The role of signals in two variations of differential‐reinforcement‐of‐low‐rate procedures

Differential‐reinforcement‐of‐low‐rate (DRL) schedules are used to decrease the overall rate of, but not eliminate, a target response. Two variations of DRL, spaced‐responding and full‐session, exist. Preliminary comparative analyses suggest that the two schedules function differently when unsignaled. We compared response rates under these two DRL variations with and without signals. In Experiment 1, five preschool students played a game in which points were earned under DRL schedules. In some sessions, a stimulus signaled when responses would be reinforced (S+) or not reinforced (S‐). In others, only an S‐ was present. Signals (S+/S‐) facilitated and maintained responding in both types of DRL schedules. In Experiment 2, we modified the signals with five different preschoolers. Instead of an S‐ only, we did not present any signals. Elimination and high variability of the target response were observed with the S‐ only and absence of S+/S‐, respectively. Signaled DRL schedules are recommended for application.     

CORRESPONDENCE BETWEEN SINGLE VERSUS DAILY PREFERENCE ASSESSMENT OUTCOMES AND REINFORCER EFFICACY UNDER PROGRESSIVE‐RATIO SCHEDULES

Research has suggested that a daily multiple‐stimulus‐without‐replacement (MSWO) preference assessment may be more sensitive to changes in preference than other assessment formats, thereby resulting in greater correspondence with reinforcer efficacy over time ( DeLeon et al., 2001 ). However, most prior studies have measured reinforcer efficacy using rate of responding under single‐operant arrangements and dense schedules or under concurrent‐operants arrangements. An alternative measure of reinforcer efficacy involves the evaluation of responding under progressive‐ratio (PR) schedules. In the present study, 7 participants were given a single paired‐stimulus (PS) preference assessment followed by daily MSWO preference assessments. After each daily MSWO, participants responded for each stimulus on a PR schedule. The correspondence between break points and preferences, as assessed by the 2 assessment formats, was examined. Results demonstrated that both preference assessments did equally well at predicting reinforcer efficacy, although the PS more consistently identified the most effective reinforcer.     

Decreasing Excessive Bids for Attention in a Simulated Early Education Classroom

Differential-reinforcement-of-low-rate (DRL) schedules can be used to decrease, but not eliminate, excessive bids for teacher attention in a classroom. There are two primary methods of implementing a DRL: full session and spaced responding. Some research suggests that the full-session DRL may eliminate target responding. The purpose of the current study was to compare the effectiveness of and preference for the two DRL methods in a simulated preschool classroom. Three participants completed difficult puzzles in baseline, both DRL, and differential-reinforcement-of-other-behavior (DRO) conditions. In the spaced-responding and full-session DRL conditions, the optimal rate of bids for attention was approximately 75% (two participants) or 50% (one participant) of baseline responding. All participants requested attention near the optimal criterion in both DRL conditions and at a lower rate (near zero) in the DRO condition. Treatment preference of the students was assessed in a concurrent-chain arrangement. All participants preferred both types of DRL conditions to DRO, and two participants showed a preference for the full-session DRL. Results suggest that either DRL procedure may be suitable for a preschool classroom, but a full-session DRL may be ideal.     

Response suppression on DRL by rats with septal damage

The effectiveness of the differential reinforcement for low rates of responding (DRL) contingency in suppressing response rates of septal rats was investigated by using a Multi-DRL-yoked-VI (variable interval) schedule of reinforcement. The yoking procedure equated the interreinforcement times on the two schedules. Each schedule was in effect for half of each session, and the change in schedule was signaled by the presence or absence of a cue light. Schedule order and DRL delay requirement were varied. For both normal and septal rats, the response rates were higher in the VI component than the DRL component; this effect demonstrates that the responding of septals as well as normals is suppressed by the differential reinforcement of a particular class of IRTs. A sharp difference in the level of responding occurred at the point of transition from one component of the multiple schedule to the other, which provides evidence of a discrimination between the two schedules for both normals and septals. The conclusion is that the responding of septals is suppressed by the DRL contingency and not controlled solely by the density and distribution of reinforcement.     

An extension of commonly used toilet-training procedures to children with autism spectrum disorder

The current study evaluated a toilet-training treatment package described by Greer et al. (2016) with children diagnosed with autism spectrum disorder (ASD). Most of the current research on toilet-training interventions for children with ASD are replications and modifications of Azrin and Foxx (1971) or (more recently) LeBlanc et al. (2005). However, these procedures are composed of components that are not included in studies with typically developing (TD) children. For example, Greer et al. evaluated the effectiveness of three typical components within a toilet-training package, mostly with TD participants: a 30-min sit schedule, placing participants in underwear, and differential reinforcement. The primary purpose of the current study was to replicate and extend the treatment package described by Greer et al. to children with ASD. A secondary purpose was to evaluate modifications necessary for individualized toilet training when the commonly used components were ineffective. The results of Greer et al. were replicated for 11 participants with ASD in the current study, suggesting that intensive toileting interventions (e.g., interventions requiring overcorrection, reprimands, and dense sit schedules) may only be necessary for a subset of individuals with ASD.     

Controlling human fixed-interval performance

Both high and relatively constant rates of responding without post-reinforcement pauses and lower rates with pauses after reinforcement are produced by human subjects under fixed-interval (FI) schedules. Such FI rates and patterns may be controlled when subjects are provided with different histories of conditioning and different conditions of response cost (reinforcement penalties per response). Subjects with a conditioning history under ratio schedules typically produce high and relatively constant rates of responding under FI schedules; this responding does not change systematically with changes in FI value. In contrast, subjects with a history under schedules which produce little or no responding between reforcements [such as differential-reinforcement-of-low-rate (DRL) schedules] tend to pause after reinforcement and respond at low rates under FI schedules, whether or not they also have ratio conditioning histories; cost increases the likelihood of this type of performance. For DRL-history subjects, post-reinforcement pauses increase and response rates decrease as FI values increase.     

Effects of a brief novel stimulus during temporally spaced responding: Evidence for external inhibition?

Following training on schedules which differentially reinforce low rates of responding (DRL), three rats were exposed to a procedure to test for external inhibition. During test trials, a tone was presented midway in the DRL interval and the latency to the next response recorded. The incidence of external inhibition (defined in terms of the latency and its relative probability) appeared to be positively related to the size of the DRL schedule and not to measures of the subject’s “efficiency” on the schedule. An alternative view to the “pure” disinhibition hypothesis is presented which stresses the disruption of collateral behavior sequences which maintain responding under the DRL schedule.     

Chained and tandem scheduling with children

Children 4 to 7 yr in age were reinforced with trinkets and pennies on chained and tandem schedules. The schedules used were chain DRL FR, chain DRO FR, chain FI FR, tand FI FR, and tand DRO FR. Chain DRL FR and chain DRO FR schedules almost always produced strong schedule and stimulus control, but chain FI FR schedules rarely did if additional techniques were not used. Strong control was produced with chain FI FR schedules, however, if: (a) the FR component was increased in size; (b) schedule and stimulus control was first established with chain DRL FR or chain DRO FR schedules before shifting to the chain FI FR; or (c) an external clock was attached to the FI. Tand FI FR schedules never produced regular or repeatable patterns of responding when additional procedures were not used. Rate patterns resembling those of chain FI FR schedules were produced by tand FI FR schedules, however, if: (a) an external clock was attached to the FI component or (b) control was established by means of tand DRO FR schedules before the tand FI FR was used. Stimulus control was found to be exercised by specific visual stimuli, change of stimuli, and schedule order. Control exercised by schedule order was probably mediated by the child's own behavior which had assumed discriminative stimulus properties.     

AGGRESSION AS POSITIVE REINFORCEMENT IN MICE UNDER VARIOUS RATIO‐ AND TIME‐BASED REINFORCEMENT SCHEDULES

There is evidence suggesting aggression may be a positive reinforcer in many species. However, only a few studies have examined the characteristics of aggression as a positive reinforcer in mice. Four types of reinforcement schedules were examined in the current experiment using male Swiss CFW albino mice in a resident—intruder model of aggression as a positive reinforcer. A nose poke response on an operant conditioning panel was reinforced under fixed‐ratio (FR 8), fixed‐interval (FI 5‐min), progressive ratio (PR 2), or differential reinforcement of low rate behavior reinforcement schedules (DRL 40‐s and DRL 80‐s). In the FR conditions, nose pokes were maintained by aggression and extinguished when the aggression contingency was removed. There were long postreinforcement pauses followed by bursts of responses with short interresponse times (IRTs). In the FI conditions, nose pokes were maintained by aggression, occurred more frequently as the interval elapsed, and extinguished when the contingency was removed. In the PR conditions, nose pokes were maintained by aggression, postreinforcement pauses increased as the ratio requirement increased, and responding was extinguished when the aggression contingency was removed. In the DRL conditions, the nose poke rate decreased, while the proportional distributions of IRTs and postreinforcement pauses shifted toward longer durations as the DRL interval increased. However, most responses occurred before the minimum IRT interval elapsed, suggesting weak temporal control of behavior. Overall, the findings suggest aggression can be a positive reinforcer for nose poke responses in mice on ratio‐ and time‐based reinforcement schedules.     

Some properties of spaced responding in pigeons

Pigeons exposed to a schedule which reinforces interresponse times (IRTs) longer than a given value (DRL schedule) eventually reach a stable pattern of responding which is shown to be a function both of the DRL value and of previous experience with other DRL values. On any given DRL schedule, the stable performance of most pigeons which have been previously exposed to a variety of such schedules, shows an IRT distribution with median equal to the DRL value. For DRL values longer than about 30 sec, however, the median IRT falls short of the DRL value; this failure of adjustment to longer values appears to be a species characteristic of pigeons. The function relating reinforcement rate to 1/DRL value is also shown to be approximately linear over the same range, with variable slope (less than 45°) and a downturn in the vicinity of DRL 30.     

Using differential reinforcement of low rates to reduce children's requests for teacher attention

We evaluated the effectiveness of full-session differential reinforcement of low rates of behavior (DRL) on 3 primary school children's rates of requesting attention from their teacher. Using baseline rates of responding and teacher recommendations, we set a DRL schedule that was substantially lower than baseline yet still allowed the children access to teacher assistance. The DRL schedule was effective in reducing children's requests for assistance and approval, and the teacher found the intervention highly useful and acceptable. The possible mechanisms that account for behavior change using full-session DRL schedules are discussed.     

Conditioned suppression of drl responding: Effect of ucs intensity, schedule parameter, and schedule context

In Experiment I, groups of rats were trained to press a lever for food reinforcement on differential reinforcement of low rate (DRL) schedules which differed in parameter value. A stimulus which terminated with either a 0.5-mA or 2.0-mA electric shock was then superimposed upon each DRL baseline. In general, the magnitude of conditioned suppression was an inverse function of DRL schedule parameter and a direct function of shock intensity. Experiment II demonstrated that the rate of responding maintained by the DRL component of a multiple DRL-extinction schedule decreased during a stimulus preceding a 0.5-mA shock, whereas the rate of responding maintained by the DRL component of a multiple DRL-variable interval schedule showed little change or increased slightly during a stimulus preceding a 0.5-mA shock.     

Pigeons' performance under differential reinforcement of low rate schedules depends upon the operant

Pigeons were reinforced with grain for pecking a key or depressing a foot treadle according to differential reinforcement of low rate (DRL) schedules. Birds which depressed a treadle performed efficiently on DRL schedules as high as DRL 35-sec; while birds reinforced for keypecking showed low efficiency under DRL 14-sec. While treadle pressing and keypecking differ along a number of dimensions (including force requirement of the operant and differences in temporal distributions of responses), the present results are consistent with an interpretation based on differences in the degree to which these two responses are elicited by periodic presentations of food.     

Briefly delayed reinforcement: An interresponse time analysis

Key-peck responding of pigeons was compared under VI or DRL schedules arranging immediate reinforcement and briefly (.5 sec) delayed reinforcement. Delays were either signaled by a blackout in the chamber, unsignaled, or unsignaled with an additional requirement that responding not occur during the .5 sec interval immediately preceding reinforcement (response delay). Relative to the immediate reinforcement condition, response rates increased during the unsignaled delay, decreased during the signaled delay, and were inconsistent during the response delay condition. An analysis of interresponse times (IRTs) under the different conditions revealed a substantial increase in the frequency of short (0 to .5 sec) IRTs during the unsignaled condition and generally during the response delay conditions compared to that during the immediate reinforcement baseline. Signaled delays decreased the frequency of short (0 to .5 sec) IRTs relative to the immediate reinforcement condition. The results suggest that brief unsignaled delays and, in many instances, response delays increase the frequency of short IRTs by eliminating constraints on responding.     

Further investigation of increasing vocalizations of children with autism with a speech-generating device

We replicated and extended the findings of Gervarter et al. (2016) by using prompting and reinforcement to produce increased vocal speech with 3 young children diagnosed with autism spectrum disorder (ASD) who used a speech generating device (SGD). We extended Gervarter et al. by adopting a more robust experimental design, conducting session-by-session preference assessments, and measuring the emergence of novel vocalizations. The frequency of vocalizations increased for all 3 participants after the introduction of an echoic prompt. These results suggest that SGD-based interventions may lead to increased vocal output for children with ASD.     

A practical variation of a multiple-schedule procedure: brief schedule-correlated stimuli

Multiple schedules using continuous discriminative stimuli have been used to minimize children's disruptive requesting for teacher attention (e.g., colored floral leis; Tiger & Hanley, 2004; Tiger, Hanley, & Heal, 2006). The present study evaluated the effectiveness of, and children's preferences for, two multiple-schedule arrangements in which brief experimenter vocalizations served as discriminative stimuli. Results showed that brief signals were highly effective discriminative stimuli for 3 of the 4 children, and that all children preferred one or both variations of the multiple schedule to a control arrangement. For 1 child, highly discriminated responding was achieved only when continuous signals were introduced.     

Some determinants of remote behavioral history effects in humans

Undergraduates were exposed to a series of reinforcement schedules: first, to a fixed-ratio (FR) schedule in the presence of one stimulus and to a differential-reinforcement-of-low-rate (DRL) schedule in the presence of another (multiple FR DRL training), then to a fixed-interval (FI) schedule in the presence of a third stimulus (FI baseline), next to the FI schedule under the stimuli previously correlated with the FR and DRL schedules (multiple FI FI testing), and, finally, to a single session of the multiple FR DRL schedule again (multiple FR DRL testing). Response rates during the multiple FI FI schedule were higher under the former FR stimulus than under the former DRL stimulus. This effect of remote histories was prolonged when either the number of FI-baseline sessions was small or zero, or the time interval between the multiple FR DRL training and the multiple FI FI testing was short. Response rates under these two stimuli converged with continued exposure to the multiple FI FI schedule in most cases, but quickly differentiated when the schedule returned to the multiple FR DRL.     

Temporal regulation of children with autism spectrum disorder exposed to a differential-reinforcement-of low-rates schedule

This study investigated temporal adjustment of children with autism spectrum disorder under a differential-reinforcement-of-low-rates (DRL) schedule. Sixteen participants, aged 3.2 to 7 years, were exposed to two conditions, DRL 5 s and DRL 20 s. Children participated in 7 sessions in each condition, except for 1 participant who attained the adjustment criteria in the DRL 5-s schedule. Temporal adjustment was measured with the proportion of reinforced interresponse times (IRTs) and the mean IRT. The operant response was a press on a touch screen and the reinforcers were cartoons. IQ and receptive language were measured prior to the DRL sessions. Results showed that the mean proportion of reinforced IRTs was slightly higher in the DRL 5-s schedule. The mean IRT was above the IRT requirement in both conditions. However, substantial individual variability was observed. Children with higher IQ and receptive language scores presented a greater proportion of reinforced IRTs in both conditions. Moreover, participants who adjusted their responses to the DRL 5-s schedule were more likely to adjust responding to the DRL 20-s schedule. This suggests that some children might be more sensitive to reinforcement contingencies than others. This study points at future research in the field of timing in children.     

Failure to acquire an inhibitory task following seizure-induced brain damage

Male rats that had displayed limbic seizures following a single pair of systemic injections of lithium and pilocarpine were trained 2 months later on an operant schedule that required differential low rates of responding (DRL). The seizured rats never acquired schedules that required either 6-sec. or 12-sec. inhibition of responses following a reward; these rats displayed more perseverative responding and shorter interresponse times than controls. Histomorphology indicated severe brain damage primarily within the entorhinal cortices (and adjacent amygdala) and dorsal thalamus.     

Exchange schedules in token economies: A preliminary investigation of second‐order schedule effects

Basic research shows that token‐production and exchange‐production schedules in token economies affect each other as second‐order schedules (i.e., the exchange‐production schedule's requirements affect responding toward the token‐production schedule). This relationship has not been investigated with children in academic settings despite the widespread use of token economies in this context. This study compared the effects of fixed‐ratio (FR) and variable‐ratio (VR) exchange‐production schedules of equal ratios (2, 5, and 10) on responding toward an FR 1 token‐production schedule with a child diagnosed with autism. A concurrent chains assessment was also conducted to assess the participant's relative preference for FR and VR exchange‐production schedule arrangements within her typical discrete trial training. Results showed no difference in response rate between the two schedule types. However, the concurrent chains assessment revealed an exclusive preference for the VR arrangement.