IMPULSIVITY IN STUDENTS WITH SERIOUS EMOTIONAL DISTURBANCE: THE INTERACTIVE EFFECTS OF REINFORCER RATE,DELAY, AND QUALITY

We conducted two studies extending basic matching research on self-control and impulsivity to the investigation of choices of students diagnosed as seriously emotionally disturbed. In Study 1 we examined the interaction between unequal rates of reinforcement and equal versus unequal delays to reinforcer access on performance of concurrently available sets of math problems. The results of a reversal design showed that when delays to reinforcer access were the same for both response alternatives, the time allocated to each was approximately proportional to obtained reinforcement. When the delays to reinforcer access differed between the response alternatives, there was a bias toward the response alternative and schedule with the lower delays, suggesting impulsivity (i.e., immediate reinforcer access overrode the effects of rate of reinforcement). In Study 2 we examined the interactive effects of reinforcer rate, quality, and delay. Conditions involving delayed access to the high-quality reinforcers on the rich schedule (with immediate access to low-quality reinforcers earned on the lean schedule) were alternated with immediate access to low-quality reinforcers on the rich schedule (with delayed access to high-quality reinforcers on the lean schedule) using a reversal design. With 1 student, reinforcer quality overrode the effects of both reinforcer rate and delay to reinforcer access. The other student tended to respond exclusively to the alternative associated with immediate access to reinforcers. The studies demonstrate a methodology based on matching theory for determining influential dimensions of reinforcers governing individuals' choices.     

Discrete-trial choice in pigeons: Effects of reinforcer magnitude

The preference of pigeons for large reinforcers which occasionally followed a response versus small reinforcers which invariably followed a response was studied in a discrete-trial situation. Two differently colored keys were associated with the two reinforcement alternatives, and preference was measured as the proportion of choice trials on which the key associated with uncertain reinforcement was pecked. A combination of choice and guidance trials insured that received distributions of reinforcement equalled the scheduled distributions. For five of six subjects, preference for the uncertain reinforcer appeared to be a linear function of the magnitude of the certain reinforcer. In addition, there was greater preference for the response alternative associated with uncertain reinforcement than would be expected on the basis of net reinforcer value.     

EVALUATION OF A REINFORCEMENT PROCEDURE FOR ACCELERATING WORK RATE IN A SELF-PACED COURSE1

Students in a self-paced child development course were assigned to one of seven groups. One bonus point, which contributed toward the student's final grade, was given for each unit completed during a specified two-week period. In a combined baseline-reversal design, bonus points could be earned at different times for each group, and some groups had weeks without bonus points interspersed between bonus weeks. All seven groups and 78% of individual students completed units at a faster rate during bonus periods than during the balance of the semester. For the 58 students completing the course, mean units per week during bonus periods was 2.40 (SD = 1.60); for the balance of the semester mean units per week was 0.96 (SD = 0.37). Awarding bonus points for a limited period early in the term appears to be a useful procedure for increasing rates during this period in which rates are typically low. Although similar effects have been reported by others (e.g., Miller, Weaver, and Semb, Journal of Applied Behavior Analysis, 1974, 7 , 87–91), the advantage of the present procedure is that the increase in rate is accomplished by means of reinforcement for high rates rather than punishment (low grades or forced withdrawal) for low rates.     

Some conditions affecting the choice to cooperate or compete

Three experiments investigated conditions affecting the choice to cooperate or compete. Experiment I compared the effects first of an individual activity, then of a competitive task as an alternative to cooperation. For both comparisons, subjects could earn more by cooperating. Choice of competition, but not individual activity, was found to depend on the task choice contingencies. Competition predominated when both subjects could compete if either or both chose competition. Previously competitive pairs cooperated when both subjects could cooperate if either or both chose cooperation. Experiment II investigated the effects of differences in magnitude of the reinforcers for cooperating or competing. Choice between the two alternatives was manipulated in all pairs by varying reinforcer difference. Competition was chosen over cooperation only within the limits within which competition was potentially profitable. Experiment III replicated the findings of Experiment II using triads. Subjects in triads, however, were more likely to withdraw from the experiment. Thus, the data for pairs and triads suggest an orderly relation between reinforcer difference for cooperating or competing and task choice. Motivation of subjects to maximize relative gain by competing can be overridden by moderate reinforcer differences favoring cooperation.     

REPLICATION OF THE ACHIEVEMENT PLACE MODEL IN CALIFORNIA1

Attempting to replicate procedures from Achievement Place, token reinforcement procedures were used to modify savings, conversational interruptions, and table-setting of delinquent boys residing in a home-style, community based, treatment setting. The tokens (points) were redeemable for various privileges and could be earned for specified appropriate behaviors and lost for specified inappropriate behaviors. Contingent point fines reduced the frequency of interruptions. Point rewards improved table-setting, but even large point rewards did not substantially increase savings. Baseline data indicated that lateness to dinner was not a problem, as it was in Achievement Place. Withdrawal of contingent points and back-up rewards did not disrupt the clean-up behavior of two boys.     

AN ANALYSIS OF REINFORCER SUBSTITUTABILITY USING OBJECT MANIPULATION AND SELF-INJURY AS COMPETING RESPONSES

The concept of reinforcer substitutability proposes a continuum of interactions among reinforcers in a given situation. At one end of this continuum, reinforcers are substitutable, with one reinforcer being readily traded for another. We conducted an analysis of reinforcers that were substitutable with those produced by self-injurious behavior (SIB). Three individuals with profound developmental disabilities, whose SIB appeared to be maintained by automatic reinforcement, participated. Results of three experiments showed that (a) object manipulation and SIB were inversely related when leisure materials and SIB were concurrently available, with participants showing almost complete preference for object manipulation; (b) attempts to reduce SIB using the preferred objects as reinforcers in differential reinforcement contingencies were unsuccessful for all 3 participants; and (c) participants' preferences for SIB or object manipulation systematically changed when reinforcer cost (the amount of effort required to obtain the object) was varied. Results of the three experiments illustrate the importance of examining interactions among concurrently available reinforcers when conducting reinforcer assessments.     

Residence time in concurrent foraging with fixed times to prey arrival

Five pigeons were trained in a concurrent foraging procedure in which reinforcers were occasionally available after fixed times in two discriminated patches. In Part 1 of the experiment, the fixed times summed to 10 s, and were individually varied between 1 and 9 s over five conditions, with the probability of a reinforcer being delivered at the fixed times always .5. In Part 2, both fixed times were 5 s, and the probabilities of food delivery were varied over conditions, always summing to 1.0. In Parts 3 and 4, one fixed time was kept constant (Part 3, 3 s; Part 4, 7 s) while the other fixed time was varied from 1 s to 15 s. Median residence times in both patches increased with increases in the food-arrival times in either patch, but increased considerably more strongly in the patch in which the arrival time was increased. However, when arrival times were very different in the two patches, residence time in the longer arrival-time patch often decreased. Patch residence also increased with increasing probability of reinforcement, but again tended to fall when one probability was much larger than the other. A detailed analysis of residence times showed that these comprised two distributions, one around a shorter mode that remained constant with changes in arrival times, and one around a longer mode that monotonically increased with increasing arrival time. The frequency of shorter residence times appeared to be controlled by the probability of, and arrival time of, reinforcers in the alternative patch. The frequency of longer residence times was controlled directly by the arrival time of reinforcers in a patch, but not by the probability of reinforcers in a patch. The environmental variables that control both staying in a patch and exiting from a patch need to be understood in the study both of timing processes and of foraging.     

Determination of discount functions in rats with an adjusting-amount procedure.

An adjusting-amount procedure was used to measure discounting of reinforcer value by delay. Eight rats chose between a varying amount of immediate water and a fixed amount of water given after a delay. The amount of immediate water was systematically adjusted as a function of the rats' previous choices. This procedure was used to determine the indifference point at which each rat chose the immediate amount and the delayed amount with equal frequency. The amount of immediate water at this indifference point was used to estimate the value of the delayed amount of water. In Experiment 1, the effects of daily changes in the delay to the fixed reinforcer (100 microliters of water delivered after 0, 2, 4, 8, or 16 s) were tested. Under these conditions, the rats reached indifference points within the first 30 trials of each 60-trial session. In Experiment 2, the effects of water deprivation level on discounting of value by delay were assessed. Altering water deprivation level affected the speed of responding but did not affect delay discounting. In Experiment 3, the effects of varying the magnitude of the delayed water (100, 150, and 200 microliters) were tested. There was some tendency for the discounting function to be steeper for larger than for smaller reinforcers, although this difference did not reach statistical significance. In all three experiments, the obtained discount functions were well described by a hyperbolic function. These experiments demonstrate that the adjusting-amount procedure provides a useful tool for measuring the discounting of reinforcer value by delay.     

Key-peck probability and topography in a concurrent variable-interval variable-interval schedule with food and water reinforcers.

The relation between variables that modulate the probability and the topography of key pecks was examined using a concurrent variable-interval variable-interval schedule with food and water reinforcers. Measures of response probability (response rates, time allocation) and topography (peck duration, gape amplitude) were obtained in 5 water- and food-deprived pigeons. Key color signaled reinforcer type. During baseline, response rates and time allocations were greater to the food key than to the water key, and food-key pecks had larger gapes and shorter durations. Relative probability measures (for the food key) were increased by prewatering and decreased by prefeeding. Deprivation effects upon topography measures were apparent only when food- and water-key pecks were analyzed separately. Food-key gape amplitudes increased with prewatering and decreased with prefeeding. The clearest effect occurred with prewatering. There were no consistent effects upon water-key gapes. The key color-reinforcer relation was reversed for 3 pigeons to determine how response topography was modulated during the transition from food- to water-key pecks. Reacquisition was faster for the probability than for the topography measures. Analysis of gape-amplitude distributions during reversal indicated that response-form modulation proceeded through the generation of intermediate gape sizes.     

ESTABLISHING DISCRIMINATIVE CONTROL OF RESPONDING USING FUNCTIONAL AND ALTERNATIVE REINFORCERS DURING FUNCTIONAL COMMUNICATION TRAINING

Functional communication training (FCT) is a popular treatment for problem behaviors, but its effectiveness may be compromised when the client emits the target communication response and reinforcement is either delayed or denied. In the current investigation, we trained 2 individuals to emit different communication responses to request (a) the reinforcer for destructive behavior in a given situation (e.g., contingent attention in the attention condition of a functional analysis) and (b) an alternative reinforcer (e.g., toys in the attention condition of a functional analysis). Next, we taught the participants to request each reinforcer in the presence of a different discriminative stimulus (S^D). Then, we evaluated the effects of differential reinforcement of communication (DRC) using the functional and alternative reinforcers and correlated S^Ds, with and without extinction of destructive behavior. During all applications, DRC (in combination with S^Ds that signaled available reinforcers) rapidly reduced destructive behavior to low levels regardless of whether the functional reinforcer or an alternative reinforcer was available or whether reinforcement for destructive behavior was discontinued (i.e., extinction).