in the task. Knowledge of numerical competency, particularly training dogs to select the nonreinforced choice, can offer strategies to facilitate cognitive enrichment and learning in animals or offer enhancement of the capabilities of working dogs where the concept of number might be advantageous in providing additional skills.

A recent survey of the evidence on associative symmetry in humans revealed that nearly all the demonstrations either unintentionally trained backward stimulus pairings and/or had a temporal overlap between the stimuli being trained. We consider these criticisms and improve on our own method of “associative networks.” In this method, participants learn multiple stimulus pairings via arbitrary matching-to-sample tasks in which the stimuli are concurrently presented as sample and comparison stimuli. In Experiment 1, human participants learned a bidirectional network (in which symmetry was synergistic) and a unidirectional network (in which symmetry was antagonistic) or two unidirectional networks (removing explicit reinforcement of backward stimulus pairings). In Experiment 2, participants learned two unidirectional networks; however, we removed the temporal overlap between sample and comparison stimuli by imposing a 1-s delay between them. Both experiments showed robust evidence of symmetry, suggesting that the expression of symmetry in humans survives the most common confounds in published research.

In real-world settings, stimulus and outcome associations often depend on situational factors, such as Pavlovian occasion setters (OSs), which disambiguate whether a conditional stimulus (CS) will predict an outcome (unconditional stimulus; US). Whereas previous studies show that OSs are often lower in salience than CSs, no study has examined how low-salience OSs affect learning. In two conditioning experiments, we investigated this from the premise that inconsistently reinforced CSs prompt searching for additional stimuli (OSs) that indicate whether the CS will be followed by the US. Occasion setting learning was assessed using extinction rate—as partial reinforcement slows extinction relative to continuous reinforcement—and self-reported latent learning of stimuli. We hypothesized that a high-salience OS would result in faster extinction rates and occasion setting learning, whereas a low-salience OS would result in slower extinction rates and CS partial reinforcement learning. The results of Experiment 1 were mixed; there was no effect of OS salience on extinction rate, but the results for latent learning supported the hypothesis. We conducted Experiment 2 to specifically test extinction rate, and the results supported our hypothesis. The findings suggest that if a salient OS is found, occasion setting is learned; otherwise, CS partial reinforcement is learned.

This experiment was an investigation how reinforcers for one response in the presence of one stimulus may generalize to other dimensionally related stimuli. Four pigeons were trained on a three-alternative concurrent variable-interval schedule in which, after an initial condition, extinction was arranged for one alternative. In Part 1, we varied the reinforcer rate on a dimensionally distant alternative while keeping the reinforcer rate on the dimensionally closer stimulus constant. In Part 2, the reinforcer rate for the distant alternative was kept constant and that for the closer alternative was varied. Increasing the reinforcer rate for the closer alternative increased responding on the extinction alternative, but increasing the reinforcer rate on the distant alternative decreased extinction response rates. This result is predicted by the generalization across dimensions model. This model also helps to explain the results from previously reported choice research that involves multiple alternatives, and particularly why Luce's indifference principle is sometimes supported and sometimes not.

How the subjective value of an outcome changes as a function of time, probability, or effort has been an active area of psychological and economic research for decades. The exact functional form of how a commodity is discounted has been debated, and there have been numerous forms proposed. One of the challenges when trying to determine the functional form of discounting data is how models are compared, what modeling methods are used, how many data points are used, and what comparison metrics were used. Thus, we sought to replicate and extend previous research comparing discounting model selection methods by simulating discounting data from five functional forms: the Mazur hyperbolic model (Mazur, 1987), Rachlin hyperboloid (Rachlin, 2006), Myerson–Green hyperboloid (Myerson & Green, 1995), Samuelson exponential model (Samuelson, 1937), and beta-delta model (Laibson, 1997). With each of these models we manipulated the number (i.e., density) of data points, used two forms of modeling, and assessed the degree to which each model generalizes to data it has not used in the fitting process. Model comparisons were conducted using the Akaike information criterion (AIC), Bayesian information criterion (BIC), and leave-one-out cross validation (LOOCV). In general, AIC, BIC, and LOOCV selected the correct model, whereas the Rachlin model had the lowest error across folds of LOOCV when relying on multilevel modeling.

Resurgence refers to the recurrence of a previously reduced or eliminated operant following the worsening of reinforcement conditions for an alternative behavior. The contextual account of resurgence posits that the discriminative properties of reinforcers modulate this relapse. Evidence supporting the contextual account of resurgence stems from translational laboratory investigations with nonhuman subjects. The purpose of the current study was to further translate this work using a human-operant preparation with a young boy with autism and intellectual disability across three experiments. Experiment 1 was conducted according to a conventional three-phase resurgence preparation. In Experiment 2, the reinforcer (O2) that maintained the alternative response (R2) in Phase 2 was delivered noncontingently in Phase 3. Finally, in Experiment 3 the reinforcer (O1) that maintained the target response (R1) in Phase 1 was delivered noncontingently in Phase 3. Although both O1 and O2 mitigated resurgence relative to extinction alone, the magnitude of resurgence was slightly higher with O2  deliveries. Our results are generally consistent with the contextual account of resurgence. The influence of a differential-reinforcement-of-other-behavior contingency in Phase 3 and other procedural aspects of this study are discussed, as are applied implications for reducing relapse in behavioral treatments.