NEGATIVE SIDE EFFECTS OF NONCONTINGENT REINFORCEMENT

Noncontingent reinforcement (NCR) has emerged as a treatment package for severe behavior problems. Although concerns about potential side effects (such as incidental reinforcement) have been raised, there have been few reported negative side effects in published studies to date. In this article, we report an NCR treatment evaluation for severe aggression that produced (a) an extinction burst and (b) incidental reinforcement. These side effects were evaluated by examining within-session response patterns and response distributions. As a solution, a brief omission contingency was added to the reinforcement schedule. The omission contingency resulted in decreased aggression rates.     

USE OF EXTINCTION AND REINFORCEMENT TO INCREASE FOOD CONSUMPTION AND REDUCE EXPULSION

Extinction and reinforcement contingencies were used to treat 2 children with feeding disorders. Positive reinforcement and avoidance extinction effectively increased food acceptance but also increased food expulsion. Reduced expulsion and increased swallowing were achieved by repeated presentation of expelled food, a second extinction component.     

Learning about food: starlings, skinner boxes, and earthworms

Despite its importance as a tool for understanding a wide range of animal behavior, the study of reinforcement schedules in the laboratory has suffered from difficulties in the biological interpretation of its findings. This study is an operant-laboratory investigation of the ability of European starlings, Sturnus vulgaris, to learn to respond adaptively to the problem of foraging on patchily distributed prey that are uncertainly located in space. In order to maximize the biological relevance of the laboratory study, variation in the aggregation of earthworms, Lumbricus terrestris (a prey species), was rigorously quantified from the field, and the experimental birds were presented with reinforcement schedules designed to represent the extremes of the observed variation. The results demonstrate that, even for a single prey species, the degree to which individuals are aggregated can vary markedly over a range of spatial scales, and that starlings can rapidly learn to respond, in an adaptive manner, to these variations. These findings suggest that starlings are capable of adjusting their behavior to facilitate the efficient exploitation of prey that occurs in patches of an uncertain nature, and thus illustrate the heuristic value of an ecologically informed operant-laboratory approach to studying foraging behavior.     

Social fear and expressive reactions to social stimuli

This study explored whether subjects high as compared to low in social fear react with a more negative emotional response, measured as facial electromyographic (EMG) activity, when exposed to social stimuli (pictures of angry and happy facial expressions). It was found that subjects who rated themselves as relatively high in public speaking fear gave larger negative facial EMG responses (Corrugator supercilii muscle activity) to angry faces than did the low fear subjects. Low fear subjects, on the other hand, gave larger positive facial EMG responses (Zygomatic major muscle activity) to happy faces than did the high fear subjects. It was further found that happy stimuli were rated as more hostile and less friendly and happy by the high fear group. Consistent with earlier findings, it was concluded that the facial EMG technique is sensitive to detecting different reactions among subjects relatively high and low in social fear.     

Conjoint schedules of timeout deletion in pigeons.

This experiment attempted to bring behavior under joint control of two distinct contingencies, one that provided food and a second that extended the periods during which that food was available. Pigeons' responses on each of two keys were reinforced according to a single random-interval schedule of food presentation except during signaled timeout periods during which the schedule was temporarily disabled. By means of a conjoint schedule, responses on the initially less preferred key not only produced food but also canceled impending timeouts. When behavior came to predominate on this conjoint alternative, the consequences of responding on the two keys were reversed. Responding in 3 of 4 pigeons proved sensitive to the conjoint scheduled consequences, as evidenced by systematic shifts in response rates favoring the conjoint key. In 2 of these 3 pigeons, sensitivity to the conjoint contingency was evident under time-in:timeout ratios of 2:1 (time-in = 120 s, timeout = 60 s) and 1:5 (time-in = 30 s, timeout = 150 s), whereas for the other pigeon preference for the conjoint key was observed only under the latter sequence of conditions. There was only weak evidence of control by the conjoint scheduled consequences in the 4th subject, despite extended training and forced exposure to the conjoint alternative. The overall pattern of results is consistent with studies of timeout avoidance but also shares features in common with positively reinforced behavior.     

A COLLATERAL EFFECT OF REWARD PREDICTED BY MATCHING THEORY

Matching theory describes a process by which organisms distribute their behavior between two or more concurrent schedules of reinforcement (Herrnstein, 1961). In an attempt to determine the generality of matching theory to applied settings, 2 students receiving special education were provided with academic response alternatives. Using a combined simultaneous treatments design and reversal design, unequal ratio schedules of reinforcement were varied across two academic responses. Findings indicated that both subjects allocated higher rates of responses to the richer schedule of reinforcement, although only one responded exclusively to the richer schedule. The present results lend support to a postulation that positive reinforcement may have undesirable collateral effects that are predicted by matching theory (Balsam & Bondy, 1983).     

Delay and number of food reinforcers: Effects on choice and latencies

Pigeons were given a choice between two identical-duration situations (terminal links of chain schedules). One terminal link of the choice pair provided two food deliveries, and the other provided five. The exact times of these food deliveries differed between the terminal links and were varied over conditions. A single response during the initial link gave immediate access to the corresponding terminal link. Forced trials, during which only one of the initial-link keys was lighted, were interspersed with choice trials during which both initial-link keys were lighted. Choice tended to favor whichever terminal link was correlated with the higher sum of the immediacies (i.e., the sum of the reciprocals of the delays to each of the reinforcers following the choice, with all delays measured from the choice). Latencies on forced trials and on choice trials also were related (negatively) to the sum of the immediacies. This correlation among response measures (choice and latencies) suggests that both measures are manifestations of the effect of conditioned reinforcement on response tendencies.     

The effect of prompting and reinforcement of activity in elderly demented inpatients

On a ward for 24 psychogeriatric patients, 18 were randomly assigned to three groups with different experimental conditions. The first group was prompted and reinforced for different activities; the second was only prompted; and the third served as a control group. Activities, both the trained ones and others, were continuously monitored throughout the five week study. The results showed a clear increase in the trained activities after training. The prompting condition was effective, and the addition of reinforcement did not add any to the effects. There was no generalization to untrained activities, and the effects did not last at the 1 hr or 21 hr assessments, but was clearly visible at 5 min after training. Time seemed to be more important than place, i.e. the effect ceased with elapsed time, not because of changes in the situation.     

Quantification of rats' behavior during reinforcement periods

What is treated as a single unit of reinforcement often involves what could be called a reinforcement period during which two or more acts of ingestion may occur, and each of these may have associated with it a series of responses, some reflexive, some learned, that lead up to ingestion. Food-tray presentation to a pigeon is an example of such a “reinforcement period.” In order to quantify this behavior, a continuous-reinforcement schedule was used as the reinforcement period and was chained to a fixed-ratio schedule. Both fixed-ratio size and reinforcement-period duration were manipulated. Rats were used as subjects, food as reinforcement, and a lever press as the operant. Major findings included (a) a rapid decline in response rates during the first 15 to 20 seconds of the reinforcement periods, and (b) a strong positive relationship between these response rates and the size of the fixed ratio. Also revealed was a short scallop not normally found in fixed-ratio response patterns, whose length was a function of fixed-ratio size and reinforcement-period duration. It is suggested that rapidly fluctuating excitatory processes can account for many of these findings and that such processes are functionally significant in terms of behavioral compensation.     

Some antecedents of work-nonwork conflict

This study examined the relationships of three aspects of work schedules—shiftwork, length of workday, and work during weekends and holidays—with the perceived interrole conflict between work and nonwork. Personal background variables and characteristics of the work role itself were hypothesized to be directly related to the level of conflict and, in addition, to moderate the work schedules-conflict relationships. Subjects were 286 hotel employees. As expected all three aspects of work schedules were related to the level of felt work-nonwork conflict. Personal background variables were not related in any way to the level of conflict. Job satisfaction and organizational role conflict were found to be directly related to the level of interrole conflict and, in addition, to moderate the work schedules-conflict relationships. Together, job-related variables and the interactions among them accounted for over 50% of the variance in work-nonwork conflict.