Preference for mixed versus constant delay of reinforcement

Preference for constant and mixed delay of reinforcement was studied using concurrent equal variable-interval schedules. For four pigeons, pecking one key was reinforced following constant delays of 8 sec and mixed delays of 6 or 10 and 2 or 14 sec. Pecking a second key was reinforced following constant delays of 0, 8, 16, and 32 sec. For two additional pigeons, pecking one key was reinforced following delays of 30, 15 or 45, 5 or 55, and 0 or 60 sec. Reinforcements on the other key were delayed 30 sec. It was found that (a) pigeons preferred mixed relative to constant delay of reinforcement, and (b) preference for mixed delay of reinforcement increased as the range of delay interval variability increased.     

Response-shock delay as a reinforcer in avoidance behavior

After rats received preliminary training to avoid shock on a discrete-trial retractable-bar avoidance procedure, the procedure was changed such that responses retracted the lever but did not affect the rate of shock. Responses only delayed the onset of shock. About half of the animals under these procedures responded consistently on almost 100% of the discrete-trial cycles over days. When short latencies maximized the response-shock delay, animals tended to make short-latency responses. When long latencies maximized the response-shock delay, animals tended to make long-latency responses. When all response latencies produced the same response-shock delay, animals made differing average-latency responses. And, when responses did not delay shock, most of the animals primarily engaged in shock-elicited responding while the other animals engaged in preshock responding.     

INCREASING SPONTANEOUS VERBAL RESPONDING IN AUTUSTIC CHILDREN USING A TIME DELAY PROCEDURE

One oft-cited problem with teaching speech skills to autistic children isthe failure of the speech to be spontaneous. That is, the children's speech often remains underthe control of the verbal behavior of others rather than underthe control of other nonverbal referents inthe environment. We investigatedthe effectiveness of a time delay procedure to increasethe spontaneous speech of seven autistic children. Initially, the experimenter presented a desired object (e.g., cookie) and immediately modeledthe appropriate response “I want (cookie).” Gradually, asthe child imitatedthe vocalization, the experimenter increasedthe time between presentation of the object andthe modeled vocalization in an attempt to transfer stimulus control of the child's vocalization fromthe experimenter's model tothe object. Results indicated that allthe children learned to request items spontaneously and generalized this behavior across settings, people, situations, and to objects which had not been taught. These results are discussed in relation tothe literature on spontaneous speech, prompting, and generalization.     

THE ROLE OF RESPONSE DELAY IN IMPROVING THE DISCRIMINATION PERFORMANCE OF AUTISTIC CHILDREN

This study investigated the influence of a response delay requirement on the discrimination performance of autistic children. In the context of a multiple baseline design with subsequent repeated reversals, two conditions were compared: a no-response-delay condition, where the child was allowed to make the target response immediately after presentation of the discriminative stimulus versus a response-delay condition, where the target response was permitted three seconds following the discriminative stimulus when the therapist would signal the child to respond. The results showed that the response-delay condition produced higher levels of correct responding than the no-response-delay condition. In addition, teachers in the research setting rated the response-delay procedure to be a practical and effective teaching technique that could be implemented in a classroom setting. The results were discussed in relation to the literature on impulsivity, and were interpreted as indicating that the response-delay procedure provides a valuable technique for teaching autistic children.     

Changeover delay effects on topographically tagged discriminative behavior

In a multiple variable-interval extinction schedule, pigeons' responses on an operant key were differentially reinforced in the presence of discriminative stimuli located on a signal key. Changeover delays of zero, one, two, or four seconds specified the time following a signal-key response within which an operant-key response was not reinforced. Systematic reduction of signal-key response rates with increasing changeover-delay duration indicated that signal-key responding was largely maintained by reinforcement of adventitious signal-key/operant-key response chains.     

Briefly delayed reinforcement: An interresponse time analysis

Key-peck responding of pigeons was compared under VI or DRL schedules arranging immediate reinforcement and briefly (.5 sec) delayed reinforcement. Delays were either signaled by a blackout in the chamber, unsignaled, or unsignaled with an additional requirement that responding not occur during the .5 sec interval immediately preceding reinforcement (response delay). Relative to the immediate reinforcement condition, response rates increased during the unsignaled delay, decreased during the signaled delay, and were inconsistent during the response delay condition. An analysis of interresponse times (IRTs) under the different conditions revealed a substantial increase in the frequency of short (0 to .5 sec) IRTs during the unsignaled condition and generally during the response delay conditions compared to that during the immediate reinforcement baseline. Signaled delays decreased the frequency of short (0 to .5 sec) IRTs relative to the immediate reinforcement condition. The results suggest that brief unsignaled delays and, in many instances, response delays increase the frequency of short IRTs by eliminating constraints on responding.     

An invariant relation between changing over and reinforcement

Although concurrent schedules may arrange reinforcers irregularly, relatively large numbers of reinforcers are obtained when an animal changes from one schedule to the other. This paper proposes a quantitative relation that predicts the proportion of reinforcers obtained when an animal is working on a schedule and the proportion when the animal changes over to a schedule. Basically the relation states that the number of reinforcers obtained while an animal works on a schedule varies directly with the relative amount of time spent working on that schedule; and the number of reinforcers obtained when an animal changes to a schedule varies directly with the relative amount of time spent on the alternate schedule. An important aspect of this relation is that when relative reinforcement rates are less than .50, more reinforcers are obtained just after an animal changes to a schedule than at all other times when this schedule is engaged. Data obtained both from a stat-bird and a live pigeon were in close agreement with the quantitative predictions. The relation between changing over and reinforcement held across several procedural changes that included changes in relative reinforcement rate, changes from independent to interdependent scheduling procedures, and changes in the variable-interval reinforcement distributions. The results are discussed in terms of the effects of the local distribution of reinforcement on responding. The local reinforcement distribution can affect local response rates and affects the resulting matching relation. This arrangement has implications for explanations of choice.     

“DO I HAVE TO BE GOOD ALL DAY?” THE TIMING OF DELAYED REINFORCEMENT AS A FACTOR IN GENERALIZATION

Delayed reinforcement, sometimes delivered just after the setting in which the critical behavior had occurred (Early), and sometimes delivered only after several further settings had been encountered (Late), was used to improve a variety of behaviors in seven preschool children, and to control their generalization. Performance of those behaviors was measured in two classroom settings: the Contingent setting, within which performance of the specified behavior determined the later (Early or Late) reinforcement, and the Generalization setting, in which there were no experimental contingencies, immediate or delayed, for the performance of the same behavior. Performances by all children in the Contingent setting were controlled by delayed reinforcement, whether Early or Late. All children showed consistent generalization from the Contingent setting to the Generalization setting during the Late condition, when reinforcement was delivered at the end of the school day. Generalization did not occur during the Early condition, when reinforcement was provided immediately after the Contingent setting (prior to the Generalization setting), unless that condition had been preceded by a Late condition (as it was for S₆ and S₇). The results suggest that the Late timing of delayed reinforcement was an effective and efficient generalization-promotion technique for performances that did not generalize spontaneously.     

TEACHERS' GENERALIZED USE OF DELAY AS A STIMULUS CONTROL PROCEDURE TO INCREASE LANGUAGE USE IN HANDICAPPED CHILDREN

In Experiment 1, classroom teachers were taught to delay their offers of help in naturally occurring situations, and thereby to provide additional opportunities for language use by six moderately retarded language-delayed children. The teachers introduced this delay technique in a multiple-baseline design across the six children. As delays were used, child verbal initiations increased. Follow-up assessment showed that teachers were maintaining greater than baseline levels of the delay technique after 10 weeks. Experiment 2 replicated the findings of Experiment 1, and included a more thorough maintenance assessment, while focusing on teachers' generalization of the delay technique. Teachers were found to generalize their use of delay to 56% of their monitored untaught opportunities. The two experiments show that (a) the delay technique is quick to teach and simple to implement, (b) delays do provide opportunities for children to initiate, (c) teachers can generalize their use of delay to novel self-selected situations, and (d) teachers can maintain their use of delays over time.     

Judging the strength of designated evidence

Judgments of evidence strength were obtained in a series of vignettes, each containing one or two items of evidence for each of two logically independent hypotheses. Each judgment concerned a designated subset of the presented evidence. Different groups of subjects encountered different but overlapping sets of evidence. We compared groups that judged the same designated evidence for the same hypothesis, but differed in exposure to surrounding (nondesignated) evidence. Results showed clear separation of relevant from irrelevant evidence and of designated from surrounding relevant evidence. This was particularly clear in the second experiment, where judgments of designated evidence remained invariant whether the surrounding evidence supported or contradicted the specified hypothesis. The conjunction fallacy was observed for judgments of evidence strength, but was substantially reduced by a simple instruction. Because subjects can separate evidence, it becomes possible to construct cardinally scaled standards of evidence strength using conjoint-measurement methods.