Shaping in the 21st century: Moving percentile schedules into applied settings

The present paper provides a primer on percentile reinforcement schedules, which have been used for two decades to study response differentiation and shaping in the laboratory. Arranged in applied settings, percentile procedures could be used to specify response criteria, standardizing treatment across subjects, trainers, and times to provide a more consistent training environment while maintaining the sensitivity to the individual's repertoire that is the hallmark of shaping. Percentile schedules are also valuable tools in analyzing the variables of which responding is a function, both inside and outside the laboratory. Finally, by formalizing the rules of shaping, percentile schedules provide a useful heuristic of the processes involved in shaping behavior, even for those situations that may not easily permit their implementation. As such, they may help further sensitize trainers and researchers alike to variables of critical importance in behavior change.     

Effects of multiple versus chained schedules on stereotypy and item engagement

We evaluated rates of automatically reinforced stereotypy and item engagement for 2 children with autism under multiple and chained schedules in a multielement design. Each schedule included components during which stereotypy was blocked (S–) or allowed (S+), and we used colored cards as schedule‐correlated stimuli. We report rates of stereotypy and item engagement during S– and S+ components, as well as the percentage of component time that elapsed before the first instances of stereotypy and item engagement. We observed less stereotypy and more consistent item engagement during chained‐schedule sessions, and stimulus control of stereotypy and item engagement was established with the chained schedule. A subsequent concurrent‐chains analysis revealed participant preference for the chained schedule. These results highlight the importance of contingent access to stereotypy when therapists attempt to gain stimulus control of stereotypy and increase functional item engagement.     

双职工家庭父母工作投入对初中生学业投入的影响

基于资源保存理论,采用工作投入问卷、关系网络问卷、学业自我效能感问卷、学业投入问卷对326个双职工家庭的父母及其初中生子女进行调查,探讨父母工作投入对初中生学业投入的影响。结果表明：（1）父母工作投入、父母社会支持、子女学业自我效能感、子女学业投入两两之间呈显著正相关;（2）父母社会支持和子女学业自我效能感在父母工作投入影响子女学业投入中起中介作用;（3）父母社会支持和子女学业自我效能感的中介效应不存在显著的性别角色差异。从资源保存理论来看,父母工作投入对子女学业投入的影响,在一定程度上反映了资源在家庭系统内的投资和增益过程。     

双职工家庭父母工作投入对初中生学业投入的影响

基于资源保存理论,采用工作投入问卷、关系网络问卷、学业自我效能感问卷、学业投入问卷对326个双职工家庭的父母及其初中生子女进行调查,探讨父母工作投入对初中生学业投入的影响。结果表明：（1）父母工作投入、父母社会支持、子女学业自我效能感、子女学业投入两两之间呈显著正相关;（2）父母社会支持和子女学业自我效能感在父母工作投入影响子女学业投入中起中介作用;（3）父母社会支持和子女学业自我效能感的中介效应不存在显著的性别角色差异。从资源保存理论来看,父母工作投入对子女学业投入的影响,在一定程度上反映了资源在家庭系统内的投资和增益过程。     

Response acquisition under targeted percentile schedules: a continuing quandary for molar models of operant behavior.

The number of responses rats made in a "run" of consecutive left-lever presses, prior to a trial-ending right-lever press, was differentiated using a targeted percentile procedure. Under the nondifferential baseline, reinforcement was provided with a probability of .33 at the end of a trial, irrespective of the run on that trial. Most of the 30 subjects made short runs under these conditions, with the mean for the group around three. A targeted percentile schedule was next used to differentiate run length around the target value of 12. The current run was reinforced if it was nearer the target than 67% of those runs in the last 24 trials that were on the same side of the target as the current run. Programming reinforcement in this way held overall reinforcement probability per trial constant at .33 while providing reinforcement differentially with respect to runs more closely approximating the target of 12. The mean run for the group under this procedure increased to approximately 10. Runs approaching the target length were acquired even though differentiated responding produced the same probability of reinforcement per trial, decreased the probability of reinforcement per response, did not increase overall reinforcement rate, and generally substantially reduced it (i.e., in only a few instances did response rate increase sufficiently to compensate for the increase in the number of responses per trial). Models of behavior predicated solely on molar reinforcement contingencies all predict that runs should remain short throughout this experiment, because such runs promote both the most frequent reinforcement and the greatest reinforcement per press. To the contrary, 29 of 30 subjects emitted runs in the vicinity of the target, driving down reinforcement rate while greatly increasing the number of presses per pellet. These results illustrate the powerful effects of local reinforcement contingencies in changing behavior, and in doing so underscore a need for more dynamic quantitative formulations of operant behavior to supplement or supplant the currently prevalent static ones.     

Molecular contingencies in schedules of intermittent punishment

In two experiments, key pecking of pigeons was maintained by a variable-interval 180-s schedule of food presentation. Conjointly, a second schedule delivered response-dependent electric shock. In the first experiment, shocks were presented according to either a variable-interval or a nondifferential interval-percentile schedule. The variable-interval shock schedule differentially delivered shocks following long interresponse times. Although the nondifferential shock schedules delivered shocks less differentially with respect to interresponse times, the two shock schedules equally reduced the relative frequency of long interresponse times. The second experiment differentially shocked long or short interresponse times in different conditions, with resulting decreases in the relative frequency of the targeted interresponse times. These experiments highlight the importance of selecting the appropriate level of analysis for the interaction of behavior and environment. Orderly relations present at one level of analysis (e.g., interresponse times) may not be revealed at other levels of analysis (e.g., overall response rate).     

Using joint activity schedules to promote peer engagement in preschoolers with autism

We assessed the use of a joint activity schedule to increase peer engagement for preschoolers with autism. We taught 3 dyads of preschoolers with autism to follow joint activity schedules that cued both members of the pair to play a sequence of interactive games together. Results indicated that joint activity schedules increased peer engagement and the number of games completed for all dyads. Schedule following was maintained without additional prompting when activities were resequenced and when new games were introduced for 2 of the 3 dyads.     

Variable-ratio schedules as variable-interval schedules with linear feedback loops.

The mathematical theory of linear systems has been used successfully to describe responding on variable-interval (VI) schedules. In the simplest extension of the theory to the variable-ratio (VR) case, VR schedules are treated as if they were VI schedules with linear feedback loops. The assumption entailed by this approach, namely, that VR and VI-plus-linear-feedback schedules are equivalent, was tested by comparing responding on the two types of schedule. Four human subjects' lever pressing produced monetary reinforcers on five VR schedules, and on five VI schedules with linear feedback loops that reproduced the feedback properties of the VR schedules. Pressing was initiated by instructions in 2 subjects, and was shaped by successive approximation in the other 2. The different methods of response initiation did not have differential effects on behavior. For each of the 4 subjects, the VR and the comparable VI-plus-linear-feedback schedules generated similar average response rates and similar response patterns. The subjects' behavior on both types of schedule was similar to that of avian and rodent species on VR schedules. These results indicate that the assumption entailed by the VI-plus-linear-feedback approach to the VR case is valid and, consequently, that the approach is worth pursuing. The results also confute interresponse-time theories of schedule performance, which require interval and ratio contingencies to produce different response rates.     

Behavioral assessment of physical activity in obese preschool children

We measured changes in physical activity in 2 obese preschool children when a package intervention was evaluated in a reversal design. Physical activity was measured via direct observation and pedometers. Although the intervention produced only modest increases in activity, the results provide preliminary concurrent validation for the dependent measures used, in that the two measures covaried and a similar degree of change was observed with each across baseline and intervention phases.     

Matching and maximizing with variable-time schedules.

Pigeons were offered choices between a variable-time schedule that arranged reinforcers throughout the session and a variable-time schedule that arranged reinforcers only when the pigeon was spending time on it. The subjects could maximize the overall rate of reinforcement in this situation by biasing their time allocation towards the latter schedule. This arrangement provides an alternative to concurrent variable-interval variable-ratio schedules for testing whether animals maximize overall rates or match relative rates, and has the advantage of being free of the asymmetrical response requirements present with those schedules. The results were contrary to those predicted by maximizing: The bias it predicts did not appear.     

USING PERCENTILE SCHEDULES TO INCREASE EYE CONTACT IN CHILDREN WITH FRAGILE X SYNDROME

Aversion to eye contact is a common behavior of individuals diagnosed with Fragile X syndrome (FXS); however, no studies to date have attempted to increase eye‐contact duration in these individuals. In this study, we employed a percentile reinforcement schedule with and without overcorrection to shape eye‐contact duration of 6 boys with FXS. Results showed that although aversion to eye contact is often thought to be unamenable to change in FXS, it can be shaped in some individuals using percentile schedules either alone or in combination with overcorrection.     

Control over response number by a targeted percentile schedule: reinforcement loss and the acute effects of d-amphetamine.

Two fixed-consecutive-number-like procedures were used to examine effects of acute d-amphetamine administration on control over response number. In both procedures, rats were required to press the left lever at least once and then press the right lever to complete a trial. The consecutive left-lever presses on each trial comprised a "run." Under the targeted percentile schedule, reinforcement was provided if the current run length was closer to the target length (16) than half of the most recent 24 runs. This differentially reinforced run length while holding reinforcement probability constant at .5. A second group acquired the differentiation under the targeted percentile schedule, but were then shifted to a procedure that yoked reinforcement probability by subject and run length to that obtained under the targeted percentile schedule. The two procedures generated practically identical control run lengths, response rates, reinforcement probabilities, and reinforcement rates. Administration of d-amphetamine disrupted percentile responding to a greater degree than yoked control responding. This disruption decreased reinforcement frequency less in the former than the latter procedure. The similar baseline responding under these two procedures suggests that this difference in sensitivity was due to behavioral adjustments to drug prompted by reduction of reinforcement density in the yoked control but not the percentile schedule. These adjustments attenuate the drug's effects under the former, but not the latter, procedure.     

Decreasing student behavior problems and fostering academic engagement through function‐based support and fading of token reinforcement

This study examined the effects of function‐based behavior support plans (BSPs) on the persistent behavior problems and lack of academic engagement of three, 7‐ to 8‐year‐old, male students from two public schools in Iceland. Based on the results of functional behavioral assessments, BSPs were created for each participant. Each plan included a token system. The goal for all students was to foster independent functioning. A multiple baseline across participants showed that disruptive behavior decreased by 85% on average and academic engagement increased by 78% on average. Statistical analyses suggest significant positive effects were obtained. Findings suggest that persistent behavior problems can be reduced and independent academic engagement fostered in inclusive school settings through function‐based BSPs with gradual fading of token reinforcement.     

感知社会支持与学生学业成就关系的元分析：学习投入的中介作用

学业成就是衡量学生学习认知能力和检测其学习效果的重要指标,受到感知社会支持和学习投入等因素的显著影响,先前的研究已经考察了这两个因素对学业成就的共同作用机制,但感知社会支持与学业成就的关系强度不明,且尚不完全清楚中介效应、调节效应对二者关系的影响。因此当前研究采用元分析方法检验效应量的可靠性、学习投入的中介效应以及一系列调节效应。研究共纳入符合要求的原始文献41篇,含78个研究。结果发现：(1)感知社会支持及子类型与学业成就呈现显著的正相关,但效应值偏小,即二者之间存在的是弱相关。此外,感知社会支持及子类型显著正向预测学习投入,且对学习投入的效应量高于对学业成就的效应量。(2)学段仅对感知教师支持的调节效应显著,学业成就指标调节了感知社会支持及子类型与学业成就之间的关系,而经济水平和文化背景的调节效应不显著。(3)学习投入在感知社会支持及子类型对学业成就的影响中起到部分中介作用,且中介效应只存在于初中群体,在高中群体中介效应不显著。     

Using teacher greetings to increase speed to task engagement

We used a multiple baseline design across participants to determine if teacher greetings would reduce the latency to task engagement. Three participants were identified by their respective teachers as having difficulty initiating task-appropriate engagement at the beginning of class. Latency was measured from teacher greeting until the participant was actively engaged for 5 consecutive seconds. Results showed that teacher greetings were effective at reducing latency to task engagement for all participants.     

Preferences for token exchange‐production schedules: Effects of task difficulty and token‐production schedules

Previous research suggests that accumulated exchange‐production schedules promote increased work completion and are more preferred than distributed exchange‐production schedules. The purpose of this study was to evaluate whether the response effort or token‐production schedules associated with token delivery influenced preferences for exchange‐production schedules. Tokens exchanged under accumulated schedules were more preferred, relative to distributed schedules, when tokens were earned for completing easy tasks. When participants earned tokens for completing difficult tasks, two of three participants preferred accumulated exchange‐production schedules (Experiment 1). Under dense token‐production schedules, accumulated exchange‐production schedules were preferred, but participant's preferences switched to distributed schedules under increasing token‐production (i.e., leaner) schedules (Experiment 2).     

Matching and maximizing with concurrent ratio-interval schedules.

Animals exposed to standard concurrent variable-ratio variable-interval schedules could maximize overall reinforcement rate if, in responding, they showed a strong response bias toward the variable-ratio schedule. Tests with the standard schedules have failed to find such a bias and have been widely cited as evidence against maximization as an explanation of animal choice behavior. However, those experiments were confounded in that the value of leisure (behavior other than the instrumental response) partially offsets the value of reinforcement. The present experiment provides another such test using a concurrent procedure in which the confounding effects of leisure were mostly eliminated while the critical aspects of the concurrent variable-ratio variable-interval contingency were maintained: Responding in one component advanced only its ratio schedule while responding in the other component advanced both ratio schedules. The bias toward the latter component predicted by maximization theory was found.