NONCONTINGENT REINFORCEMENT: A FURTHER EXAMINATION OF SCHEDULE EFFECTS DURING TREATMENT

We conducted 2 studies to determine whether dense and thin NCR schedules exert different influences over behavior and whether these influences change as dense schedules are thinned. In Study 1, we observed that thin as well as dense NCR schedules effectively decreased problem behavior exhibited by 3 individuals. In Study 2, we compared the effects of 2 NCR schedules in multielement designs, one with and the other without an extinction (EXT) component, while both schedules were thinned. Problem behavior remained low as the NCR schedule with EXT was thinned, but either (a) did not decrease initially or (b) subsequently increased as the NCR schedule without EXT was thinned. These results suggest that dense schedules of NCR decrease behavior by altering its motivating operation but that extinction occurs as the NCR schedule is thinned. The benefits and limitations of using dense or thin NCR schedules are discussed.     

Additional free reinforcers increase persistence of problem behavior in a clinical context: A partial replication of laboratory findings

Behavioral momentum theory is a quantitative framework used to characterize the persistence of behavior during response disruptors as a function of baseline stimulus–reinforcer relations. Results of several investigations have shown that alternative reinforcement can increase the resistance to change of a target response during extinction. In the present study, concomitant variable‐interval fixed‐time schedules of reinforcement for problem behavior were employed to simulate naturalistic situations involving the superimposition of response‐independent reinforcers on a baseline schedule of reinforcement for problem behavior, as in the common use of noncontingent reinforcement treatments. Resistance to change of problem behavior was assessed during postsession periods of extinction by comparing response rates in extinction following sessions with and without additional reinforcer deliveries arranged by fixed‐time schedules. For 2 out of 3 participants, problem behavior tended to be more resistant to extinction following periods in which additional fixed‐time reinforcers were delivered. These results are discussed in terms of potential effects of noncontingent reinforcement on problem behavior when the intervention is discontinued or implemented without good treatment integrity.     

Multiple schedules in practical application: Research trends and implications for future investigation

Researchers began studying multiple schedules in basic laboratories, but recent advances have extended research on multiple schedules to a wide variety of socially significant applications, especially during the last decade. Applied researchers have used multiple schedules to (a) promote stimulus control over high‐rate appropriate behaviors, (b) thin the schedule of reinforcement following functional communication training, and (c) obtain stimulus control over problem behaviors maintained by automatic reinforcement. In the current paper, we reviewed 31 studies with 147 applications identified through a search of the applied literature on multiple schedules. Using these studies, we (a) reviewed the empirical literature on multiple schedules, (b) recommended multiple‐schedule procedures that serve as best practice guidelines for applied behavior analysts, (c) identified the generality and boundaries of current knowledge about the effectiveness of multiple schedules, and (d) critically analyzed the literature to provide directions for future multiple‐schedule research.     

Variable-time reinforcement schedules in the treatment of socially maintained problem behavior

Noncontingent reinforcement (NCR) consists of delivering a reinforcer on a time-based schedule, independent of responding. Studies evaluating the effectiveness of NCR as treatment for problem behavior have used fixed-time (FT) schedules of reinforcement. In this study, the efficacy of NCR with variable-time (VT) schedules was evaluated by comparing the effects of VT and FT reinforcement schedules with 2 individuals who engaged in problem behavior maintained by positive reinforcement. Both FT and VT schedules were effective in reducing problem behavior. These findings suggest that VT schedules can be used to treat problem behavior maintained by social consequences.     

RESPONDING MAINTAINED BY INTERMITTENT REINFORCEMENT: IMPLICATIONS FOR THE USE OF EXTINCTION WITH PROBLEM BEHAVIOR IN CLINICAL SETTINGS

Results of basic research have demonstrated that behavior maintained on an intermittent schedule of reinforcement (INT) will be extinguished more slowly than behavior maintained on a continuous schedule (CRF). Although these findings suggest that problem behaviors may be difficult to treat with extinction if they have been maintained on INT rather than on CRF schedules, few applied studies have examined this phenomenon with human behavior in clinical settings. The purpose of this study was to determine whether problem behavior maintained on CRF schedules would be extinguished more rapidly than behavior maintained on INT schedules. Three individuals diagnosed with profound mental retardation participated after results of pretreatment functional analyses had identified the sources of reinforcement that were maintaining their self-injury, aggression, or disruption. Subjects were exposed to extinction following baseline conditions with CRF or INT schedules alternated within reversal or multielement designs. Results suggested that problem behaviors may not be more difficult to treat with extinction if they have been maintained on INT rather than CRF schedules. However, switching from an INT to a CRF schedule prior to extinction may lower the baseline response rate as well as the total number of responses exhibited during extinction.     

EFFECTS OF INTERMITTENT PUNISHMENT ON SELF-INJURIOUS BEHAVIOR: AN EVALUATION OF SCHEDULE THINNING

Although the use of punishment often raises ethical issues, such procedures may be needed when the reinforcers that maintain behavior cannot be identified or controlled, or when competing reinforcers cannot be found. Results of several studies on the effects of intermittent schedules of punishment suggest that therapists must use fairly rich schedules of punishment to suppress problem behavior. However, residential caretakers, teachers, and parents often have difficulty implementing programs that require constant monitoring of the client's behavior. In this study, we examined the feasibility of gradually thinning the delivery of punishment from a continuous schedule to an intermittent schedule during the course of treatment for self-injurious behavior (SIB). Results of functional analyses for 5 individuals who had been diagnosed with profound mental retardation indicated that their SIB was not maintained by social consequences. Treatment with continuous schedules of time-out (for 1 participant) or contingent restraint (for the other 4 participants) produced substantial reductions in SIB. When they were exposed to intermittent schedules of punishment (fixed-interval [FI] 120 s or FI 300 s), SIB for all but 1 of the participants increased to levels similar to those observed during baseline. For these 4 participants, the schedule of punishment was gradually thinned from continuous to FI 120 s or FI 300 s. For 2 participants, SIB remained low across the schedule changes, demonstrating the utility of thinning from continuous to intermittent schedules of punishment. Results for the other 2 participants showed that intermittent punishment was ineffective, despite repeated attempts to thin the schedule.     

EFFECTS OF A FIXED‐TIME SCHEDULE ON ABERRANT AND ADAPTIVE BEHAVIOR

Fixed‐time (FT) schedules of reinforcement have been used to decrease destructive behavior. However, the effects of FT schedules on acquisition and maintenance of appropriate behavior remain unclear. In this study, we present a case in which an FT schedule produced an increase in adaptive behavior and resulted in a significant decrease in destructive behavior.     

Effects of signaling on temporal control of behavior in response‐initiated fixed intervals

Behavior and events distributed in time can serve as markers that signal delays to future events. The majority of timing research has focused on how behavior changes as the time to some event, usually food availability, decreases. The primary objective of the two experiments presented here was to assess how behavior changes as time passes between two time markers when the first time marker was manipulated but the second, food delivery, was held constant. Pigeons were exposed to fixed‐interval, response‐initiated fixed‐interval, and signaled response‐initiated fixed‐interval 15‐ and 30‐s schedules of reinforcement. In Experiment 1, first‐response latencies were systematically shorter in the signaled response‐initiated schedules than response‐initiated schedules, suggesting that the first response was a more effective time marker when it was signaled. In Experiment 2, responding in no‐food (i.e. “peak”) trials indicated that timing accuracy was equivalent in the three schedule types. Compared to fixed interval schedules, timing precision was reduced in the signaled response‐initiated schedules and was lowest in response‐initiated schedules. Results from Experiments 1 and 2 coupled with previous research suggest that the overall “informativeness” of a time marker relative to other events and behaviors in the environment may determine its efficacy.     

USING FIXED‐TIME SCHEDULES TO MAINTAIN BEHAVIOR: A PRELIMINARY INVESTIGATION

The purpose of this study was to evaluate the potential of fixed‐time (FT) schedules to maintain behavior. Two children who had been diagnosed with autism were taught a functional task. Subsequently, three different FT schedules (i.e., yoked, thin, dense) were compared to determine their capacity to maintain task responding. Results suggested that FT schedules may be used to maintain previously acquired behavior.     

A comparison of dense-to-lean and fixed lean schedules of alternative reinforcement and extinction

Behavior-reduction interventions typically employ dense schedules of alternative reinforcement in conjunction with operant extinction for problem behavior. After problem behavior is reduced in the initial treatment stages, schedule thinning is routinely conducted to make the intervention more practical in natural environments. In the current investigation, two methods for thinning alternative reinforcement schedules were compared for 3 clients who exhibited severe problem behavior. In the dense-to-lean (DTL) condition, reinforcement was delivered on relatively dense schedules (using noncontingent reinforcement for 1 participant and functional communication training for 2 participants), followed by systematic schedule thinning to progressively leaner schedules. During the fixed lean (FL) condition, reinforcement was delivered on lean schedules (equivalent to the terminal schedule of the DTL condition). The FL condition produced a quicker attainment of individual treatment goals for 2 of the 3 participants. The results are discussed in terms of the potential utility of using relatively lean schedules at treatment outset.     

Functional communication during signaled reinforcement and/or extinction

Schedule thinning following functional communication training (FCT) can increase treatment feasibility. Multiple‐schedule arrangements are often used in this process; however, the current literature provides little information on the optimum signal arrangements. In the current study, we examined the effects of three signal arrangements (i.e., signaled FR1, signaled EXT, and signaled FR1/EXT) on rates of problem behavior at dense schedule values and during schedule thinning. At all schedule values, signaled FR1/EXT controlled collateral behavior better than did signaled FR1 or signaled EXT. Additionally, for the single signal arrangements, the signaled FR1 was more efficient than the signaled EXT at dense schedules whereas the inverse was true at leaner schedules. Copyright © 2009 John Wiley & Sons, Ltd.     

Effects of adjusting DRO schedules on the reduction of stereotypic vocalizations in children with autism

The reduction of stereotypic behavior is important for individuals with developmental disabilities because it may interfere with learning new skills. A common procedure used to reduce stereotypic behavior is differential reinforcement of other behavior (DRO). A DRO schedule is a procedure in which reinforcement is delivered given the absence of a target response for a period of time. Although DRO schedules have been shown to be effective in reducing a variety of stereotypic behavior, empirical studies have not yet determined the most effective way to thin the reinforcement schedule. The current study examined the extent to which the relationship between the inter‐response time (IRT) and the DRO requirement affects the reduction of stereotypic behavior. Results of the current study showed the DRO requirement that was set to the 25th percentile of the IRT distribution was more effective in reducing stereotypic behavior when compared with a DRO requirement set to the 95th percentile of the IRT distribution. Copyright © 2009 John Wiley & Sons, Ltd.     

Hill-climbing by pigeons

Pigeons were exposed to two types of concurrent operant-reinforcement schedules in order to determine what choice rules determine behavior on these schedules. In the first set of experiments, concurrent variable-interval, variable-interval schedules, key-peck responses to either of two alternative schedules produced food reinforcement after a random time interval. The frequency of food-reinforcement availability for the two schedules was varied over different ranges for different birds. In the second series of experiments, concurrent variable-ratio, variable-interval schedules, key-peck responses to one schedule produced food reinforcement after a random time interval, whereas food reinforcement occurred for an alternative schedule only after a random number of responses. Results from both experiments showed that pigeons consistently follow a behavioral strategy in which the alternative schedule chosen at any time is the one which offers the highest momentary reinforcement probability (momentary maximizing). The quality of momentary maximizing was somewhat higher and more consistent when both alternative reinforcement schedules were time-based than when one schedule was time-based and the alternative response-count based. Previous attempts to provide evidence for the existence of momentary maximizing were shown to be based upon faulty assumptions about the behavior implied by momentary maximizing and resultant inappropriate measures of behavior.     

Effects of continuous and intermittent reinforcement for problem behavior during functional communication training

We evaluated the effectiveness of functional communication training (FCT) in reducing problem behavior and in strengthening alternative behavior when FCT was implemented without extinction. Following the completion of functional analyses in which social-positive reinforcement was identified as the maintaining variable for 5 participants' self-injurious behavior (SIB) and aggression, the participants were first exposed to FCT in which both problem behavior and alternative behavior were reinforced continuously (i.e., on fixed-ratio [FR] 1 schedules). During subsequent FCT conditions, the schedule of reinforcement for problem behavior was made more intermittent (e.g., FR 2, FR 3, FR 5, etc.), whereas alternative behavior was always reinforced according to an FR 1 schedule. Results showed that 1 participant's problem behavior decreased and alternative behavior increased during FCT when both behaviors were reinforced on FR 1 schedules. The remaining 4 participants shifted response allocation from problem to alternative behavior as the schedule of reinforcement for problem behavior became more intermittent. These results suggest that individuals might acquire alternative responses during FCT in spite of inconsistencies in the application of extinction, although even small errors in reinforcement may compromise treatment effects.     

Assessing reinforcers under progressive schedule requirements.

Recent research findings suggest that reinforcing stimuli may be differentially effective as response requirements increase. We extended this line of research by evaluating responding under increasing schedule requirements via progressive‐ratio schedules and behavioral economic analyses. The differential effectiveness of preferred stimuli in treating destructive behavior maintained by automatic reinforcement also was examined. Results showed that one of two stimuli was associated with more responding under increasing schedule requirements for the 4 participants. Furthermore, stimuli associated with more responding under increasing schedule requirements generally were more effective in treating destructive behavior than stimuli associated with less responding. These data suggest that progressive‐ratio schedules and behavioral economic analyses may be useful for developing a new technology for reinforcer identification. From a clinical perspective, these results suggest that two reinforcers may be similarly effective for low‐effort tasks and differentially effective for high‐effort tasks.     

Noncontingent reinforcement without extinction plus differential reinforcement of alternative behavior during treatment of problem behavior

The effects of noncontingent reinforcement (NCR) without extinction during treatment of problem behavior maintained by social positive reinforcement were evaluated for five individuals diagnosed with autism spectrum disorder. A continuous NCR schedule was gradually thinned to a fixed‐time 5‐min schedule. If problem behavior increased during NCR schedule thinning, a continuous NCR schedule was reinstated and NCR schedule thinning was repeated with differential reinforcement of alternative behavior (DRA) included. Results showed an immediate decrease in all participants’ problem behavior during continuous NCR, and problem behavior maintained at low levels during NCR schedule thinning for three participants. Problem behavior increased and maintained at higher rates during NCR schedule thinning for two other participants; however, the addition of DRA to the intervention resulted in decreased problem behavior and increased mands.     

Cooperative responding in rats maintained by fixed‐ and variable‐ratio schedules

The present study investigated the effects of fixed‐ratio (FR) and variable‐ratio (VR) reinforcement schedules on patterns of cooperative responding in pairs of rats. Experiment 1 arranged FR 1, FR 10, and VR 10 schedules to establish cooperative responding (water delivery depended on the joint responding of two rats). Cooperative response rates and proportions were higher under intermittent schedules than under continuous reinforcement. The FR 10 schedule generated a break‐and‐run pattern, whereas the VR 10 schedule generated a relatively high and constant rate pattern. Experiment 2 evaluated the effects of parametric manipulations of FR and VR schedules on cooperative responding. Rates and proportions of cooperative responding generally increased between ratio sizes of 1 and 5 but showed no consistent trend as the ratio increased from 5 to 10. Experiment 3 contrasted cooperative responding between an FR6 schedule and a yoked control schedule. Coordinated behavior occurred at a higher rate under the former schedule. The present study showed that external consequences and the schedules under which the delivery of these consequences are based, select patterns of coordinated behavior.     

SINGLE‐SAMPLE DISCRIMINATION OF DIFFERENT SCHEDULES' REINFORCED INTERRESPONSE TIMES

Food‐deprived rats in Experiment 1 responded to one of two tandem schedules that were, with equal probability, associated with a sample lever. The tandem schedules' initial links were different random‐interval schedules. Their values were adjusted to approximate equality in time to completing each tandem schedule's response requirements. The tandem schedules differed in their terminal links: One reinforced short interresponse times; the other reinforced long ones. Tandem‐schedule completion presented two comparison levers, one of which was associated with each tandem schedule. Pressing the lever associated with the sample‐lever tandem schedule produced a food pellet. Pressing the other produced a blackout. The difference between terminal‐link reinforced interresponse times varied across 10‐trial blocks within a session. Conditional‐discrimination accuracy increased with the size of the temporal difference between terminal‐link reinforced interresponse times. In Experiment 2, one tandem schedule was replaced by a random ratio, while the comparison schedule was either a tandem schedule that only reinforced long interresponse times or a random‐interval schedule. Again, conditional‐discrimination accuracy increased with the temporal difference between the two schedules' reinforced interresponse times. Most rats mastered the discrimination between random ratio and random interval, showing that the interresponse times reinforced by these schedules can serve to discriminate between these schedules.     

Comparing fixed‐amount and progressive‐amount DRO Schedules for tic suppression in youth with chronic tic disorders

Chronic tic disorders (CTDs) involve motor and/or vocal tics that often cause substantial distress and impairment. Differential reinforcement of other behavior (DRO) schedules of reinforcement produce robust, but incomplete, reductions in tic frequency in youth with CTDs; however, a more robust reduction may be needed to affect durable clinical change. Standard, fixed‐amount DRO schedules have not commonly yielded such reductions, so we evaluated a novel, progressive‐amount DRO schedule, based on its ability to facilitate sustained abstinence from functionally similar behaviors. Five youth with CTDs were exposed to periods of baseline, fixed‐amount DRO (DRO‐F), and progressive‐amount DRO (DRO‐P). Both DRO schedules produced decreases in tic rate and increases in intertic interval duration, but no systematic differences were seen between the two schedules on any dimension of tic occurrence. The DRO‐F schedule was generally preferred to the DRO‐P schedule. Possible procedural improvements and other future directions are discussed.     

Children's preference for mixed‐ versus fixed‐ratio schedules of reinforcement: A translational study of risky choice

Laboratory research has shown that when subjects are given a choice between fixed‐ratio and bi‐valued mixed‐ratio schedules of reinforcement, preference typically emerges for the mixed‐ratio schedule even with a larger ratio requirement. The current study sought to replicate and extend these findings to children's math problem completion. Using an ABCBC reversal design, four fourth‐grade students were given the choice of completing addition problems reinforced on either a fixed‐ratio 5 schedule or one of three mixed‐ratio schedules; an equivalent mixed‐ratio (1, 9) schedule, a mixed‐ratio (1, 11) schedule with a 20% larger ratio requirement, and an equally lean mixed‐ratio (5, 7) schedule without the small fixed‐ratio 1 component. This was followed by a reversal back to the preceding phase in which preference for the mixed‐ratio schedule had been observed, and a final reversal back to the mixed‐ratio (5, 7) phase. Findings were consistent with previous research in that all children preferred the mixed‐ratio (1, 9) schedule over the equivalent fixed‐ratio 5 schedule. Preference persisted for the leaner mixed‐ratio (1, 11) schedule for three of the four children. Indifference or preference for the fixed‐ratio 5 alternative was observed in phases containing the mixed‐ratio (5, 7) schedule. These results extend previous research on risky choice to children's math problem completion and highlight the importance of a small ratio component in the emergence of preference for bi‐valued mixed‐ratio schedules. Implications of these results for arranging reinforcement to increase children's academic responding are discussed.