Gary M. Pace

Feature-positive and feature-negative learning in the rhesus monkey and pigeon.

In separate experiments four monkeys and eight pigeons were presented with displays containing one red and two green keys and displays containing three green keys. During feature-positive phases, responses to displays containing the one red and two green keys were reinforced on a fixed-ratio schedule, while responses to displays containing the three green keys were never reinforced. During feature-negative phases, only responses to the three green key displays were reinforced. For monkeys in Experiment 1, both between and within subject analyses indicated that the learning of feature-positive discriminations was superior to the learning of feature-negative discriminations. The within subject analysis further revealed that performance on a feature-positive discrimination was retarded following exposure to a feature-negative discrimination, while performance on a feature-negative discrimination was enhanced following exposure to a feature-positive discrimination. Experiment 2 replicated the essential aspects of these reversal effects in four experimental pigeons. Evidence that these reversal effects were not simply a function of time was provided by four control birds exposed to only a feature-positive or feature-negative discrimination.

The effects of traumatic brain injury on reporting and responding to causal relations: an investigation of sensitivity to reinforcement contingencies

Impairments in judging and responding to consequences that follow behaviour are often attributed to changes in various cognitive processes. An alternative conceptualization is that impairments may produce a reduction in sensitivity to reinforcement contingencies. The present investigation employed a methodology commonly used in research on judgements of causality to examine the effects of TBI on sensitivity to reinforcement contingencies. Participants were non-injured control subjects and adults with TBI. The experimental task required subjects to press a response key under a series of concurrent response-reinforcer contingencies that periodically delivered money for responding and not responding. Afterwards, subjects provided a judgement about each response-reinforcer contingency by reporting the amount of money earned for responding and for not responding. Results suggest that TBI reduced the sensitivity of judgements and responding under select contingencies. These results lend some support to the view that TBI may reduce sensitivity to reinforcement contingencies. Furthermore, the investigation highlights the potential benefits of employing methods commonly used in human and animal operant research for the study of TBI.

Preference for fluent versus disfluent work schedules

Two studies were conducted that examined the preference of a student diagnosed with a brain injury. In Study 1, a preference assessment was followed by a three-choice concurrent-operants reinforcer assessment. Two choices resulted in access to preferred activities for completing work, and a third choice resulted in access to nothing (i.e., no activity). Unpredictably, the participant consistently chose the no-activity option. Study 2 examined why this student preferred work associated with no activity over preferred activities. Through a variety of concurrent-operants procedures, it was determined that she preferred fluent work followed by reinforcers rather than work that was broken up by access to preferred activities. Implications for research on preference are discussed.

Effects of Behavior-Contingent and Fixed-Time Release Contingencies on Frequency and Duration of Therapeutic Restraint.

Reducing therapeutic restraint is a desirable outcome for programs that serve individuals who exhibit challenging behaviors. This study investigated the effects of modifying the criterion for release from therapeutic restraint on frequency and duration.Release from restraint was changed from a behavior-contingent criterion (restraint terminated when a specified duration of calm behavior was demonstrated) to a fixed-time criterion (restraint terminated when a predetermined duration elapsed independent of behavior) with one child and two adolescents with acquired brain injury and difficult-to-manage behaviors. For all three students, the duration of time they were exposed to therapeuticrestraint decreased with the fixed-time release criterion,whereas the frequency of restraint did not change. Practical implications of these results and future research opportunities are discussed.

Some effects of rotation and centrifugally produced high gravity on taste aversion in rats

Rats were exposed to a single pairing of grape juice and rotation or rotation plus high gravity (5 g or 10 g). They were then tested separately for grape juice consumption over the next several days. High gravity did not reduce the amount of grape juice consumed, and nonrotated controls drank significantly more throughout testing. A high resistance to extinction was evidenced by the fact that drinking suppression was maintained for the experimental groups throughout five tests.

Brief Experimental Analysis of Sight Word Interventions: A Comparison of Acquisition and Maintenance of Detected Interventions

The purpose of this study was to examine utility of a brief experimental analysis (BEA) in determining effective sight word interventions for a student with a history of difficulty with acquiring sight word recognition. Ten interventions were compared in a BEA. Following the BEA, an extended analysis was conducted that compared the two most effective interventions (from the BEA) with a control condition. Even though the BEA found two interventions to be relatively equal, one of the two interventions resulted in acquisition in half the sessions as the other intervention and this was replicated in a second extended analysis. Implications for BEA and recommendations for future research are discussed.

Relations between decision-making deficits and discriminating contingencies following brain injury

Deficits in decision-making characterized by failures to respond adaptively to consequences that follow responding are common following brain injury. To examine decision-making about consequences, individuals with and without acquired brain injury responded under different response-reinforcer contingencies. In two control conditions, reinforcement was contingent on responding and response repetition. Results showed responding (pressing four computer keys) by both groups produced similar amounts of reinforcement (money) and highlight equal sensitivity to money as a reinforcer. In subsequent experimental conditions, reinforcement was contingent upon varying responses. Results showed both groups produced variable response patterns, but injured subjects earned less reinforcement than controls. With instructions to vary responding across trials, injured subjects earned similar amounts of reinforcement as controls. Collectively, the results suggest reductions in sensitivity to contingencies may be present following injury and function as one behavioural mechanism of maladaptive decision-making.

Performance Improvement in Behavioral Health Care: Collateral Effects of Planned Treatment Integrity Observations as an Applied Example of Schedule-Induced Responding

With rising interest in the role of treatment integrity on student outcomes, research has primarily focused on isolating the techniques and procedures necessary to improve staff’s acquisition and maintenance of adequate levels of integrity. Despite increasing numbers of publications on this topic, there has been little discussion of the variables surrounding the collection of integrity data. Using an archived database of logged integrity observations at a residential school for children with brain injury, the authors sought to examine the degree to which integrity data collection conformed to best practices of behavioral assessment with respect to temporal sequencing. Moreover, due to the agency’s goal of collecting integrity on each student per month, the authors sought to examine whether the sequencing of integrity observations scalloped similarly to responding on conjunctive fixedinterval—fixed-ratio schedules. Results indicated that a majority of the staff exhibited some form of scalloping in their collection of integrity data. This article discusses possible sources of stimulus control and the potential for reactivity on the part of the teachers being observed when integrity observations are conducted in scalloped patterns. The authors conclude with a discussion on possible procedures to support the distributed collection of integrity data in applied setting.

The experimental analysis of human operant behavior following traumatic brain injury

Traumatic brain injury (TBI) may produce deficits in discriminating and responding appropriately to consequences. Commonly, insensitivity to consequences is attributed to deficits in cognitive processes, particularly executive functioning. The present investigation examined the hypothesis that TBI may reduce control exerted by reinforcers over behavior. Results of basic operant research on reinforcement processes with individuals with TBI may have clinical value for understanding and ultimately remediating deficits associated with TBI. In experiment 1, responding by adults with TBI and non-injured controls was investigated under reinforcement contingencies that differentially reinforced responding and the absence of responding within sessions. Results showed that most TBI subjects obtained lower reinforcement rates than control subjects, especially under contingencies requiring the absence of responding. In experiment 2, results showed that the addition of stimuli correlated with reinforcement improved one subjects performance. These results suggest that TBI may differentially reduce sensitivity to response-reinforcer contingencies and some environmental changes may increase sensitivity. Results also suggest parallels between deficits in executive functioning and deficits in operant behavior. Copyright

Effects of stimulus contact on the feature-positive effect.

Fourteen pigeons were taught to discriminate displays differentiated by the presence or absence of a distinctive feature. Feature-positive (FP) birds were reinforced for responses to displays containing the feature, while feature-negative (FN) birds were reinforced for responses to displays containing only the elements common to both stimulus displays. Both control and experimental birds were required to respond to a spatially separate operant key, while experimental animals were also required to contact the individual elements of the display. A planned comparisons test indicated that FP performance was superior to FN performance only for the control animals. No difference was found between the performance of the experimental FP and FN birds. Consideration of the elements of the display toward which the FN birds orient was offered as an explanation of these results.