Percentile Schedule Research Articles

Inter-response time shaping by percentile schedule with discrete trial procedure

The percentile schedule has been used as a convenient procedure for the automatic shaping of operant responses. Experiments 1, 2, and 4 of this study examined whether two variables related to the percentile schedule—“update the reinforcement criterion for each response” and “retreat of the reinforcement criterion”—are critical factors of the percentile schedule on shaping. Experiment 3 examined the effect of combining one of the shaping rule “reinforce movement, not position” with the percentile schedule. Eight pigeons were exposed to a discrete trial procedure. In each trial, pigeons were required to peck one key and then to the other, and the interval between pecks was defined as the inter-response time (IRT). A percentile schedule was applied to this IRT aiming to lengthen it. The results showed that (1) IRTs were lengthened by the percentile schedule; (2) "update the reinforcement criterion for each response," "retreat of the reinforcement criterion," and "reinforce movement, not position" had no significant effect on lengthening IRT; and (3) the frequency of IRT occurrence decreased when the "retreat of the reinforcement criterion" was removed. These results indicate that the aforementioned percentile schedule variables are not critical for the percentile schedule on IRT shaping. Because the discrete trial procedure can dissociate the effects of variables on the length and frequency of IRT, this procedure seems effective for future shaping studies.

Escalating schedules of incentives increase physical activity with no differences between deposit and no-deposit groups: A systematic replication.

Physical inactivity has increasingly affected public health in the United States during the COVID-19 pandemic as it is associated with chronic diseases such as arthritis, cancer, and heart disease. Contingency management has been shown to increase physical activity. Therefore, the present study sought to evaluate the effects of an escalating schedule of monetary reinforcement with a reset contingency on physical activity, as compared between 2 counterbalanced groups in which a monetary deposit of $25 was either required (deposit group) or not (no-deposit group). Twenty-five adults wore Fitbit accelerometers to monitor step counts. An ABA reversal design was used; in the 2 baseline phases, no programmed contingencies were in place for step counts. During intervention, step goals were set using a modified 70th percentile schedule with a 7-day window: Reaching the first goal would result in $0.25, and incentives increased by $0.25 for each subsequent day in which the goal was met. Failure to reach a goal resulted in a reset of the monetary incentive value to $0.25. Ten out of 12 participants from the deposit group were determined to be responders to intervention, whereas 8 out of 13 participants from the no-deposit group were determined to be responders to intervention. Overall, there were no significant differences between the groups' step counts. However, the deposit group's intervention was cheaper to implement, which suggests that deposit contracts are a viable modification for physical activity interventions.

Using an intervention package with percentile schedules to increase on‐task behavior

AbstractImproving on‐task behavior can allow individuals to access more learning opportunities and is especially relevant for individuals with developmental disabilities. The current study examined the efficacy of an intervention package that used percentile schedule of reinforcement, feedback, and application of lower limits to changes in criteria to increase on‐task behaviors in children with developmental disabilities. Using a nonconcurrent multiple baseline across participants design, data revealed a functional relationship between the implementation of the intervention and an increase in the percentage of intervals that participants were on task. Overall, the participants' on‐task behavior improved from a mean of 32% during baseline to 68% during intervention, with a proportionate percentage change of 118%. Although there is no widely accepted method for shaping, using percentile schedules as part of an intervention package appears to be a promising way to shape behavior.

Региональная центильная таблица массы тела новорожденного для г. Киева и Киевской области

The objective: to develop a regional gestational percentiles table of body weight for newborns in Kiev and Kyiv’s oblast. Materials and methods. Data of the body weight of newborns were collected from Kyiv City Perinatal Center from January 2016 by January 2017. The total number included 5244 live births in the period of gestation 40+0–40+6 weeks of gestation. The standard deviation of the body weight, expressed as the percentage of the average body weight of all newborns, as well as the percentil calculator developed by Hadlock et al, supported by the WHO (2008), was used to generate the percentages and curves of the body weight. Materials and methods. A newborn body weight percentile table was constructed, depending on the gestational age. Differences were observed between the current average body weight of newborns for Kyiv and current WHO links. Conclusion. We found a rise in the average body weight of newborns, which we associate with excessive, unbalanced diet and the prescribing of a complex of multivitamins and biologically active substances during pregnancy. This indicates the importance of using this table for differential diagnosis of normal fetal growth from intrauterine growth restriction and small for fetal gestational age within the region of Kyiv and oblast. Key words: delayed fetal growth, percentile table of the city of Kiev, average body weight of newborns, percentile schedule.

Prevention of the development of problem behavior: A laboratory model.

Few studies have isolated the preventive efficacy of common behavioral strategies like noncontingent reinforcement (NCR) and differential reinforcement of alternative behavior (DRA). The purpose of the current study was to develop and evaluate a laboratory model of these two problem behavior prevention strategies. Undergraduate students participated in a computer simulation, in which clicks to a designated area of the computer screen were analogous to the emergence of problem behavior. The responding of participants in a control group, who experienced a percentile schedule used to mimic the shaping of problem behavior, was compared to that of participants in two experimental groups, each with a history of either DRA or NCR. Between-subjects group comparisons showed that both intervention strategies were equally effective in the prevention of our analog to problem behavior when compared to the control group. The strengths and limitations of a laboratory model for prevention are discussed in light of recent applied work in this area.

A bout analysis reveals age-related methylmercury neurotoxicity and nimodipine neuroprotection

Age-related deficits in motor and cognitive functioning may be driven by perturbations in calcium (Ca2+) homeostasis in nerve terminals, mechanisms that are also thought to mediate the neurotoxicity of methylmercury (MeHg). Calcium-channel blockers (CCBs) protect against MeHg toxicity in adult mice, but little is known about their efficacy in other age groups. Two age groups of BALB/c mice were exposed to 0 or 1.2mg/kg/day MeHg and 0 or 20mg/kg/day of the CCB nimodipine for approximately 8.5 months. Adults began exposure on postnatal day (PND) 72 and the retired breeders on PND 296. High-rate operant behavior was maintained under a percentile schedule, which helped to decouple response rate from reinforcer rate. Responding was analyzed using a log-survivor bout analysis approach that partitioned behavior into high-rate bouts separated by pauses. MeHg-induced mortality did not depend on age but nimodipine neuroprotection was age-dependent, with poorer protection occurring in older mice. Within-bout response rate (a marker of sensorimotor function) was more sensitive to MeHg toxicity than bout-initiation rate (a marker of motivation). Within-bout rate declined almost 2 months prior to overt signs of toxicity for the MeHg-only retired breeders but not adults, suggesting greater delay to toxicity in younger animals. Motor-based decrements also appeared in relatively healthy adult MeHg+NIM animals. Aging appeared to alter the processes underlying Ca2+ homeostasis thereby diminishing protection by nimodipine, even in mice that have not reached senescence. The study of MeHg exposure presents an experimental model by which to study potential mechanisms of aging.

Using Percentile Schedules to Increase Academic Fluency

After a learner becomes accurate with a task, fluency must be shaped over time to reach the target goal. However, shaping criteria can be somewhat arbitrary; thus, an objective criteria has the potential to improve implementation consistency. One such method is through the use of percentile schedules. The purpose of the current study was to use a percentile schedule as a means of determining the reinforcement criterion to improve the fluency for three academic tasks. The participant was a 14‐year‐old boy diagnosed with developmental disabilities. The use of the percentile schedule based reinforcement criterion resulted in increased fluency with two of the three academic tasks. This study suggests that percentile schedules may provide an objective criterion for improving fluency. Copyright © 2016 John Wiley & Sons, Ltd.

Effects of a Percentile Schedule for Vegetables on Increasing the Variety of Vegetables Consumed

Effects of a Percentile Schedule for Vegetables on Increasing the Variety of Vegetables Consumed

Response inhibition is impaired by developmental methylmercury exposure: Acquisition of low-rate lever-pressing

Developmental methylmercury (MeHg) exposure produces response perseveration on discrimination reversal procedures, disrupts sensitivity to reinforcement, and enhances sensitivity to dopamine agonists – a profile suggesting a deficit in behavioral inhibition. To examine inhibition, we examined MeHg's effects on the acquisition and persistence of low-rate lever-pressing following a history of high-rate responding. Additionally, we examined whether chronic exposure to selenium protects against MeHg's developmental neurotoxicity. Female rats were exposed in utero via maternal exposure to drinking water containing 0ppm, 0.5ppm or 5ppm of Hg as MeHg, producing approximately 0μg/kg/day, 40μg/kg/day, or 400μg/kg/day of Hg. The mothers (during gestation) and the offspring (throughout life) consumed a purified diet containing 0.06ppm or 0.6ppm of Se (as sodium selenite), forming a 2 (lifespan diet)×3 (developmental MeHg) factorial design. Adult offspring lever-pressed under two schedules of reinforcement. A differential reinforcement of high-rate (DRH) schedule imposed rigid response requirements that remained constant through the study. A high-rate percentile schedule (PCNT-H) incorporated a flexible criterion that reinforced short interresponse times using an adjusting criterion that was sensitive to recent performance. After high-rate responding stabilized, the PCNT-H schedule was abruptly inverted by reinforcing long interresponse times. Acquisition of low-rate responding was impaired in the MeHg-exposed rats because of intrusions of high-rate response bursts. DRH response rates did not change. Dietary selenium did not influence MeHg's effects. High-rate operant behavior perseverated, suggesting that gestational MeHg exposure impairs response inhibition – an effect that extends results previously reported using choice procedures or spatial and visual discrimination reversals.

SELEÇÃO DIRECIONAL DE NUMEROSIDADE: UM ESTUDO EXPLORATÓRIO

O presente estudo analisa a diferenciação numérica de padrões de resposta. Em uma caixa de Skinner com duas teclas, sete pombos receberam comida após bicarem pelo menos N vezes na tecla esquerda e depois uma vez na tecla direita (programa “Fixed Consecutive Number” de Mechner). Em cada ensaio, o parâmetro N era ajustado por um programa de reforço percentil (uma forma de shaping automático). O estudo teve dois objetivos. Primeiro, determinar como é que varia o tamanho das corridas na tecla da esquerda durante o procedimento de modelagem (shaping) e durante uma fase de extinção que se seguiu. Segundo, comparar os dados obtidos com as previsões de um modelo teórico de diferenciação da resposta. Os resultados mostraram que, durante a modelagem, o tamanho das corridas na tecla esquerda aumentou e depois, para alguns pombos, estabilizou, enquanto para outros pombos permaneceu variável. Alguns pombos pararam de responder quando o tamanho médio da corrida atingiu valores elevados. Observaram-se ainda variações sistemáticas nos tamanhos das corridas no interior de cada sessão como, por exemplo, o aumento do tamanho da corrida ao longo da sessão. Durante a fase de extinção os pombos produziram distribuições de tamanhos de corrida semelhantes às distribuições produzidas durante as últimas sessões de modelagem com exceção, em alguns sujeitos, do elevado número de corridas de tamanho zero. Estes resultados são interpretados à luz do modelo teórico de diferenciação numérica das respostas. Palavras-chave: Modelo matemático, numerosidade, esquema percentil, modelagem, pombo

SHAPING ACADEMIC TASK ENGAGEMENT WITH PERCENTILE SCHEDULES

The purpose of this study was to examine the use of percentile schedules as a method of quantifying the shaping procedure in an educational setting. We compared duration of task engagement during baseline measurements for 4 students to duration of task engagement during a percentile schedule. As a secondary purpose, we examined the influence on shaping of manipulations of the number of observations used to determine the criterion for reinforcement (the m parameter of the percentile formula). Results showed that the percentile formula was most effective when a relatively large m value (20 observations) was used.

Effects of advanced candidate anticonvulsants under two rodent models of 'counting'.

The behavioral effects of a variety of advanced candidate anticonvulsants for organophosphate-induced seizures were evaluated under two rodent 'counting' models. Rats pressed the left of two levers a number of times (a 'run') before pressing the right lever. The targeted performance was a run of 12. The training contingency was a targeted percentile schedule, which provided food if the current run was closer to 12 than two-thirds of the most recent runs. Baseline performance was well controlled by the target, with mean run lengths slightly less than 12. Once this performance was acquired, half the subjects were switched to a procedure providing food following runs of different lengths with a probability yoked to previous percentile schedule performance. The two procedures generate comparable baseline performances, but behavioral disruptions generate reinforcement loss only under the yoked procedure. Atropine, scopolamine, azaprophen, aprophen, trihexyphenidyl, procyclidine, benactyzine, biperiden and diazepam were tested. All produced dose-related decreases in overall run length and response rate. Responding was disrupted more readily under the yoked procedure than under the percentile procedure. Only atropine affected responding at doses below those effective against soman-induced seizures. Of the present candidates, trihexyphenidyl, procyclidine, benactyzine and biperiden appear most promising for further development.

Behavioral effects of enantiomers of dizocilpine under two “counting” procedures in rats

Stereoisomers of the N- methyl- D-aspartate antagonist dizocilpine (MK-801) were studied to determine whhether behavioral effects on complex operants depend on reinforcement loss accompanying behavioral disruption. Rats earned food pellets if the run of consecutive left-lever presses preceding a trial-terminating right-lever press approximated a target of 12. A percentile schedule reinforced any run closer to the target than two-thirds of the runs on the most recent 24 trials. Once the sequence was learned, half the subjects were shifted to a procedure that yoked reinforcement for each length run to the probability that length generated pellets during asymptotic percentile performance. Although these two procedures generate similar control run and reinforcement distributions disrupting behavior reduced reinforcement probability far more under the yoked than the percentile procedure. Despite this difference in drug-induced reinforcement loss, both enantiomers produced similar dose-related decreases in run length and responce rate under both procedures, with the (−) isomer approximatelely one log unit less potent tha the (+) isomer. The absence of differential effects under these procedures diminishes the likelihood that reinforcement loss contributes to dizocilpine's effects, indirectly bolstering claims that dizocilpine directly affects learning.

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.

Reinforcement loss and behavioral tolerance to d-amphetamine

Two procedures were used to examine the impact of reinforcement loss on the development of behavioral tolerance to the effects of d-amphetamine on control over response number in rats. Under both procedures, trials consisted of at least one left-lever press followed by a single right-lever press. Consecutive left-lever presses on each trial comprised a "run". A targeted percentile schedule provided reinforcement if the current run length was closer to the target length (12) than two-thirds of the most recent 24 runs. This procedure differentially reinforced runs around 12 while holding reinforcement probability constant at 0.333. A second group acquired the differentiation under the percentile schedule, but was then shifted to a procedure which yoked reinforcement probability by subject and run length to that obtained under asymptotic percentile schedule performance. The two procedures generated roughly comparable, but not identical, control run lengths, response rates, reinforcement probabilities and reinforcement rates. Only under the yoked procedure, however, did drug-induced disruptions in run length produce decreases in reinforcement density. Acute administration of amphetamine produced dose-related decreases in run length and overall response rate under both procedures. Daily pre-session administration of 1.7mg/kg amphetamine persistently suppressed run length under the percentile procedure, but not under the yoked procedure. Run lengths under the latter gradually increased with repeated amphetamine to a level equal to or slightly below baseline levels. Response rate was suppressed initially, and tolerance developed inconsistently to this effect in both groups. Dose-effect curves obtained when doses of amphetamine were substituted for the chronic dose showed a larger shift to the right with the yoked than percentile group for run length, and a similar but smaller effect for overall response rate. These results indicate that reinforcement loss substantially contributes to the development of tolerance to the behavioral effects of amphetamine, even when the comparison behaviors are generated by reinforcement contingencies that under non-drug conditions control very similar rates and patterns of behavior and reinforcement. Future comparison of acute and chronic drug effects on behaviors maintained by the percentile and yoked procedures may prove very helpful in illuminating drug-behavior interactions and the dynamic interrelations typically engendered by more traditional reinforcement schedules.

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.