Comparison of stimulus control and reinforcement control effects on imitative behavior

An attempt was made to evaluate reinforcement and stimulus control of imitative and non-imitative behavior. The imitative response required the subject to duplicate the experimenter's response by matching blocks that varied in color. The factor designed to evaluate stimulus control was fading, a procedure that systematically varies the differences between the imitative and non-imitative stimuli. The topography and duration of the non-imitative stimuli were faded in. The factors designed to evaluate reinforcement control were differential reinforcement of non-imitative behavior and time out from positive reinforcement. The results showed stimulus control of non-imitation to be more important than reinforcement control, and that reinforcing events were not sufficient to control non-imitation; while the arrangement of stimulus events was sufficient to control non-imitation. These results were related to studies providing evidence for the processes of discrimination and generalization.     

Control rate of response or reinforcement and amphetamine's effect on behavior.

The roles of control response rate and reinforcement frequency in producing amphetamine's effect on operant behavior were evaluated independently in rats. Two multiple schedules were arranged in which one variable, either response rate or reinforcement frequency, was held constant and the other variable manipulated. A multiple differential-reinforcement-of-low-rate seven-second yoked variable-interval schedule was used to equate reinforcement frequencies at different control response rates between multiple-schedule components. Amphetamine increased responding under the variable-interval component. In contrast, amphetamine decreased responding equivalently between components of a multiple random-ratio schedule that produced similar control response rates at different reinforcement frequencies. The results provide experimental support to the rate-dependency principle that control rate of responding is an important determinant of amphetamine's effect on operant behavior.     

Manipulating parameters of reinforcement to reduce problem behavior without extinction

Differential reinforcement of alternative behavior (DRA) most often includes extinction as a treatment component. However, extinction is not always feasible and it can be counter‐therapeutic if implemented without optimal treatment integrity. Researchers have successfully implemented DRA without extinction by manipulating various parameters of reinforcement such that alternative behavior is favored. We extended previous research by assessing three participants' sensitivities to quality, magnitude, and immediacy using arbitrary responses and reinforcers that maintain problem behavior. The results were used to implement an intervention for problem behavior using DRA without extinction. Our findings indicate that arbitrary responses can be used to identify individual and relative sensitivity to parameters of reinforcement for reinforcers that maintain problem behavior. Treatment was effective for all participants when we manipulated parameters of reinforcement to which they were most sensitive, and, for two participants, the treatment was less effective when we manipulated parameters to which they were least sensitive.     

Probability of reinforcement and the development of stimulus control

Pigeons were trained with a successive discrimination procedure in which responding during the negative stimulus was never reinforced and responding during the positive stimulus was reinforced according to one of four probability values. This discrimination training followed extensive training with a single, neutral stimulus and the same temporal distribution of reinforcements. The development of stimulus control was studied by tracing the difference in rate of responding between the positive and negative stimuli over the course of discrimination training. Response rate during the positive stimulus remained constant, while that during the negative stimulus decreased to zero. The probability of reinforcement associated with the positive stimulus affected both the total number of responses emitted during the negative stimulus and the number of negative stimulus presentations during which responding occurred. However, the number of reinforcements during the positive stimulus preceding the attainment of various degrees of stimulus control was similar for all probability values.     

Factors influencing inhibitory stimulus control: differential reinforcement of other behavior during discrimination training

Pigeons were trained to respond on a multiple variable-interval 1-min variable-interval 1-min schedule, then switched to a multiple variable-interval 1-min differential-reinforcement-of-other-behavior discrimination training. The rate of reinforcement was held constant during the shift from non-differential reinforcement to discrimination training. Behavioral contrast and post-discrimination inhibitory stimulus control followed the observation of a reduction in the rate of responding to the stimulus correlated with reinforcement for the non-occurrence of pecking.     

A comparison of fixed momentary differential reinforcement of other behavior to variable momentary differential reinforcement of other behavior to reduce challenging behavior

Differential reinforcement of other behavior (DRO) is commonly used to reduce behavioral excesses. Momentary DRO schedules involve delivery of reinforcement contingent upon the absence of the target behavior at a given moment. Two variations of momentary DRO exist: fixed-momentary (FM) DRO and variable-momentary (VM) DRO. In the current study, we directly compared FM-DRO and VM-DRO schedules to reduce challenging behavior maintained by automatic reinforcement exhibited by four children with autism spectrum disorder. The results suggest that both the DRO schedules were equally effective to reduce challenging behavior. A social validity measure showed that most caregivers rated the VM-DRO as a preferred schedule and noted the potential for FM-DRO schedule to become more discriminable over time, which could reduce its effectiveness. However, most caregivers also commented that the FM-DRO schedule was easier to implement.     

Inhibitory stimulus control and the magnitude of delayed reinforcement

The key pecking of pigeons was reinforced according to a variable-interval 1-min schedule during each of two successively presented stimuli. When the key was illuminated by a black line on a white background, reinforcement was delayed for 10 sec. When the key was illuminated by a plain white light, reinforcement was not delayed. For half of the subjects, the delayed reinforcer was 4.0-sec access to mixed grain, and for the remaining subjects it was 1.5-sec access. The immediate reinforcer was 1.5-sec access for all subjects. All subjects responded at a lower rate during the presentation of the black line; no between-group difference in terms of terminal response rate during the presentation of the line was found. However, subjects that received 4.0 sec of delayed reinforcement responded at a lower terminal rate during presentation of the plain white light than subjects that received 1.5 sec of delayed reinforcement. A subsequent generalization test along the line-orientation dimension produced flatter U-shaped gradients for subjects that received 4.0-sec of delayed reinforcement.     

The establishment of stimulus control by instructions and by differential reinforcement

A repeated acquisition design was used to study the effects of instructions and differential reinforcement on the performance of complex chains by undergraduates. The chains required responding on a series of keys that corresponded to characters that appeared on a monitor. Each day, subjects performed a new chain in a learning session and later relearned the same chain in a test session. Experiment 1 replicated previous research by showing that instructional stimuli paired with the correct responses in the learning sessions, combined with differential reinforcement in both learning and test sessions, resulted in stimulus control by the characters in each link. Experiment 2 separated the effects of instructional stimuli and differential reinforcement, and showed that stimulus control by the characters could be established solely by differential reinforcement during the test sessions. Experiment 3 showed that when a rule specified the relation between learning and test sessions, some subjects performed accurately in the test sessions without exposure to any differential consequences. This rule apparently altered the stimulus control properties of the characters much as did differential reinforcement during testing. However, compared to differential reinforcement, the rule established stimulus control more quickly.     

Antecedent reinforcement contingencies in the stimulus control of an auditory discrimination

In order to assess possible confounding of discriminative stimulus effects with those produced by the reinforcing stimulus, three groups of four rats each were trained for 45 hr on a variable-interval 1-min reinforcement program. Two groups were run on a multiple variable-interval extinction schedule in which the reinforcement stimulus (S^D) and the nonreinforcement stimulus (S^Δ) were two intensities of a 4-kHz (cps) tone separated by 40 or 10 db. The third group was run on a mixed schedule with a single intensity constantly present. The mixed-schedule animals showed no discrimination of the reinforcement program. Under the multiple schedule, the highest S^Δ rates were obtained after S^D intervals, regardless of the reinforcement availability in the S^D interval. These local rate variations in S^Δ were small in proportion to those produced by the S^D versus S^Δ intensities.     

The roles of stimulus control and reinforcement frequency in modulating the behavioral effects of d-amphetamine in the rat.

The behavioral effects of d-amphetamine have been shown to be modulated by stimulus control, with less impairment of performance occurring when control is great. When the fixed-consecutive-number schedule is used (on which at least a specified consecutive number of responses must be made on one operandum before a single response on another will produce a reinforcer), response rate tends to be invariant but reinforcement frequency is not. This study asks whether the differences in reinforcement frequency that usually accompany changes in stimulus control could themselves be responsible for the performance differences. Two versions of the fixed-consecutive-number schedule of reinforcement were combined into a multiple schedule within which stimulus control was varied but differences in reinforcement frequency were minimized by omitting some reinforcer deliveries during the component that usually had the higher reinforcement frequency. In one component, a compound discriminative stimulus was added with the eighth consecutive response on the first lever; a single response on the second lever was then reinforced. In the other component, no such stimulus was presented. With no added stimulus, large decreases occurred in the number of runs satisfying the minimum requirement for reinforcement at doses of drug that produced only minimal changes when an added stimulus controlled behavior. Thus, increased stimulus control diminishes the behavioral changes produced by d-amphetamine even when the possible contribution by baseline reinforcement rate is minimized.     

The control of feeding behavior by an imprinted stimulus

Imprinted ducklings were trained to peck a pole using brief presentations of the imprinted stimulus as the response-contingent (reinforcing) event. Subjects were then permitted to spend extended periods with continuous access to food and the imprinted stimulus (via a pole peck). For other (control) subjects the experimental situation was restricted to either responding for the stimulus, or feeding in the absence of the stimulus. For subjects in the control conditions, both activities occurred in cyclic fashion. When, however, there was continuous opportunity to respond for the stimulus and food was available, the tendency to respond was related to the tendency to feed. Other experiments showed that independent presentations of the stimulus could initiate feeding in imprinted ducklings with no prior pairing of the stimulus with food and with no prior pole-peck training. The most consistent control over feeding, however, was exhibited by ducklings that were imprinted and also accustomed to periodic removals of the stimulus. It is concluded that in ducklings, imprinting procedures are sufficient to endow an arbitrary stimulus with the capacity to release feeding behavior.     

The effect of vicarious reinforcement on attentive behavior in the classroom

The effect of social reinforcement delivered to target subjects on the attentive behavior of adjacent peers was examined in a classroom setting. In a combined reversal and multiple baseline design, two pairs of mentally retarded children were sequentially exposed to three reinforcement phases. After baseline rates of attentive behavior were obtained, praise was delivered to the target subject in each subject pair for attentive behavior. After a reversal phase, praise was delivered contingently to target subjects for inattentive behavior. In a final phase, contingent praise for attentive behavior was reinstated for the target subjects. Throughout the study, nontarget subjects received no direct reinforcers. The results indicated a vicarious reinforcement effect. Reinforcing attentive behavior of target subjects increased this behavior in adjacent peers. However, reinforcing inattentive behavior of target subjects also increased the attentive behavior of adjacent peers. The effects obtained through vicarious reinforcement were considered to reflect the discriminative stimulus properties of reinforcement, which may serve as a cue for the performance of nonreinforced peers.     

Family-based obesity treatment, then and now: twenty-five years of pediatric obesity treatment.

OBJECTIVE: Family-based treatments for pediatric obesity were developed over 25 years ago. Over that time, youth have become more obese and the environment more obesiogenic, which may influence efficacy of pediatric weight control. Mixed-effects regression models were used to compare the efficacy of programs initiated 20 to 25 years ago to current programs through 24-month follow-up, as well as to reanalyze 10-year outcomes of previous research using contemporary measures and analytic strategies. MAIN OUTCOME MEASURES: z-BMI and percent overweight. RESULTS: Results showed significant reductions over time, with no differences in z-BMI change for older versus contemporary studies. Age was a predictor of z-BMI up to 24 months, with younger children showing larger change. Mixed-effects regression models replicated previous long-term effects of family-based interventions. Gender was a predictor of long-term z-BMI change, with girls benefiting more over time than did boys. CONCLUSION: The efficacy of the family-based behavioral approach to treating pediatric obesity replicates over a 25-year period. Challenges in evaluating treatment effects over time are discussed. Ideas for studying choice of treatments that vary in effect size and for strengthening family-based behavioral treatments are noted.     

The effect upon simple animal behavior of different frequencies of reinforcement, Part II: separate control of the reinforcement of different IRTs

Rats' responding was stabilized for over 35 days on 4-min variable-interval reinforcement. Reinforcements per hour for 4-sec wide classes of interresponse times were then separately controlled by adjusting those for each class to the variable-interval values that had just prevailed. This produced little or no change in interresponse times, indicating that the new procedure was substantially equivalent to a variable-interval schedule. The variable-interval schedule produced a high and stable conditional probability of interresponse times in the 0- to 4-sec class, associated with a peak in reinforcements per hour for this class. Reducing the reinforcements per hour for this class while raising that for another class (by 3.3 reinforcements per hour) significantly reduced the conditional probability of 0- to 4-sec interresponse times. Restoring the 3.3 reinforcements per hour to the 0- to 4-sec class significantly elevated the conditional probability of interresponse times in this class. Hence, it is concluded that the distribution of interresponse times produced by a subject during some variable-interval schedules is determined partly by the relative reinforcement of different interresponse times that the variable-interval schedule provided.Reprinted from Part II of the Final Report of Research under Contract DA-49-007-MD-408 with the Medical Research and Development Board, Office of the Surgeon General, Department of the Army, 31 December 1954. Edwin B. Newman, Responsible Investigator; Douglas Anger, Research Assistant and author of report. Experimental work done in the Psychological Laboratories of Harvard University.     

The effect of reinforcement differences on choice and response distribution during stimulus compounding

In Experiments I and II, rats were trained to respond on one lever during light and another during tone. The absence of tone and light controlled response cessation. In the multiple schedule of Experiment I, all reinforcements were received for responding in tone or light; in the chain schedule of Experiment II, all reinforcements were received in no tone + no light for not responding. Experiment I subjects, for which tone and light were associated with response and reinforcement increase, responded significantly more to tone-plus-light than to tone or light alone (additive summation). Experiment II subjects, for which tone and light were associated with response increase and reinforcement decrease, responded comparably to tone, light, and tone + light. Thus, additive summation was observed when stimulus-response and stimulus-reinforcer associations in tone and light were both positive, but not when they were conflicting. All subjects in both experiments responded predominantly on the light-correlated lever during tone + light, even when light intensity was reduced in testing. Furthermore, when a light was presented to a subject engaged in tone-associated responding, all subjects immediately switched the locus of responding to the light-correlated lever. No change in locus occurred when a tone was presented to a subject engaged in light-associated responding, irrespective of the stimulus-reinforcer association conditioned to tone. The light-lever preference in tone + light indicates that the heightened responding observed in Experiment I was not the summation of tone-associated behavior with light-associated behavior. Rather, it appears to be the result of a facilitation of one operant (light-associated responding) by the reinforcement-associated cue for the other.