Teacher report and direct assessment of preferences for identifying reinforcers for young children

Teachers were asked to identify and rank 10 preferred stimuli for 9 toddlers, and a hierarchy of preference for these items was determined via a direct preference assessment. The reinforcing efficacy of the most highly preferred items identified by each method was evaluated concurrently in a reinforcer assessment. The reinforcer assessment showed that all stimuli identified as highly preferred via the direct preference assessment and teacher rankings functioned as reinforcers. The highest ranked stimuli in the direct assessment were more reinforcing than the teachers' top-ranked stimuli for 5 of 9 participants, whereas the teachers' top-ranked stimulus was more reinforcing than the highest ranked stimulus of the direct assessment for only 1 child. A strong positive correlation between rankings generated through the two assessments was identified for only 1 of the 9 participants. Despite poor correspondence between rankings generated through the teacher interview and direct preference assessment, results of the reinforcer assessment suggest that both methods are effective in identifying reinforcers for toddlers.     

Age trends in stimulus overselectivity

Stimulus overselectivity refers to the phenomenon whereby stimulus control over behavior is exerted only by a limited subset of the total number of stimuli present during discrimination learning. It often is displayed by individuals with autistic spectrum disorders or learning disabilities, but is not exclusive to those groups. The present studies investigated the impact of aging on stimulus control and overselectivity. Three age groups--18-22, 47-55, and 70-80 year olds-were studied in two experiments. All participants were trained on a simple discrimination task, randomly assigned to one of two conditions (either with or without a distractor task), and then tested for the emergence of overselectivity (Experiment 1). In Experiment 2 responding controlled by the overselected stimulus elements was reduced by introducing a verbal punisher. In subsequent tests, control of behavior by the previously underselected elements from Experiment 1 was enhanced across the two younger age groups but not the oldest group of participants. The results are discussed in relation to the attention-deficit and overshadowing accounts of overselectivity.     

Tests of behavioral-economic assessments of relative reinforcer efficacy: economic substitutes

This experiment was conducted to test predictions of two behavioral-economic approaches to quantifying relative reinforcer efficacy. According to the first of these approaches, characteristics of averaged normalized demand curves may be used to predict progressive-ratio breakpoints and peak responding. The second approach, the demand analysis, rejects the concept of reinforcer efficacy, arguing instead that traditional measures of relative reinforcer efficacy (breakpoint, peak response rate, and choice) correspond to specific characteristics of non-normalized demand curves. The accuracy of these predictions was evaluated in rats' responding for food or fat: two reinforcers known to function as partial substitutes. Consistent with the first approach, predicted peak normalized response output values (Omax) obtained under single-schedule conditions ordinally predicted progressive-ratio breakpoints and peak responding. Predictions of the demand analysis had mixed success. Pmax and Omax were significantly correlated with PR breakpoints and peak responding (respectively) when fat, but not when food, was the reinforcer. Relative consumption of food and fat under single schedules of reinforcement did not predict preference better than chance. The normalized demand analysis is supplemented with the economic concept of diminishing marginal utility, to predict preference shifts across the range of food and fat prices examined.     

Examination of relative reinforcement effects of stimuli identified through pretreatment and daily brief preference assessments.

Several brief preference assessments have recently been developed to identify reinforcers for individuals with developmental disabilities. One purported advantage of brief assessments is that they can be administered frequently, thus accommodating shifts in preference and presumably enhancing reinforcement effects. In this study, we initially conducted lengthy paired‐choice preference assessments and identified a hierarchy of preferred items for 5 individuals with developmental disabilities. Subsequently, brief multiple‐stimulus‐without‐replacement assessments using the same items were completed each day prior to work sessions. On days when results of the daily brief assessment differed from the one‐time lengthy assessment, the relative reinforcing effects of the top items from each assessment were compared in a concurrent‐schedule arrangement. The results revealed that when the two assessments differed, participants generally allocated more responses to the task associated with the daily top‐ranked item.     

How do reinforcers affect choice? Preference pulses after responses and reinforcers

In concurrent schedules, reinforcers are often followed by a brief period of heightened preference for the just‐productive alternative. Such ‘preference pulses’ may reflect local effects of reinforcers on choice. However, similar pulses may occur after nonreinforced responses, suggesting that pulses after reinforcers are partly unrelated to reinforcer effects. McLean, Grace, Pitts, and Hughes (2014) recommended subtracting preference pulses after responses from preference pulses after reinforcers, to construct residual pulses that represent only reinforcer effects. Thus, a reanalysis of existing choice data is necessary to determine whether changes in choice after reinforcers in previous experiments were actually related to reinforcers. In the present paper, we reanalyzed data from choice experiments in which reinforcers served different functions. We compared local choice, mean visit length, and visit‐length distributions after reinforcers and after nonreinforced responses. Our reanalysis demonstrated the utility of McLean et al.'s preference‐pulse correction for determining the effects of reinforcers on choice. However, visit analyses revealed that residual pulses may not accurately represent reinforcer effects, and reinforcer effects were clearer in visit analyses than in local‐choice analyses. The best way to determine the effects of reinforcers on choice may be to conduct visit analyses in addition to local‐choice analyses.     

Stimuli previously associated with reinforcement mitigate resurgence

Resurgence refers to the recurrence of an extinguished target behavior following subsequent suspension of alternative reinforcement. Delivery of reinforcers during extinction of alternative behavior has been shown to mitigate resurgence. The present experiment aimed to determine whether delivering stimuli associated with reinforcers during resurgence testing similarly mitigates resurgence. Three groups of rats pressed target levers for food according to variable‐interval 15‐s schedules during Phase 1. In Phase 2, lever pressing was extinguished, and an alternative nose‐poke response produced alternative reinforcement according to a variable‐interval 15‐s schedule. Food reinforcement was always associated with illumination of the food aperture and an audible click from the pellet dispenser during Phases 1 and 2. Phase 3 treatments differed between groups. For one group, nose poking continued to produce food and food‐correlated stimuli. Both of these consequences were suspended for a second group. Finally, nose poking produced food‐correlated stimuli but not food for a third group. Target‐lever pressing resurged in the group that received no consequences and in the group that received only food‐correlated stimuli for nose poking. Resurgence, however, was smaller for the group that received food‐correlated stimuli than for the group that received no consequences for nose poking. Target‐lever pressing did not increase between phases in the group that continued to receive food and associated stimuli. Thus, delivery of stimuli associated with food reinforcement after suspension of food reduced but did not eliminate resurgence of extinguished lever pressing. These findings contribute to potential methodologies for preventing relapse of extinguished problem behavior in clinical settings.     

Disruption of responding maintained by conditioned reinforcement: alterations in response-conditioned-reinforcer relations

An observing procedure was used to investigate the effects of alterations in response-conditioned-reinforcer relations on observing. Pigeons responded to produce schedule-correlated stimuli paired with the availability of food or extinction. The contingency between observing responses and conditioned reinforcement was altered in three experiments. In Experiment 1, after a contingency was established in baseline between the observing response and conditioned reinforcement, it was removed and the schedule-correlated stimuli were presented independently of responding according to a variable-time schedule. The variable-time schedule was constructed such that the rate of stimulus presentations was yoked from baseline. The removal of the observing contingency reliably reduced rates of observing. In Experiment 2, resetting delays to conditioned reinforcement were imposed between observing responses and the schedule-correlated stimuli they produced. Delay values of 0, 0.5, 1, 5, and 10 s were examined. Rates of observing varied inversely as a function of delay value. In Experiment 3, signaled and unsignaled resetting delays between observing responses and schedule-correlated stimuli were compared. Baseline rates of observing were decreased less by signaled delays than by unsignaled delays. Disruptions in response-conditioned-reinforcer relations produce similar behavioral effects to those found with primary reinforcement.     

Effects of reinforcer consumption and magnitude on response rates during noncontingent reinforcement

Results of previous research on the effects of noncontingent reinforcement (NCR) have been inconsistent when magnitude of reinforcement was manipulated. We attempted to clarify the influence of NCR magnitude by including additional controls. In Study 1, we examined the effects of reinforcer consumption time by comparing the same magnitude of NCR when session time was and was not corrected to account for reinforcer consumption. Lower response rates were observed when session time was not corrected, indicating that reinforcer consumption can suppress response rates. In Study 2, we first selected varying reinforcer magnitudes (small, medium, and large) on the basis of corrected response rates observed during a contingent reinforcement condition and then compared the effects of these magnitudes during NCR. One participant exhibited lower response rates when large-magnitude reinforcers were delivered; the other ceased responding altogether even when small-magnitude reinforcers were delivered. We also compared the effects of the same NCR magnitude (medium) during 10-min and 30-min sessions. Lower response rates were observed during 30-min sessions, indicating that the number of reinforcers consumed across a session can have the same effect as the number consumed per reinforcer delivery. These findings indicate that, even when response rate is corrected to account for reinforcer consumption, larger magnitudes of NCR (defined on either a per-delivery or per-session basis) result in lower response rates than do smaller magnitudes.     

Response-restriction analysis: II. Alteration of activity preferences

We used response-restriction (RR) assessments to identify the preferences of 7 individuals with mental retardation for a variety of vocational and leisure activities. We subsequently increased their engagement in nonpreferred activities using several procedures: response restriction per se versus a Premack-type contingency (Study 1), supplemental reinforcement for engagement in target activities (Study 2), and noncontingent pairing of reinforcers with nonpreferred activities (Study 3). Results indicated that preferences are not immutable and can be altered through a variety of relatively benign interventions and that the results of RR assessments may be helpful in determining which types of procedures may be most effective on an individual basis.