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Knee osteoarthritis is among the most prevalent chronic diseases. Total knee arthroplasty is a common solution that effectively addresses the continued structural degeneration of the articular cartilage. However, effective physical therapy is critical for recovery. Despite participating in physical therapy, many patients fail to recover. This study investigated the potential efficacy of a behaviorally informed approach to surface electromyographic biofeedback following total knee arthroplasty relative to the clinical standard, neuromuscular electrical stimulation. The surface electromyographic biofeedback procedure incorporated improved techniques for establishing a baseline and individualized and adjusting criteria for feedback. The findings suggest some advantages for surface electromyographic biofeedback over neuromuscular electrical stimulation in quadriceps strength, range of motion, functional recovery, and quality of life. Behaviorally informed surface electromyographic biofeedback holds promise for total knee arthroplasty recovery and these data suggest considerable room for collaboration between behavior analysts and physical therapists.

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Sidman's (2000) theory of stimulus equivalence states that all positive elements in a reinforcement contingency enter an equivalence class. The theory also states that if an element from an equivalence class conflicts with a reinforcement contingency, the conflicting element will "drop out" of the class. Minster et al. (2006) found evidence that a conflicting reinforcer does not drop out of an equivalence class. To explain their results, they proposed that the reinforcer enters the class via pairing after conditional relations have been established, and when there is a conflict between the class and the contingencies, conditionally related elements that have a longer history in the class and that were brought in via reinforcement will exert stronger control. In the current study, stimulus-reinforcer relations were established before conditional relations to assess the role of developmental order of stimulus relations on conditional-discrimination performance. The results replicate the findings of Minster et al. (2006) but suggest that developmental order may not be an important factor contributing to maintained accuracy on baseline conditional relations. An interpretation of "dropping out" in terms of differentiated subclasses is discussed. The relevance of the results to the phenomenon known as the differential outcomes effect is also discussed.

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Many problems that fall in medical domains of inquiry have behavioral components that can be optimized to increase benefits for patients. For example, although surgical intervention is effective in reducing the pain resulting from osteoarthritis of the knee, patients often struggle to regain complete functional use of the joint. In this translational study, we point to some ways in which behavioral contingencies of reinforcement are compromised, making the recovery process more difficult. We also report on the use of surface electromyography (sEMG) with healthy participants to create supplementary contingencies of reinforcement to support the development and maintenance of clinically relevant exercises. The procedures reported provide a proof-of-concept and can contribute to an increase in the systematic use of games and feedback in physical rehabilitation in recovery from knee surgery. The results of this translational study suggest an expanded role for applied behavior analysis in the domains of health and medicine.

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The study presented here investigated the effect of common and uncommon elements on class merger as predicted by Sidman in his reconceptualization of stimulus equivalence suggesting that common elements among contingencies can facilitate emergent performances (1994, 1997, 2000). Eight adult participants were exposed to a procedure that arranged for stimulus-reinforcer correlations in Phase 1 and response-reinforcer correlations in Phase 2 of a 3-phase study. In the common element group, the visual images serving as reinforcers were the same in Phase 1 and Phase 2. In the uncommon elements group, the images serving as reinforcers were different in Phases 1 and 2. In Phase 3, participants were given an opportunity to respond but no feedback was programmed. The results showed that participants' responding was well differentiated in the common element group and undifferentiated in the uncommon elements group. These results are predicted by Sidman's revised formulation of the provenance and scope of equivalence relations. Specifically, these data support Sidman's (1994, 1997, 2000) suggestion that elements of a contingency enter into an equivalence class and common elements among contingencies are sufficient to produce class mergers. The findings highlight an emergent simple discrimination and raise some interesting considerations about the definition of equivalence under the new formulation.

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The establishment of sample/S- relations (or reject control) during conditional discrimination training (AB, BC) affects transitivity (AC), equivalence (CA) and reflexivity (AA, BB, CC) test outcomes. The present study parametrically evaluated the effects of different observing patterns to comparison stimuli on the establishment of reject control during baseline conditional relation training. A matching-to-sample with observing requirements (MTS-OR) procedure was implemented during AB and BC conditional discrimination training. During training, the participants were required to observe the sample and incorrect comparison on every trial before responding. In addition, the participants were divided into three groups that differed regarding the percentage of training trials on which they were prevented from observing the correct comparison stimuli: 25%, 50%, and 75%. Once the mastery criteria were achieved during training, transitivity (AC), symmetry (BA, CB), equivalence (CA), and reflexivity (AA, BB, CC) tests were conducted with all comparison stimuli visible from the beginning. The results suggest that the number of errors during transitivity, equivalence, and reflexivity tests progressively increased as participants were prevented from observing the correct comparison on a greater number of trials during training. Symmetry test results, however, were not affected by the experimental manipulation. Moreover, the number of participants showing reject-control patterns during tests slightly increased and the number of participants showing select-control patterns decreased as a function of the number of trials on which the participants were prevented from observing the correct comparison. Thus, we suggest that observing patterns during training is a relevant variable that affects equivalence test outcomes.

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In the current study we assessed the possibility of developing intraexperimentally behavioral priming and Event Related Potentials (ERP) effects that are often studied with stimuli to which participants typically have a very extensive pre-experimental history, like words. To do so we used abstract geometrical figures in a baseline Lexical Decision Task (LDT), followed by a conditional discrimination-training phase. We then repeated the LDT task to assess the effectiveness of training compared to baseline. We found that participants' reaction time data in the post training LDT session changed, compared to the pre-training LDT session, according to the specific conditional discriminations taught in the training session. Similarly, neural results suggest the presence of an effect due to training that is absent in the baseline neural measures. Moreover, similar effects were also obtained using words. Results point to the possibility that conditional discrimination learning may be sufficient to establish effects that are often considered to be language specific.

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We describe here two approaches introduced by Abrahamsen (1987) that can be used by behavior analysts to interpret neuroscientific data. The first is a "boundary-bridging" approach aimed at understanding the interdisciplinary interactions between the behavioral and the neural levels of analysis while keeping the two domains independent. When presenting the boundary-bridging approach, we describe neuroplasticity, a perspective that describes how changes at the brain level can be understood by examining behavioral factors. In the second part of the paper, we contrast two "boundary-breaking" perspectives: neuropsychology and behavior analytic neuroscience. In neuropsychology, localized brain activation is used to explain behavior. In behavior analytic neuroscience, brain responses are interpreted as behavior. We discuss the conditions under which brain responses can be considered behavior and propose that including brain responses within a behavioral framework may allow carrying out a more sophisticated and temporally detailed behavior analysis.

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The present study used a single-subject design to evaluate the effects of select or reject control on equivalence class formation and transfer of function. Adults were exposed to a matching-to-sample task with observing requirements (MTS-OR) in order to bias the establishment of sample/S+ (select) or sample/S- (reject) relations. In Experiment 1, four sets of baseline conditional relations were taught-two under reject control (A1B2C1, A2B1C2) and two under select control (D1E1F1, D2E2F2). Participants were tested for transitivity, symmetry, equivalence and reflexivity. They also learned a simple discrimination involving one of the stimuli from the equivalence classes and were tested for the transfer of the discriminative function. In general, participants performed with high accuracy on all equivalence-related probes as well as the transfer of function probes under select control. Under reject control, participants had high scores only on the symmetry test; transfer of function was attributed to stimuli programmed as S-. In Experiment 2, the equivalence class under reject control was expanded to four members (A1B2C1D2; A2B1C2D1). Participants had high scores only on symmetry and on transitivity and equivalence tests involving two nodes. Transfer of function was extended to the programmed S- added to each class. Results from both experiments suggest that select and reject controls might differently affect the formation of equivalence classes and the transfer of stimulus functions.

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Psychologists interested in the study of symbolic behavior have found that people are faster at reporting that two words are related to one another than they are in reporting that two words are not related - an effect called semantic priming. This phenomenon has largely been documented in the context of natural languages using real words as stimuli. The current study asked whether laboratory-generated stimulus-stimulus relations established between arbitrary geometrical shapes would also show the semantic priming effect. Participants learned six conditional relations using a one-to-many training structure (A1-B1, A1-C1, A1-D1, A2-B2, A2-C2, A2-D2) and demonstrated, via accurate performance on tests of derived symmetry, that the trained stimulus functions had become reversible. In a lexical decision task, subjects also demonstrated a priming effect as they displayed faster reaction times to target stimuli when the prime and target came from the same trained or derived conditional relations, compared to the condition in which the prime and target came from different trained or derived conditional relations. These data suggest that laboratory-generated equivalence relations may serve as useful analogues of symbolic behavior. However, the fact that conditional relations training and symmetry alone were sufficient to produce the effect suggests that semantic priming like effects may be the byproduct of simpler stimulus-stimulus relations.

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The titrating-delay matching-to-sample (TDMTS) procedure offers researchers an additional behavioral task thought to capture some important features of remembering. In this procedure, the delay between sample offset and comparison onset adjusts as a function of the subject's performance. Specifically, correct matches increase the delay and incorrect matches decrease the delay, and steady-state titrated delays serve as the primary dependent measure. The present series of experiments investigated the effects of several procedural variables on performance in TDMTS procedures in an effort to elucidate better its features to allow for more precision in future use. Experiment 1 reports results from a parametric analysis of fixed-ratio response requirements on the sample key that indicated improved remembering in the form of higher daily titrated delay values as the requirement was increased. Experiment 2 investigated the extent to which the initial delay value in each session affected session-wide delay values. Results indicated that regardless of value of the initial delay, the subjects' performances adjusted the delay values in the direction of the known baseline delay-value levels. Experiment 3 manipulated the step size by which delay values were adjusted and the results indicated that larger step sizes increased both session-to-session variability and within-session range of titrated delay values, although the average values remained approximately the same. These results suggest that the TDMTS task serves as a promising procedure to study what many refer to as memory.

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Adult human subjects engaged in a simulated Rock/Paper/Scissors game against a computer opponent. The computer opponent's responses were determined by programmed probabilities that differed across 10 blocks of 100 trials each. Response allocation in Experiment 1 was well described by a modified version of the generalized matching equation, with undermatching observed in all subjects. To assess the effects of instructions on response allocation, accurate probability-related information on how the computer was programmed to respond was provided to subjects in Experiment 2. Five of 6 subjects played the counter response of the computer's dominant programmed response near-exclusively (e.g., subjects played paper almost exclusively if the probability of rock was high), resulting in minor overmatching, and higher reinforcement rates relative to Experiment 1. On the whole, the study shows that the generalized matching law provides a good description of complex human choice in a gaming context, and illustrates a promising set of laboratory methods and analytic techniques that capture important features of human choice outside the laboratory.

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The present report analyzes trends in attendance and presentations at the annual conference of the Association for Behavior Analysis (ABA). Numbers of registered attendees were plotted over time. The trends show that the number of registered attendees has grown considerably over the last three decades, with the largest proportion of the growth occurring during the last 10 years. This growth is shown to be correlated with the introduction of board certification in behavior analysis (BCBA and BCABA). In addition, conference programs from 1980 through 2007 were coded, and all presentations were categorized into one of four areas (application, basic research, conceptual, and verbal behavior) based on the primary designator codes chosen by the authors at the time of submission. An analysis of the total number of presentations in each category indicates that applied research presentations have always outnumbered the other three categories. The absolute number of presentations related to application has grown faster than presentations in other categories. However, correcting for population growth shows that the relative proportion of presentations in the four areas has remained fairly constant over the last 28 years.

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Four pigeons were exposed to a token-based self-control procedure with stimulus lights serving as token reinforcers. Smaller-reinforcer choices produced one token immediately; larger-reinforcer choices produced three tokens following a delay. Each token could be exchanged for 2-s access to food during a signaled exchange period each trial. The main variables of interest were the exchange delays (delays from the choice to the exchange stimulus) and the food delays (also timed from the choice), which were varied separately and together across blocks of sessions. When exchange delays and food delays were shorter following smaller-reinforcer choices, strong preference for the smaller reinforcer was observed. When exchange delays and food delays were equal for both options, strong preference for the larger reinforcer was observed. When food delays were equal for both options but exchange delays were shorter for smaller-reinforcer choices, preference for the larger reinforcer generally was less extreme than under conditions in which both exchange and food delays were equal. When exchange delays were equal for both options but food delays were shorter for smaller-reinforcer choices, preference for the smaller reinforcer generally was less extreme than under conditions in which both exchange and food delays favored smaller-reinforcer choices. On the whole, the results were consistent with prior research on token-based self-control procedures in showing that choices are governed by reinforcer immediacy when exchange and food delays are unequal and by reinforcer amount when exchange and food delays are equal. Further, by decoupling the exchange delays from food delays, the results tentatively support a role for the exchange stimulus as a conditioned reinforcer.

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Two adults with mental retardation demonstrated the recombination of within-syllable units (onsets and rimes) using a spoken-to-printed-word matching-to-sample (MTS) procedure. Further testing with 1 participant showed comprehension of the printed words. Printed-word naming was minimal before, but greater after, comprehension tests. The findings suggest that these procedures hold promise for further basic and applied analyses of word-attack skills.

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