A PRELIMINARY PROCEDURE FOR PREDICTING THE POSITIVE AND NEGATIVE EFFECTS OF REINFORCEMENT-BASED PROCEDURES

In the current investigation, a modification was made to the preference assessment described by Pace, Ivancic, Edwards, Iwata, and Page (1985) to predict the effects of stimuli when used in a differential-reinforcement-of-other-behavior (DRO) schedule for 2 clients with severe self-injurious behavior (SIB) and profound mental retardation. Based on the results of the preference assessment, three types of stimuli were identified: (a) high-preference stimuli associated with high rates of SIB (HP/HS), (b) high-preference stimuli associated with relatively lower rates of SIB (HP/LS), and (c) low-preference stimuli associated with low rates of SIB (LP/LS). Consistent with the results of the preference assessment, the DRO schedule with HP/HS stimuli resulted in increased SIB, and the DRO schedule with LP/LS stimuli resulted in no changes in SIB. HP/LS stimuli were demonstrated reinforcers but did not result in a change in SIB when used in a DRO schedule. Thus, the stimulus preference assessment may be useful clinically in some situations for predicting both the beneficial and the negative side effects of stimuli in DRO procedures.     

Token reinforcement, choice, and self-control in pigeons.

Pigeons were exposed to self-control procedures that involved illumination of light-emitting diodes (LEDs) as a form of token reinforcement. In a discrete-trials arrangement, subjects chose between one and three LEDs; each LED was exchangeable for 2-s access to food during distinct posttrial exchange periods. In Experiment 1, subjects generally preferred the immediate presentation of a single LED over the delayed presentation of three LEDs, but differences in the delay to the exchange period between the two options prevented a clear assessment of the relative influence of LED delay and exchange-period delay as determinants of choice. In Experiment 2, in which delays to the exchange period from either alternative were equal in most conditions, all subjects preferred the delayed three LEDs more often than in Experiment-1. In Experiment 3, subjects preferred the option that resulted in a greater amount of food more often if the choices also produced LEDs than if they did not. In Experiment 4, preference for the delayed three LEDs was obtained when delays to the exchange period were equal, but reversed in favor of an immediate single LED when the latter choice also resulted in quicker access to exchange periods. The overall pattern of results suggests that (a) delay to the exchange period is a more critical determinant of choice than is delay to token presentation; (b) tokens may function as conditioned reinforcers, although their discriminative properties may be responsible for the self-control that occurs under token reinforcer arrangements; and (c) previously reported differences in the self-control choices of humans and pigeons may have resulted at least in part from the procedural conventions of using token reinforcers with human subjects and food reinforcers with pigeon subjects.     

Effects of cocaine on briefly signaled versus completely signaled delays to reinforcement.

Key pecking by 4 pigeons was maintained by a multiple schedule consisting of two variable-interval 60-s schedules wherein each food presentation followed a nonresetting 27-s delay that was either briefly signaled at its outset or completely signaled. Brief-signal duration was adjusted so that response rates maintained by the briefly and completely signaled delays of reinforcement were similar. In general, acute administration of small to intermediate doses (0.3 to 3.0 mg/kg) of cocaine produced either small increases in response rates in both components or no change, and larger doses (5.6 to 13.0 mg/kg) decreased response rates. Chronic (i.e., daily) cocaine administration (10.0 mg/kg) resulted in tolerance to the rate-decreasing effects in both components. Cocaine's effects were generally similar whether delays were completely or briefly signaled. Discontinuation of cocaine administration and subsequent removal of the delay signals also had similar effects in both components of the multiple schedule. Taken together, these results are consistent with the view that the two types of delay signals were equally effective in maintaining responding during the variable-interval schedules.     

Changeover behavior and preference in concurrent schedules

Pigeons were trained on a multiple schedule of reinforcement in which separate concurrent schedules occurred in each of two components. Key pecking was reinforced with milo. During one component, a variable-interval 40-s schedule was concurrent with a variable-interval 20-s schedule; during the other component, a variable-interval 40-s schedule was concurrent with a variable-interval 80-s schedule. During probe tests, the stimuli correlated with the two variable-interval 40-s schedules were presented simultaneously to assess preference, measured by the relative response rates to the two stimuli. In Experiment 1, the concurrently available variable-interval 20-s schedule operated normally; that is, reinforcer availability was not signaled. Following this baseline training, relative response rate during the probes favored the variable-interval 40-s alternative that had been paired with the lower valued schedule (i.e., with the variable-interval 80-s schedule). In Experiment 2, a signal for reinforcer availability was added to the high-value alternative (i.e., to the variable-interval 20-s schedule), thus reducing the rate of key pecking maintained by that schedule but leaving the reinforcement rate unchanged. Following that baseline training, relative response rates during probes favored the variable-interval 40-s alternative that had been paired with the higher valued schedule. The reversal in the pattern of preference implies that the pattern of changeover behavior established during training, and not reinforcement rate, determined the preference patterns obtained on the probe tests.     

ASSESSMENT AND TREATMENT OF DESTRUCTIVE BEHAVIOR MAINTAINED BY STEREOTYPIC OBJECT MANIPULATION

In the current investigation, 2 participants with mental retardation displayed property destruction and stereotypy, and both responses involved the same materials (e.g., breaking and tapping plastic objects). Three experiments were conducted (a) to indirectly assess the functions of these two responses, (b) to determine their relation to one another, and (c) to develop a treatment to reduce the more serious behavior, property destruction. In Experiment 1, previously destroyed materials were either present or absent, and their presence reduced property destruction but not stereotypy. In Experiment 2, matched toys (ones that produced sensory stimulation similar to stereotypy) were either present or absent, or were replaced by unmatched toys (for 1 participant). Matched toys produced large reductions and unmatched toys produced small reductions in property destruction and stereotypy. In Experiment 3, attempts to pick up undestroyed objects were either blocked or not blocked while matched toys were continuously available. Response blocking reduced property destruction (and attempts), prevented stereotypy, and increased manipulation of matched toys. These results suggest that the two aberrant responses formed a chain (e.g., breaking and then tapping the object), which was maintained by the sensory consequences (e.g., auditory stimulation) of the terminal response, and that previously destroyed material or matched toys made the initial response (property destruction) unnecessary.     

Teaching peer reinforcement and grocery words: An investigation of observational learning and instructive feedback

A multiple probe across behaviors design, replicated across participants, assessed the effectiveness of constant time delay in teaching appropriate peer reinforcement and grocery words to 3 elementary students with moderate intellectual disabilities. Additionally, pretests and posttests assessed the acquisition of the participants' observational learning (acquisition of peers' grocery words) and instructive feedback (related information supplied by the teacher in the consequent event). Results indicate that the participants learned (a) how to appropriately reinforce peers, (b) to read their grocery words, (c) some of the targeted stimuli of their peers, and (d) much of the instructive feedback that was associated with each of the grocery words. Maintenance data indicate that the participants maintained their target grocery words at high levels of accuracy.     

Effects of differential reinforcement on the behavior and self-esteem of children with emotional and behavioral disorders

Students in a residential special school for children with emotional and behavioral disorders participated in a study designed to reduce their levels of inappropriate behavior. The residential care staff rated the students' behavioral problems and their class teachers rated their overt self-esteem pre and post intervention. In addition, the students completed self-ratings of their self-esteem. The students were divided into two groups, experimental and control. A multiple baseline across behaviors design was used to assess behavioral changes in the experimental group. Both groups received tangible rewards to the same level but only the experimental group received them contingent upon behaving appropriately. Results showed that the experimental group students made substantial reductions in their levels of inappropriate behavior, which were maintained at a three-month followup. Also, ratings of their behavioral problems by residential child care staff suggested that this improvement in behavior had generalized beyond the classroom to the residential setting. However, no significant differences were found between the pre- and post-intervention ratings of their self-esteem or teacher ratings of their overt self-esteem.     

The relative law of effect: effects of shock intensity on response strength in multiple schedules

Key pecking of four birds was reinforced with food according to a two-component multiple variable-interval 1-minute variable-interval 4-minute schedule. In addition, key pecking was punished by a brief shock according to a variable-interval 30-second schedule during both components of the multiple schedule. The intensity of the shock was varied. For all birds, punishment had a stronger suppressive effect on the responding maintained by the leaner food schedule, and the ratio of responding during the two components of the multiple schedule became closer to the ratio of reinforcement as shock intensity was increased, as the relative law of effect predicts. At the higher shock intensity, there was some evidence that the ratio of responses overmatched the ratio of reinforcements.     

A molar theory of reinforcement schedules

Behavior of subjects exposed to concurrent and individual interval and ratio schedules of reinforcement may be described in terms of a set of expressions relating the value of responses to their durations, a feedback equation relating reinforcement to response duration, and the assumption that subjects allocate their time among various responses so as to maximize value.