Dean C. Williams

Effects of risperidone on Aberrant behavior of persons with developmental disabilities: I. A double-blind crossover study using multiple measures

The efficacy of the atypical antipsychotic risperidone was evaluated in the treatment of aberrant behavior (e.g., aggression, self-injury) in 20 individuals with developmental disabilities. A double-blind, crossover design was used to compare risperidone with placebo in a 22-week trial with a 6-month follow-up phase. Based on a 50% reduction in mean Aberrant Behavior Checklist--Community total scores, 50% of the participants were identified as responders. Naturalistic observations of a subset of five individuals showed that for 4 out of 5 participants, risperidone was effective in reducing aberrant behavior. Side effects included weight gain (84% of participants) and sedation (40% of participants). The advantages of conducting a comprehensive analysis of the effects of medication on aberrant behavior are discussed.

An Interaction of Instructions and Training Design on Stimulus Class Formation: Extending the Analysis of Equivalence

Our previous research with subjects with mild mental retardation indicated different outcomes on stimulus equivalence tests when different training designs were employed. Subjects exposed to match-to-sample training involving four pairs of sample stimuli and one pair of comparisons (comparison as node) were more likely to show positive results on equivalence tests than subjects trained with four pairs of comparisons and one pair of samples (sample as node). We describe three studies aimed at analyzing the superiority of the comparison-as-node training procedure. The results suggest that (a) preexperimental individual differences and subject assignment do not account for the previous findings, (b) the greater effectiveness of the comparison-as-node procedure may be caused partially by an interaction of the procedure and instructions providing stimulus names, and (c) differential outcomes on equivalence tests with these training procedures may be demonstrated only with developmentally limited subjects. Several theoretical interpretations for the reason the comparison-as-node training method is more likely to produce positive equivalence test performances and the implication of these interpretations for understanding stimulus equivalence in general are discussed.

Stimulus-Control Procedures

The term stimulus control refers to “any difference in responding in the presence of different stimuli” (Catania, 1992, p. 372). Virtually all of the behavior in our everyday lives involves stimulus control. When a driver approaches a red light, he puts his foot on the brake pedal. When approaching a green light, he keeps his foot on the gas pedal. The driver’s responses are thus under the stimulus control of the light’s color. Analyzing existing stimulus control and analyzing the development and stability of stimulus-control relations are central to the understanding of normal and abnormal human behavior. Moreover, much of experimental psychology involves the study of stimulus control. Issues addressed under the rubrics of learning, concept formation, memory, and sensory processes usually involve differences in responding in the presence of different stimuli, and thus involve issues of stimulus control. In addition, stimulus-control procedures are used to generate behavioral baselines for the study of the effects of drugs or other physiological manipulations. As such, stimulus-control procedures are discussed throughout this volume.

6 Derived stimulus control: Are there differences among procedures and processes?*

Publisher Summary The chapter describes procedures to demonstrate derived stimulus control and to classify them based on structure. It discusses the relationship among the various training structures and the likelihood of demonstrating stimulus classes in humans and animals. It also notes procedural differences that might affect the likelihood of demonstrating derived stimulus control within a particular training structure. There is more than one type of transfer involved in the stimulus class literature, and some species are limited to unidirectional transfer that essentially involves the recombination of chains: Pigeons demonstrate unidirectional transfer that may not involve symmetry or transitivity. They also demonstrate transfer that can be mediated by behaviors that occur between the presentation of the sample stimulus and the response to the comparison stimulus. Moreover, such intervening behaviors play different roles for pigeons than for human subjects. Pigeons are yet to demonstrate nonmediated symmetry or equivalence.

Multimodal evaluation of risperidone for destructive behavior: functional analysis, direct observations, rating scales, and psychiatric impressions.

Risperidone, an atypical neuroleptic, has become a popular option for treating destructive behaviors of persons with developmental disabilities. A few studies have been conducted that evaluate the effects of risperidone on destructive behavior; however, none of these studies have combined objective measures with rating scales to evaluate the effects of risperidone on destructive behavior across home and clinical settings. This study evaluated the wide range of effects of risperidone on destructive behavior of 2 persons with developmental disabilities using weekly functional analysis sessions, daily observations, hourly home data, weekly rating scales, and monthly psychiatric impressions. Results indicate that risperidone does decrease destructive behavior and that, for the most part, all of the various measures yielded similar results.

Drug-behavior interactions in persons with mental retardation and developmental disabilities

Treatment for aberrant behavior in persons diagnosed with developmental disabilities typically involves either behavioral interventions or medication. Often, the treatment is a combination of the two. Schroeder and coworkers (Schroeder et al. [1983] Adv Learn Behav Disabil 2:179–225) outlined criteria for the evaluation of the combination of behavioral and drug interventions in persons with developmental disabilities. A review of the research that examined the combination of drug and behavior interactions since 1983, using the Schroeder et al. criteria, is provided. An evaluation of research since 1983 that examined medication effects on multiple dependent measures and between multiple medications, using the criteria for medication research by Sprague and Werry (Sprague and Werry [1971] Int Rev Res Ment Retard vol. 5) is also provided. Additionally, the final section provides a list of recommendations and criteria for practitioners and researchers when conducting or evaluating research designed to examine medication effects on multiple variables in persons with developmental disabilities. MRDD Research Reviews 1999;5:322–334.

EVALUATION OF STIMULUS CONTROL OVER A COMMUNICATION RESPONSE AS AN INTERVENTION FOR STEREOTYPICAL RESPONDING

Stereotypical behavior maintained by automatic reinforcement often does not result in harm but may be undesirable in some situations. In the current investigation, participants were 2 individuals who engaged in nonharmful stereotypical responses shown in an analogue functional analysis to be insensitive to social contingencies. After bringing these responses under stimulus control using differential punishment, both participants learned a mand to terminate punishment for stereotypy. We also assessed whether the mand could be brought under stimulus control.

Generalized Identity Matching of Two-Dimensional Forms by Individuals With Moderate to Profound Mental Retardation

The classic literature suggests that individuals with MAs of less than 5 years may fail tasks that require same/different judgments. In Study 1 we used an assessment procedure that provided minimal instructional programming to determine whether 17 adults with MAs ranging from 2 years, 5 months to 4 years, 11 months would show accurate identity matching-to-sample. Stimuli were letter-like nonsense forms. Eight participants showed highly accurate matching. Eight of the 9 who failed were available for further study. Of these, 5 ultimately demonstrated highly accurate matching after training with standard fading procedures. These data suggest that a greater proportion of individuals with low MAs can exhibit generalized identity matching than previously documented in the literature.

Conditional versus trial-unique delayed matching-to-sample.

We compared performance on conditional and trial-unique delayed identity matching-to-sample procedures. In Experiment 1, participants with moderate to severe mental retardation were exposed to both procedures under a single, brief delay value. Three of 5 subjects showed higher accuracy in the trial-unique sessions. In Experiment 2, participants with mild mental retardation were exposed to delay values of 0, 2, 4, 8, and 16 seconds, randomized within each session. For 3 of 4 subjects, accuracy was highest with trial-unique, and lowest on the conditional matching-to-sample, at longer delays. Across the two studies, 6 of 9 subjects showed lower delayed matching accuracy when fewer rather than more stimuli were included in a session.

Aversive properties of negative incentive shifts in Fischer 344 and Lewis rats

&NA; Research on incentive contrast highlights that reward value is not absolute but rather is based upon comparisons we make to rewards we have received and expect to receive. Both human and nonhuman studies on incentive contrast show that shifting from a larger more‐valued reward to a smaller less‐valued reward is associated with long periods of nonresponding – a negative contrast effect. In this investigation, we used two different genetic rat strains, Fischer 344 and Lewis rats that putatively differ in their sensitivity to aversive stimulation, to assess the aversive properties of large‐to‐small reward shifts (negative incentive shifts). Additionally, we examined the extent to which increasing cost (fixed‐ratio requirements) modulates negative contrast effects. In the presence of a cue that signaled the upcoming reward magnitude, lever pressing was reinforced with one of two different magnitudes of food (large or small). This design created two contrast shifts (small‐to‐large, large‐to‐small) and two shifts used as control conditions (small‐to‐small, large‐to‐large). Results showed a significant interaction between rat strain and cost requirements only during the negative incentive shift with the emotionally reactive Fischer 344 rats exhibiting significantly longer response latencies with increasing cost, highlighting greater negative contrast. These findings are more consistent with emotionality accounts of negative contrast and results of neurophysiological research that suggests shifting from a large to a small reward is aversive. Findings also highlight how subjective reward value and motivation is a product of gene‐environment interactions. HIGHLIGHTSNegative incentive contrast is characterized by increased response latencies for an upcoming small reward when preceded by a larger reward.We evaluated the aversive properties of negative incentive contrast using an operant, simultaneous contrast paradigm.Fischer 344 and Lewis rats were exposed to incentive shifts across a range of fixed‐ratios (costs).Fischer 344 rats showed greater negative incentive contrast than Lewis rats and cost‐modulated effects.Negative incentive shifts may elicit negative affective responses in line with emotionality accounts of negative incentive contrast.