Analysis of response covariationamong multiple topographies of food refusal

This study examined the effects of sequentially introducing treatment across multiple topographies of food refusal. Treatment with nonremoval of the spoon produced an increase in food acceptance and a decrease in disruption, but expulsion of food increased. When expulsion was treated, packing of food increased. Finally, when packing was treated, all refusal behaviors remained low, and acceptance continued to occur at high and stable levels.     

Identification of environmental determinants of behavior disorders through functional analysis of precursor behaviors

Experimental analysis procedures have been shown to be effective means for identifying the environmental determinants of problem behaviors. A potential limitation of these procedures is that it is necessary to produce and document patterns in the occurrence of the problem behavior during the assessment. In the case of severe behavior disorders, this may place the participant or therapist at such risk as to preclude the analysis. The current study arranged experimental analysis contingencies for precursor behaviors that had been observed to reliably precede the occurrence of problem behaviors targeted for reduction. For each of the 4 participants, it was possible to infer the maintaining variables for problem behaviors based on the outcomes of precursor analysis. These results suggest that the current procedures represent a promising alternative method for reducing risk during functional analysis of problem behaviors.     

Designing interventions that include delayed reinforcement: implications of recent laboratory research

The search for robust and durable interventions in everyday situations typically involves the use of delayed reinforcers, sometimes delivered well after a target behavior occurs. Integrating the findings from laboratory research on delayed reinforcement can contribute to the design and analysis of those applied interventions. As illustrations, we examine articles from the Journal of the Experimental Analysis of Behavior that analyzed delayed reinforcement with respect to response allocation (A. M. Williams & Lattal, 1999), stimulus chaining (B. A. Williams, 1999), and self-control (Jackson & Hackenberg, 1996). These studies help to clarify the conditions under which delayed reinforcement (a) exercises control of behavior, (b) entails conditioned reinforcement, and (c) displaces the effects of immediate reinforcement. The research has applied implications, including the development of positive social behavior and teaching people to make adaptive choices. DESCRIPTORS: delayed reinforcement, response allocation, stimulus chains, self-control, integration of basic and applied research     

The effects of response cost in the treatment of aberrant behavior maintained by negative reinforcement

Positive reinforcement contingencies can sometimes be used to decrease problem behavior maintained by negative reinforcement (e.g., escape). In the current study, we evaluated the extent to which response cost (i.e., contingent removal of a preferred stimulus) would compete with the negative reinforcer maintaining destructive behavior. The response cost contingency reduced destructive behavior by 87% from baseline levels even though the negative reinforcement contingency (i.e., escape) remained in place.     

Interaction of procedural factors in human performance on yoked schedules

The differential effects of reinforcement contingencies and contextual variables on human performance were investigated in two experiments. In Experiment 1, adult human subjects operated a joystick in a video game in which the destruction of targets was arranged according to a yoked variable-ratio variable-interval schedule of reinforcement. Three variables were examined across 12 conditions: verbal instructions, shaping, and the use of a consummatory response following reinforcement (i.e., depositing a coin into a bank). Behavior was most responsive to the reinforcement contingencies when the consummatory response was available, responding was established by shaping, and subjects received minimal verbal instructions about their task. The responsiveness of variable-interval subjects' behavior varied more than that of variable-ratio subjects when these contextual factors were altered. Experiment 2 examined resistance to instructional control under the same yoked-schedules design. Conditions varied in terms of the validity of instructions. Performance on variable-ratio schedules was more resistant to instructional control than that on variable-interval schedules.     

Effect of drugs on response-duration differentiation VII: response-force requirements

Rats were trained to press a lever for at least 1 s but for less than 1.3 s. The force required to press the lever was then increased or decreased by 10, 15, or 20 g. Increases in the force requirements for lever pressing decreased timing accuracy, but decreases in the force requirement had the opposite effect. Accuracy decreases at increasing force requirements were characterized by an increase in the relative frequency of responses that were too short to meet the reinforcement criterion. In contrast, increases in accuracy when the force requirements were decreased were characterized by increases in response durations that met the reinforcement criterion and decreases in the relative frequency of responses that were too short to produce the reinforcer. Phencyclidine (PCP) and methamphetamine produced dose-dependent decreases in accuracy that were associated primarily with increases in the relative frequency of short response durations, although methamphetamine also produced increases in long response durations at some doses. When the effects of PCP were determined with the force requirement increased by 10 g or decreased by 15 g, the cumulative response-duration distribution shifted toward even shorter response durations. When the effects of methamphetamine were determined with the force requirement on the lever increased by 10 g, the cumulative frequency distribution was shifted toward shorter response durations to about the same extent as it had been before force requirements increased; however, when the force required to press the lever was decreased by 15 g, these shifts toward shorter response durations almost completely disappeared. These results show that increases and decreases in the force requirements for lever pressing have different effects on the accuracy of temporal response differentiation.     

Studies of wheel-running reinforcement: parameters of Herrnstein's (1970) response-strength equation vary with schedule order

Six male Wistar rats were exposed to different orders of reinforcement schedules to investigate if estimates from Herrnstein's (1970) single-operant matching law equation would vary systematically with schedule order. Reinforcement schedules were arranged in orders of increasing and decreasing reinforcement rate. Subsequently, all rats were exposed to a single reinforcement schedule within a session to determine within-session changes in responding. For each condition, the operant was lever pressing and the reinforcing consequence was the opportunity to run for 15 s. Estimates of k and R(O) were higher when reinforcement schedules were arranged in order of increasing reinforcement rate. Within a session on a single reinforcement schedule, response rates increased between the beginning and the end of a session. A positive correlation between the difference in parameters between schedule orders and the difference in response rates within a session suggests that the within-session change in response rates may be related to the difference in the asymptotes. These results call into question the validity of parameter estimates from Herrnstein's (1970) equation when reinforcer efficacy changes within a session.     

On the use of heterogeneous thresholds ordinal regression models to account for individual differences in response style

This paper proposes a general approach to accounting for individual differences in the extreme response style in statistical models for ordered response categories. This approach uses a hierarchical ordinal regression modeling framework with heterogeneous thresholds structures to account for individual differences in the response style. Markov chain Monte Carlo algorithms for Bayesian inference for models with heterogeneous thresholds structures are discussed in detail. A simulation and two examples based on ordinal probit models are given to illustrate the proposed methodology. The simulation and examples also demonstrate that failing to account for individual differences in the extreme response style can have adverse consequences for statistical inferences.The author is grateful to Ulf Böckenholt, an associate editor, and three anonymous reviewers for helpful comments, and Kristine Kuhn and Kshiti Joshi for providing the data.     

The effect of methylphenidate on three forms of response inhibition in boys with AD/HD

The current study was aimed at (a) investigating the effect of three doses methylphenidate (MPH) and placebo on inhibition of a prepotent response, inhibition of an ongoing response, and interference control in Attention Deficit/Hyperactivity Disorder (AD/HD), and (b) studying dose-response relations for the three forms of response inhibition. To meet these aims, the following tasks were selected: two versions of the Stop Paradigm for inhibition of a prepotent response, a Circle Tracing Task and a recently developed Follow Task for inhibition of an ongoing response, and the Stroop Color-Word Test and an Eriksen Flanker Task for interference control. These tasks were administered to 23 boys with AD/HD during four treatment conditions: 5 mg MPH, 10 mg MPH, 20 mg MPH, and placebo. A pseudorandomized, multiple-blind, placebo-controlled, within-subject design was used. As hypothesized, inhibitory control in children with AD/HD improved under MPH compared to placebo. However, this effect was only significant for inhibition of a prepotent response and inhibition of an ongoing response (as measured by the Follow Task), but not for interference control. The relation between treatment condition and response was linear. However, this linear relation was due to improved inhibitory control under MPH compared to placebo, because no effects of MPH dose were observed for any of the response inhibition measures.     

Accuracy of discrimination,rate of responding,and resistance to change

Pigeons were trained on multiple schedules in which responding on a center key produced matching-to-sample trials according to the same variable-interval 30-s schedules in both components. Matching trials consisted of a vertical or tilted line sample on the center key followed by vertical and tilted comparisons on the side keys. Correct responses to comparison stimuli were reinforced with probability .80 in the rich component and .20 in the lean component. Baseline response rates and matching accuracies generally were higher in the rich component, consistent with previous research. When performance was disrupted by prefeeding, response-independent food during intercomponent intervals, intrusion of a delay between sample and comparison stimuli, or extinction, both response rates and matching accuracies generally decreased. Proportions of baseline response rate were greater in the rich component for all disrupters except delay, which had relatively small and inconsistent effects on response rate. By contrast, delay had large and consistent effects on matching accuracy, and proportions of baseline matching accuracy were greater in the rich component for all four disrupters. The dissociation of response rate and accuracy with delay reflects the localized impact of delay on matching performance. The similarity of the data for response rate and accuracy with prefeeding, response-independent food, and extinction shows that matching performance, like response rate, is more resistant to change in a rich than in a lean component. This result extends resistance to change analyses from the frequency of response emission to the degree of stimulus control, and suggests that the strength of discriminating, like the strength of responding, is positively related to rate of reinforcement.