Performance in concurrent interval schedules: a systematic replication

Five pigeons were trained on a variety of concurrent interval schedules that arranged reinforcements at either fixed or variable times after the last reinforcement. Two measures were obtained: the number of responses on each schedule, and the time spent responding on each schedule. Ratios of response rates on the two schedules did not equal ratios of reinforcement rates when both schedules were variable nor when one was variable and the other fixed. Ratios of times spent responding approximately equalled ratios of reinforcement rates when both schedules were variable, but did not do so when one was fixed.     

SOME EFFECTS OF REINFORCEMENT SCHEDULES IN TEACHING PICTURE NAMES TO RETARDED CHILDREN1

The effects of several different schedules of primary reinforcement were compared in a picture-naming task with retarded children. In Experiment I, number of correct responses and learning rate were higher under fixed-ratio schedules than under continuous reinforcement. In Experiment II, number of correct responses and learning rate tended to be greater under intermediate than under low or high fixed-ratio schedules. In Experiment III, number of correct responses was higher under interlocking schedules, in which the response requirement increased with time following the previous reinforcement, than under comparable fixed-ratio schedules. Learning rates were generally low and, perhaps because of this, not very different under the two types of schedules in this experiment. Accuracy (i.e., proportion of trials on which correct responses occurred) was typically high and insensitive to variations in schedule and schedule parameter throughout each experiment.     

Conscious knowledge of CS-UCS contingency information affects extinction retrieval of conditioned disgust responses: Findings from an online de novo disgust conditioning task

ObjectiveThe present study aimed to establish and develop an online de novo conditioning paradigm for the measurement of conditioned disgust responses. We further explored the effects of explicit instructions about the CS-UCS contingency on extinction learning and retrieval of conditioned disgust responses.MethodThe study included a sample of 115 healthy participants. Geometric figures served as conditioned stimuli (CS) and disgust-evoking pictures as unconditioned stimuli (UCS). During disgust conditioning, the CS+ was paired with the UCS (66% reinforcement) and the CS- remained unpaired; during extinction and retrieval, no UCS was presented. Half of the participants (n = 54) received instructions prior to the disgust extinction stating that the UCS will not be presented anymore. 1-2 days or 7-8 days later participants performed a retrieval test. CS-UCS contingency, disgust and valence ratings were used as dependent measures.ResultsSuccessful acquisition of conditioned disgust response was observed on the level of CS-UCS contingency, disgust and valence ratings. While some decline in valence and disgust ratings during the extinction stage was observed, contingency instructions did not significantly affect extinction performance. Retrieval one week later revealed that contingency instructions increased the discrimination of the CSs.ConclusionsExtinction of conditioned disgust responses is not affected by explicit knowledge of the CS-UCS contingencies. However, contingency instructions prior to extinction seem to have a detrimental effect on long-term extinction retrieval.     

Instructions and reinforcement in the observing behavior of adults and children

Observing responses of college students and children of different ages (4 to 5, 9 to 10, and 13 to 14 years) were studied using two-component schedules of reinforcement. Different frequencies or numbers of points were given in the components and points were backed by either money or instructions about getting points (e.g., “points are for the experimenter's information only”). Stimuli that were either correlated or uncorrelated with the components were contingent on presses on either of two concurrently available levers (observing responses). In each of three experiments, preferences for stimuli were consistent with the conditioned-reinforcement hypothesis of observing but inconsistent with the uncertainty-reduction hypothesis. Stimulus preferences were established, eliminated, or reversed by instructions about the significance of getting points not backed with money. Instructions to in effect ignore points with no monetary value eliminated stimulus preference provided that money was not associated with points in other conditions for the same subjects. Stimulus preferences were otherwise independent of monetary point value. Instructions that described reinforcement contingencies promoted more rapid adjustment to the contingencies than occurred without them, and preferences were less variable across sessions within subjects and were on the average more extreme. Although some results involving absolute rates of observing depended upon the age of subjects, stimulus preferences did not. The data suggest that the conditioned-reinforcement hypothesis of observing has considerable generality for humans in choice procedures in the laboratory. That monetary value of points did not affect preferences in a graded fashion is consistent with versions of the conditioned-reinforcement hypothesis which emphasize reduction in delay to reinforcement over other reinforcement parameters.     

Children's acquisition and reversal behavior in a probability learning situation as a function of programed instruction,internal-external control,and schedules of reinforcement

A three-choice, contingent task was used with 192 fifth and sixth graders in a 2 × 2 × 3 factorial design combining instruction (programed instruction on selected probability concepts vs no programed instruction), locus of control (internal vs external), and schedules of reinforcement (33, 66, and 100%). The dependent measures were the percentage of correct acquisition responses, of correct reversal responses, and of pattern responses, as well as posttests on probability concepts. The major findings of the study were associated with schedule of reinforcement. In acquisition and reversal, Ss under 100% reinforcement during acquisition tended to maximize the greatest, followed by the 66 and 33% conditions, in that order. The ordinal relationship among schedules was the exact reverse of the maximizing approach for the pattern responses. A partial reinforcement effect was obtained in reversal. Evidence indicated that programed instruction and locus of control affected maximizing behavior, patterning behavior, and resistance to extinction (though these variables did not interact with reinforcement schedule in the predicted direction). Finally the posttest data showed that instructed Ss did learn more relative to noninstructed Ss.     

Generating variable and random schedules of reinforcement using Microsoft Excel macros

Variable reinforcement schedules are used to arrange the availability of reinforcement following varying response ratios or intervals of time. Random reinforcement schedules are subtypes of variable reinforcement schedules that can be used to arrange the availability of reinforcement at a constant probability across number of responses or time. Generating schedule values for variable and random reinforcement schedules can be difficult. The present article describes the steps necessary to write macros in Microsoft Excel that will generate variable-ratio, variable-interval, variable-time, random-ratio, random-interval, and random-time reinforcement schedule values.     

Contingency-shaped and rule-governed behavior: instructional control of human loss avoidance

Instructions can override the influence of programmed schedules of reinforcement. Although this finding has been interpreted as a limitation of reinforcement schedule control in humans, an alternative approach considers instructional control, itself, as a phenomenon determined by subjects' reinforcement histories. This approach was supported in a series of experiments that studied instructional and schedule control when instructions either did or did not accord with the schedule of reinforcement. Experiment I demonstrated that accurate instructions control discriminative performances on multiple avoidance schedules, and that such control persists in a novel discrimination. Experiments II and III showed that elimination of instruction-following occurs when inaccurate instructions cause subjects to contact a monetary loss contingency. Experiment IV demonstrated the reinforcing properties of accurate instructions. Skinner's view of rule-governed behavior is consistent with these findings, and can be extended to account for many aspects of instructional control of human operant behavior.     

Effects of instructional constraints on human fixed-interval performance

Several groups of human subjects were exposed to a variety of experimental conditions involving a fixed-interval 27-second schedule of reinforcement in compound with instructions to constrain in the number of responses within the interreinforcement interval and/or the duration of the experimental session. One group was further exposed to a contingency involving the placement of responses within the IRI. A diversity of patterns of performance was observed, including those typically associated with animal subjects exposed to FI schedules. Generally, the imposition of instructions to minimize session duration reduced post-reinforcement pausing and increased overall reinforcement density from those levels obtained with only instructions to expend a given number of responses per reinforcer. The results are seen to underscore the sensitivity of human fixed-interval performance and the contribution of extra-experimental contingencies.     

Joint Influence of Prior Beliefs and Current Situational Information on Stable and Unstable Attributions

Abstract

The present study was designed to assess the joint effects of situational information and the individual's attributional style on the choice and consequences of a stable or unstable attribution for failure. Israeli undergraduates were divided according to their attributional style for negative events into stable, undefined, and unstable attributors and were exposed to no-feedback or failure conditions in which they received instructions encouraging them to attribute failure to stable or unstable causes. Results indicate that the choice of a stable or unstable attribution for failure was influenced mainly by situational cues and that the individual's attributional style contributed to subsequent expectancies and the quality of performance following failure.     

Context, observing behavior, and conditioned reinforcement

Pigeons made observing responses for stimuli signalling either a fixed-interval 30-sec schedule or a fixed-ratio x schedule, where x was either 20, 30, 100, 140, or 200 and the schedules alternated at random after reinforcement. If observing responses did not occur, food-producing responses occurred to a stimulus common to both reinforcement schedules. When the fixed-interval schedule was paired with a low-value fixed ratio, i.e., 20 or 30, the presentation of the stimulus reliably signalling the fixed-ratio schedule reinforced observing behavior, but the presentation of the stimulus reliably signalling the fixed-interval schedule did not. The converse was the case when the fixed-interval schedule was paired with a large-valued fixed ratio, i.e., 100, 140, or 200. The results demonstrated that the occasional presentation of the stimulus signalling the shorter interreinforcement interval was necessary for the maintenance of observing behavior. The reinforcement relationship was a function of the schedule context and was reversed by changing the context. Taken together, the results show that the establishment and measurement of conditioned reinforcement is dependent upon the context or environment in which stimuli reliably correlated with differential events occur.     

Conditioned suppression and variable ratio reinforcement

Conditioned suppression is a decrease in response rate during a relatively short duration stimulus that terminates independently of the animal's behavior and coincidentally with a brief unavoidable shock. The degree of conditioned suppression was measured for each of three birds on three variable ratio schedules; that is, the number of responses required for food reinforcement was varied around a mean of 50, 100, or 200. The results indicated a slight and possibly negligible decrease in the degree of suppression as the mean number of responses required on the schedule was increased from 50, to 100, and 200. In general, it was found that all of the variable ratio schedules tested were quite insensitive to the conditioned suppression procedure, although almost complete suppression was obtained on a few occasions. Since the reinforcement was contingent upon the emission of responses, the birds typically displayed a high rate of response during the pre-shock stimulus on all schedules. In addition, the rate during the pre-shock stimulus often changed abruptly independent of the presentation of a reinforcement. As a result of the high rate of response and the abrupt changes in rate, the degree of suppression from trial to trial was quite variable. A clear analysis of an experimental variable on this baseline is thus difficult.     

Continuous, fixed-ratio, and fixed-interval reinforcement in honey bees

Bees learned to enter a Plexiglas tube and to suck small portions of sugar solution; every entry or every fifth entry was reinforced. During an extinction phase, the bees on the fixed-ratio schedule emitted twice as many responses as did those given continuous reinforcement. Bees on a fixed-interval schedule of reinforcement emitted lower response rates than did those given fixed-ratio reinforcement. By extending the conditioning procedure for several days, it was possible to maintain responding with fixed-ratio schedules requiring 30 responses per reinforcement and with fixed-interval values up to 90 sec. Under fixed-interval schedules, response rates did not increase toward the end of the reinforcement intervals.     

Predator videos and electric shock function as punishers for zebrafish (Danio rerio)

Zebrafish (Danio rerio) are a promising animal model for studying the effects of gene–environment interactions on behavior. Two experiments were conducted to assess punishment effects of presenting predator videos (Indian leaf fish; Nandus nandus) and electric shock on operant approach responses in zebrafish. In Experiment 1, the predator video and shock stimuli were presented upon a response maintained by a single variable‐interval schedule of food reinforcement in different groups of fish. In Experiment 2, the predator video and shock stimuli were presented upon one of two response alternatives maintain by concurrently available variable‐interval schedules of food reinforcement in different groups of fish. Responding decreased when the predator video and shock stimuli were presented relative to their absence in both experiments. Moreover, responding on an unpunished alternative did not reliably decrease in Experiment 2. These results indicate that the decrease in responding resulted from the punishment contingency rather than from elicited species‐specific defense responses or conditioned avoidance. Thus, the predator video and electric shock functioned as punishers of operant behavior for zebrafish. Identifying punishers for this species could lead to research on how gene–environment interactions influence individual differences in sensitivity to punishment.     

The Effects of Magnitude-Based Differential Reinforcement on the Skill Acquisition of Children with Autism

A common recommendation for teaching skills to children with autism is to apply differential reinforcement by reserving high-quality reinforcement for unprompted responses (Sundberg and Partington in Teaching language to children with autism or other developmental disabilities, Behavior Analysts Inc., Pleasant Hill, 1998). Earlier research focuses primarily on schedules or quality of reinforcement, rather than magnitude of reinforcement, when evaluating the use of differential reinforcement in practice. The utility of magnitude-based differential reinforcement may be dependent upon evidence that a learner responds differentially to large and small amounts of reinforcement such that he or she selects the large amount of reinforcement over the small amount of reinforcement and engages in more responses that produce the relatively larger magnitude reinforcement. Three individuals with autism participated in a treatment comparison of differential reinforcement. The manipulation of magnitude of differential reinforcement in a skill acquisition program did not have an appreciable effect on the rate of acquisition for any of the three participants.     

The effect of two schedules of primary and conditioned reinforcement

Of 23 pigeons, 11 received continuous reinforcement for key pecking, and 12 received an FR 10 schedule of reinforcement. The birds were then tested without food, but with potential conditioned reinforcers presented either on the same schedule as in training, on the other schedule, or not at all. Each bird in the subgroup trained on CRF and tested with S^r's at FR 10 not only gave more responses in testing than did each bird in both subgroups receiving no S^r's, but also gave more responses than did each bird in the S^r subgroup receiving CRF training and S^r's at CRF. Cumulative records are presented to show the effects of different schedules of conditioned reinforcers.     

The role of discriminative stimuli in concurrent performances

Key pecking in pigeons was examined under concurrent and parallel arrangements of two independent and simultaneously available variable-interval schedules. Pecks on the changeover key alternated the schedule of reinforcement for responses on the main key. Under concurrent schedules, discriminative stimuli were paired with the reinforcement schedule arranged in each component and changeover responses also alternated these stimuli. Under parallel schedules, changeover responses alternated the effective reinforcement schedule, but did not change the discriminative stimulus. On concurrent procedures, changeover response rate was inversely related to the difference in reinforcement rate between the two components, whereas on parallel schedules no consistent relationship was found. With both schedules, absolute response and reinforcement rates were positively related, although for a given set of reinforcement frequencies, rates were often higher on the concurrent schedules. On concurrent schedules, relative response rates and relative times were equal to relative reinforcement rates. On parallel schedules these ratios were positively related, but response and time ratios were much smaller than were obtained with comparable concurrent schedules. This inequality was most pronounced when absolute reinforcement frequencies were lowest.     

Dissociation of value and response strength

Four pigeons were exposed to multiple schedules and later to concurrent-chains schedules, with terminal links that had previously been multiple-schedule components. For 2 birds, the terminal-link schedules arranged an inverse relationship between response rate and reinforcement rate; for the other 2 birds a direct corresponding relationship was arranged. Those response rates were further modified by differentially reinforcing either longer or shorter interresponse times, relative to the current means. Although the birds' initial-link responses indicated preferences for terminal links with higher rates of reinforcement, in half the cases the birds responded during the terminal links in such a way as to produce lower rates of reinforcement, rates their initial-link behavior indicated they did not prefer. That outcome is inconsistent with maximization theory, but consistent with a strengthening analysis of behavior on single-key schedules.     

Preference for and effects of variable-as opposed to fixed-reinforcer duration

Pigeons were trained on multiple schedules in which a fixed number of pecks produced either a fixed or a variable period of access to food, the average variable-duration reinforcement equalling the fixed. Pecking rates were generally higher during the variable-duration component. Subsequent performance on concurrent schedules revealed an initial preference for variable-duration reinforcement for all subjects; for most subjects, this preference was sustained. For one subject, the average variable duration was gradually reduced to half the fixed duration: continued preference for the variable component resulted in a loss of up to 30% of available reinforcement time. A return to multiple schedules with unequal pay-off shifted the preference to the greater fixed duration, and this preference was maintained even when the variable duration was again raised to equal the fixed duration. For the remaining subjects, the initial variable-duration preference on concurrent schedules was gradually replaced by a side preference. When the range of variable durations was varied, keeping the average variable duration equal to the fixed, the occasional longer reinforcers sustained a preference for variable-reinforcer durations for three of the four subjects.     

More on concurrent interval-ratio schedules: a replication and review.

It has been suggested that the failure to maximize reinforcement on concurrent variable-interval, variable-ratio schedules may be misleading. Inasmuch as response costs are not directly measured, it is possible that subjects are optimally balancing the benefits of reinforcement against the costs of responding. To evaluate this hypothesis, pigeons were tested in a procedure in which interval and ratio schedules had equal response costs. On a concurrent variable time (VT), variable ratio-time (VRT) schedule, the VT schedule runs throughout the session and the VRT schedule is controlled by responses to a changeover key that switches from one schedule to the other. Reinforcement is presented independent of response. This schedule retains the essential features of concurrent VI VR, but eliminates differential response costs for the two alternatives. It therefore also eliminates at least one significant ambiguity about the reinforcement maximizing performance. Pigeons did not maximize rate of reinforcement on this procedure. Instead, their times spent on the alternative schedules matched the relative rates of reinforcement, even when schedule parameters were such that matching earned the lowest possible overall rate of reinforcement. It was further shown that the observed matching was not a procedural artifact arising from the constraints built into the schedule.