Biasing the pacemaker in the behavioral theory of timing

In the behavioral theory of timing, pacemaker rate is determined by overall rate of reinforcement. A two-alternative free-operant psychophysical procedure was employed to investigate whether pacemaker period was also sensitive to the differential rate of reinforcement. Responding on a left key during the first 25 s and on a right key during the second 25 s of a 50-s trial was reinforced at variable intervals, and variable-interval schedule values during the two halves of the trials were varied systematically. Responding on the right key during the first 25 s and on the left key during the second 25 s was not reinforced. Estimates of pacemaker period were derived from fits of a function predicted by the behavioral theory of timing to right-key response proportions in consecutive 5-s bins of the 50-s trial. Estimates of pacemaker period were shortest when the differential reinforcer rate most strongly favored right-key responses, and were longest when the differential reinforcer rate most strongly favored left-key responses. The results were consistent with the conclusion that pacemaker rate is influenced by relative reinforcer rate.     

The mechanics of reinforcement

Mathematical principles of reinforcement were developed in order to (1) account for the interaction of target responding and other behavior; (2) provide a simple graphical representation; (3) deal with measurement artifacts; and (4) permit a coherent transition from a statics to a dynamics of behavior. Rats and pigeons were trained to make a target response while general activity was measured with a stabilimeter. The course of behavioral change was represented as a trajectory through a two-dimensional behavior space. The trajectories rotated toward or away from the target dimension as the coupling between the target response and the incentive was varied. Higher rates of reinforcement expanded the trajectories; satiation and extinction contracted them. Concavity in some trajectories provided data for a dynamic generalization of the model.     

Beyond inference by eye: Statistical and graphing practices in JEAB, 1992‐2017

Debates about the utility of p values and correct ways to analyze data have inspired new guidelines on statistical inference by the American Psychological Association (APA) and changes in the way results are reported in other scientific journals, but their impact on the Journal of the Experimental Analysis of Behavior (JEAB) has not previously been evaluated. A content analysis of empirical articles published in JEAB between 1992 and 2017 investigated whether statistical and graphing practices changed during that time period. The likelihood that a JEAB article reported a null hypothesis significance test, included a confidence interval, or depicted at least one figure with error bars has increased over time. Features of graphs in JEAB, including the proportion depicting single‐subject data, have not changed systematically during the same period. Statistics and graphing trends in JEAB largely paralleled those in mainstream psychology journals, but there was no evidence that changes to APA style had any direct impact on JEAB. In the future, the onus will continue to be on authors, reviewers and editors to ensure that statistical and graphing practices in JEAB continue to evolve without interfering with characteristics that set the journal apart from other scientific journals.     

The effect of research method type on stereotypes’ content: A brief research report

Stereotype Content Model (SCM) emphasizes the content rather than the underlying processes of the stereotypes and the content might be influenced by several cultural dimensions (e.g., individualism vs. collectivism). The main dimensions of SCM—namely warmth and competence—underlying various contents are assumed to be universal. However, from a cognitive science paradigm, we argue that different research methods (i.e., data collections and data analysis) might also yield different stereotype contents that might impact the universality versus specificity problem in the SCM. Indeed, using a sample from a collectivistic country (i.e., Romania), we found that using different methods in data collection (i.e., unstructured vs. semi-structured vs. structured interview) and different methods of data analysis (i.e., availability vs. accessibility scores) might be an important research strategy to counter artefacts and confusions in the universality versus specificity problem related to the SCM. Theoretical and practical implications are discussed.     

Understanding adherence to physiotherapy: Findings from an experimental simulation and an observational clinical study

This article reports two studies assessing the influence of self-efficacy, outcome expectancies and aversive feedback on different aspects of adherence. Study 1 employed a computer simulation of physiotherapy to test experimentally the effects of aversive feedback (i.e., loud noise) experienced during simulated therapy on adherence behaviour in a student population. Study 2 examined whether similar effects of aversive feedback (i.e., pain) experienced during physiotherapy in a clinical setting would be observed in a longitudinal questionnaire study of predictors of adherence. In both studies, self-efficacy and outcome expectancies were assessed at baseline and after experience of the task (performing simulated or actual physiotherapy). Study 1 found that self-efficacy and outcome expectancies predicted persistence with simulated physiotherapy (i.e., completing the experimental session), whereas aversive feedback influenced adherence during sessions (i.e., correct response rate). Study 2 found that self-efficacy and outcome expectancies predicted persistence with actual physiotherapy (i.e., completing the prescribed number of sessions). Aversive feedback and outcome expectancies influenced adherence during sessions. We conclude that different factors predict different aspects of adherence behaviour. It is therefore important to measure both persistence over time and adherence during sessions, and to investigate the predictors of each dimension of adherence.     

Human variable ratio performance

The generality of the mathematical principles of reinforcement (MPR) was tested with humans. In Experiment 1A, participants’ mouse clicks were reinforced according to a series of variable-ratio (VR) values. In one condition, a situated task was used (searching for treasure on a map presented via a PC monitor); in the other, abstract version of the task, participants clicked on a white screen. Under the “map” condition, response rates increased with increasing ratio value before decreasing with further ratio increases; under the “no-map” condition, response rates decreased linearly from a peak at the smallest ratio. In Experiment 1B, the pattern of responding was confirmed under the “map” conditions using a different set of ratio values. In Experiment 2, reinforcer magnitude was manipulated using the “map” context. Response rates did not differ significantly when large rather than small cash reinforcers were delivered according to a VR 30 but were significantly higher when large rather than small cash reinforcers were delivered according to a VR 120. Together these experiments offer qualified support for extending MPR to the behavior of human participants.     

Reinforcer quality matters: A test of the Mathematical Principles of Reinforcement with domestic hens (Gallus gallus domesticus)

This study evaluated the ability of Killeen's (1994) Mathematical Principles of Reinforcement to account for the effects of changes in reinforcer quality on hens' rates of responding on fixed‐ratio schedules. Hens were trained to peck a key on a fixed‐ratio schedule of reinforcement and then experienced an ascending series of ratio values in two separate conditions. In different conditions, the food reinforcer was either wheat or puffed wheat. Response rates initially increased with increases in ratio requirement before eventually decreasing at larger ratios. Quantitative fits of the model accounted for the data well. The fits revealed that different foods were systematically associated with changes in the specific activation parameter, a, and these were consistent with previous reports of preference for those food items.     

The effects of reinforcer magnitude in the preceding and upcoming ratios on between‐ratio pausing in multiple,mixed, and single fixed‐ratio schedules

Hens responded under multiple fixed‐ratio schedules with equal response requirements and either a 1‐s or a 6‐s reinforcer. Upcoming reinforcer size was indicated by key color. Components were presented in a quasirandom series so that all four component transitions occurred. Postreinforcement pauses were affected by the upcoming and preceding reinforcer size, with longer pauses after large reinforcers followed by small reinforcers than when followed by large ones, and longer pauses after small reinforcers that were followed by small reinforcers rather than large ones. Pauses increased with fixed‐ratio size and the effects of reinforcer size were larger the larger the ratio. When reinforcer size was not signaled—mixed fixed‐ratio schedules—pauses were shorter after small than after large reinforcers. Signalling the upcoming reinforcer attenuated the effect of the previous reinforcer size on pause duration when small was followed by small and when either small or large by large, but enhanced the effect when large was followed by small. There was no effect of reinforcer size on pause duration when single fixed‐ratio schedules were arranged. The effects of reinforcer size on pauses depends on the size and range of the fixed ratios as well as the exact procedures used in the study.     

Reinforced Behavioral Variability in Humans

The Psychological Record - This study aimed to assess the role of reinforced behavioral variability in the learning of a 6-digit target sequence (211212) with 3 groups of human participants (n =...     

The behavioral theory of timing: Reinforcer rate determines pacemaker rate

In the behavioral theory of timing, pulses from a hypothetical Poisson pacemaker produce transitions between states that are correlated with adjunctive behavior. The adjunctive behavior serves as a discriminative stimulus for temporal discriminations. The present experiments tested the assumption that the average interpulse time of the pacemaker is proportional to interreinforcer interval. Responses on a left key were reinforced at variable intervals for the first 25 s since the beginning of a 50-s trial, and right-key responses were reinforced at variable intervals during the second 25 s. Psychometric functions relating proportion of right-key responses to time since trial onset, in 5-s intervals across the 50-s trial, were sigmoidal in form. Average interpulse times derived by fitting quantitative predictions from the behavioral theory of timing to obtained psychometric functions decreased when the interreinforcer interval was decreased and increased when the interreinforcer interval was increased, as predicted by the theory. In a second experiment, average interpulse times estimated from trials without reinforcement followed global changes in interreinforcer interval, as predicted by the theory. Changes in temporal discrimination as a function of interreinforcer interval were therefore not influenced by the discrimination of reinforcer occurrence. The present data support the assumption of the behavioral theory of timing that interpulse time is determined by interreinforcer interval.