Effects of Lag Schedules and Response Blocking on Variant Food Consumption by a Girl with Autism

Food selectivity by individuals with autism spectrum disorder (ASD) is often viewed in the behavioral literature as a problem with compliance and treated accordingly. However, when viewed as a problem with invariance, it may be appropriate to treat the problem by using procedures that increase variant food consumption. Lag schedules of reinforcement have been shown to increase variability in verbal and play behavior of children with ASD. Therefore, we attempted to evaluate the effects of a lag schedule of positive reinforcement on variant food consumption by a girl with ASD and food selectivity. Ultimately, a lack of baseline variability in consumption precluded an evaluation of the programmed lag schedule but suggested that a discovery research approach may be informative. Thus, additional treatment components were added and evaluated in a component analysis. Response blocking of invariant consumption appeared to establish a lag schedule of reinforcement that increased variability and variety in food consumption, which was maintained across changes in the value of the lag schedule. Some potential behavioral processes responsible for the effects and implications for future research are discussed. Copyright © 2016 John Wiley & Sons, Ltd.     

The roles of stimulus control and reinforcement frequency in modulating the behavioral effects of d-amphetamine in the rat.

The behavioral effects of d-amphetamine have been shown to be modulated by stimulus control, with less impairment of performance occurring when control is great. When the fixed-consecutive-number schedule is used (on which at least a specified consecutive number of responses must be made on one operandum before a single response on another will produce a reinforcer), response rate tends to be invariant but reinforcement frequency is not. This study asks whether the differences in reinforcement frequency that usually accompany changes in stimulus control could themselves be responsible for the performance differences. Two versions of the fixed-consecutive-number schedule of reinforcement were combined into a multiple schedule within which stimulus control was varied but differences in reinforcement frequency were minimized by omitting some reinforcer deliveries during the component that usually had the higher reinforcement frequency. In one component, a compound discriminative stimulus was added with the eighth consecutive response on the first lever; a single response on the second lever was then reinforced. In the other component, no such stimulus was presented. With no added stimulus, large decreases occurred in the number of runs satisfying the minimum requirement for reinforcement at doses of drug that produced only minimal changes when an added stimulus controlled behavior. Thus, increased stimulus control diminishes the behavioral changes produced by d-amphetamine even when the possible contribution by baseline reinforcement rate is minimized.     

Contrast, component duration, and the following schedule of reinforcement

Experiment 1 investigated component duration in a four-component multiple schedule designed to separate the effects of the preceding schedule of reinforcement from those of the following schedule of reinforcement. The preceding schedule in the preceding component had no consistent effect regardless of component duration. The following schedule was a powerful determinant of behavior, however, with higher response rates resulting from a following period of extinction. Moreover, the effect of the following schedule was greater with short component durations, which strongly suggests that component-duration effects previously found with multiple schedules are due generally to variation in the degree of control by the following schedule. Experiments 2--4 investigated the basis of the effects of the following schedule. In some situations differential responding in the following component was the controlling variable, but in others it was differential reinforcement in the following component. The results are consistent with the view that response rate during a stimulus is inversely related to the "value" of the following component, where the calculation of value must include both primary and conditioned reinforcement.     

An architect of the golden years

William H. Morse has played a major role in the experimental analysis of behavior. His view of operant behavior as the outcome of differential reinforcement provides an invaluable lesson in scientific research and theory. He studied schedules of reinforcement to generate an in-depth analysis of the complex interactions existing when contingencies exert their control over behavior. He has been instrumental in showing how behavior is determined by the dynamic interaction of factors brought into play by the imposition of any schedule, and he has a remarkably intuitive understanding of the nature of these determining variables. Some of these causal events are imposed directly by the schedule, but others arise in a more indirect manner through necessary constraints. In Morse's view, schedules can be more fundamental in determining behavior than are the scheduled events themselves. Behavior is the shaped product of an organism's history in combination with present environmental conditions. His impact deserves to be more than historical: A study of his work continues to reward the reader with exciting insights into the nature of behavioral control.     

Choice for reinforced behavioral variability in children with autism spectrum disorder

Although individuals with autism spectrum disorder (ASD) tend to behave repetitively, certain reinforcement contingencies (e.g., lag schedules) can be used to increase behavioral variability. In a lag schedule, reinforcers only follow responses that differ from recent responses. The present study was designed to promote variable play behavior in preschoolers with ASD interacting with playsets and figurines and to assess preference for variability and repetition contingencies. Data have shown a preference for variability in pigeons and college students, but this effect has not been explored in clinical populations. In this experiment, preschoolers with ASD were taught to discriminate between variability and repetition contingencies. Only play behaviors that met a lag schedule were reinforced in the presence of one color, and only repetitive behaviors were reinforced in the presence of another. After differential performance was established, participants experienced a concurrent chains schedule. Participants chose between the colors taught in training and then completed a play session with the selected contingency. One participant selected variability and repetition equally. The other participants showed a slight preference for variability. These results indicate that some individuals with ASD may play repetitively, not because they prefer repetition, but because they require additional teaching to play variably.     

Preference between variable-ratio and fixed-ratio schedules: local and extended relations.

Although it has repeatedly been demonstrated that pigeons, as well as other species, will often choose a variable schedule of reinforcement over an equivalent (or even richer) fixed schedule, the exact nature of that controlling relation has yet to be fully assessed. In this study pigeons were given repeated choices between concurrently available fixed-ratio and variable-ratio schedules. The fixed-ratio requirement (30 responses) was constant throughout the experiment, whereas the distribution of individual ratios making up the variable-ratio schedule changed across phases: The smallest and largest of these components were varied gradually, with the mean variable-ratio requirement constant at 60 responses. The birds' choices of the variable-ratio schedule tracked the size of the smallest variable-ratio component. A minimum variable-ratio component at or near 1 produced strong preference for the variable-ratio schedule, whereas increases in the minimum variable-ratio component resulted in reduced preference for the variable-ratio schedule. The birds' behavior was qualitatively consistent with Mazur's (1984) hyperbolic model of delayed reinforcement and could be described as approximate maximizing with respect to reinforcement value.     

EFFECTS OF NONCONTINGENT MUSIC ON VOCAL STEREOTYPY AND TOY MANIPULATION IN CHILDREN WITH AUTISM SPECTRUM DISORDERS

Noncontingent music has been shown to reduce engagement in vocal stereotypy in children with autism spectrum disorders, but its effects on appropriate collateral behavior remain unknown. Given that noncontingent music is typically implemented during periods of free play, clinicians may be concerned with the effects of the intervention on toy manipulation. Thus, we examined the immediate and subsequent effects of noncontingent music on engagement in vocal stereotypy and toy manipulation in four children with autism spectrum disorders by using a three‐component multiple schedule combined with a multi‐element design. The results suggest that noncontingent music (i) reduced immediate engagement in vocal stereotypy for three of four participants, (ii) never increased subsequent engagement in vocal stereotypy, and (iii) produced idiosyncratic effects on immediate and subsequent engagement in toy manipulation for two participants. The clinical implications of the results are discussed in terms of improving the treatment of vocal stereotypy using noncontingent music. Copyright © 2012 John Wiley & Sons, Ltd.     

Effects of d-amphetamine, cocaine, and phencyclidine on the acquisition of response sequences with and without stimulus fading.

In each of three components of a multiple schedule, monkeys were required to emit a different sequence of four responses in a predetermined order on four levers. Sequence completions produced food on a fixed-ratio schedule. Errors produced a brief timeout. One component of the multiple schedule was a repeated-acquisition task where the four-response sequence changed each session (learning). The second component of the multiple schedule was also a repeated-acquisition task, but acquisition was supported through the use of a stimulus-fading procedure (faded learning). In a third component of the multiple schedule, the sequence of responses remained the same from session to session (performance). At higher doses, d-amphetamine, cocaine, and phencyclidine decreased the overall rate of responding and increased the percent errors in all three components. At lower doses, however, the three drugs produced selective effects on errors. Errors were increased in the learning component at lower doses than those required to disrupt the behavior in the faded-learning component. The performance component tended to be the least sensitive to disruptive drug effects. The data are consistent with the view that stimulus fading can modulate the effects of drugs on acquisition.     

Concurrent random-interval schedules and the matching law

In Experiment I, a group of eight pigeons performed on concurrent random-interval schedules constructed by holding probability equal and varying cycle time to produce ratios of reinforcer densities of 1:1, 3:1, and 5:1 for key pecking. Schedules for a second group of seven were constructed with equal cycle times and unequal probabilities. Both groups deviated from simple matching, but the two forms of the schedules appeared to produce no consistent patterns of deviation. The data were found to be consistent with those obtained in concurrent variable-interval situations. The parameters of the matching equation in the form of Y=k X^a were estimated; the value of k was unity and a was 0.84. In Experiment II, six pigeons were exposed to two conc RI RI schedules in which one component increasingly approximated an FI schedule. The value of k was not 1.0. Concurrent RI RI schedules were shown to represent a continuum from conc FI VI to conc VI VI schedules. The use of the exponential equation in testing “matching laws” suggests that a<1 will continue to be observed, and this will set limits on the form of new laws and the assumed or rational values of the component variables in these laws.     

Behavior Genetics: What's New? What's Next?

What's new in behavior genetics? With widespread acceptance that nearly all behavioral variation reflects some genetic influence, current studies are investigating developmental changes in the nature and magnitude of genetic and environmental effects, the extent to which different behaviors are influenced by common genes, and different forms of gene-environment correlation and interaction. New designs, focused on assessment of unrelated children in the same households or neighborhood environments, and use of measured environmental variables within genetically informative designs, are yielding more incisive evidence of common environmental effects on behavior. What will be next? Behavior genetic techniques and analyses will be used to inform efforts to find genes altering susceptibility for disorder and dispositional genes affecting behavioral variation. The developing integration of behavioral and molecular genetics will identify genes influencing specific behavioral variation and enhance understanding of how they do so. Psychologists will play a pivotal role in communicating that understanding to the public and in facilitating consideration of the inevitable ethical issues then to be confronted.     

Tolerance to effects of cocaine on behavior under a response-initiated fixed-interval schedule

Tolerance to effects of cocaine can be modulated by schedules of reinforcement. With multiple ratio schedules, research has shown an inverse relationship between ratio requirement and amount of tolerance that resulted from daily administration of the drug. In contrast, tolerance to the effects of cocaine on behavior under multiple interval schedules generally has developed regardless of interval value. Under interval schedules reinforcement depends on the animal making one response following a time interval. Thus, as time to respond increases, the time to reinforcement decreases. On the other hand, fixed ratio schedules require a specified number of responses to be made prior to reinforcement. Therefore, delaying the initiation of responding does not coincide with a significant decrease in the time to reinforcement. In the current experiment, 6 pigeons were trained to respond under a three-component multiple schedule, with a different tandem fixed-ratio 1 fixed-interval schedule in each component. The multiple schedule required one response, which was followed by one of three fixed-interval values (5, 15, or 60 s). Thus, the multiple schedule was interval-like because after the fixed-ratio 1, only one more response was required for reinforcement, but it was also ratio-like because the length of the pause at the beginning of each interreinforcer interval affected the time until the next reinforcer. Acute administration of cocaine generally resulted in dose-dependent decreases in responding. Chronic (i.e., daily) administration of a rate-decreasing dose resulted in tolerance patterns similar to those usually obtained with multiple ratio schedules. That is, the magnitude of tolerance was related inversely to schedule size. These results suggest that delay to reinforcement from the initial response may play a role in the development of schedule-parameter-related tolerance.     

NONCONTINGENT REINFORCEMENT: A FURTHER EXAMINATION OF SCHEDULE EFFECTS DURING TREATMENT

We conducted 2 studies to determine whether dense and thin NCR schedules exert different influences over behavior and whether these influences change as dense schedules are thinned. In Study 1, we observed that thin as well as dense NCR schedules effectively decreased problem behavior exhibited by 3 individuals. In Study 2, we compared the effects of 2 NCR schedules in multielement designs, one with and the other without an extinction (EXT) component, while both schedules were thinned. Problem behavior remained low as the NCR schedule with EXT was thinned, but either (a) did not decrease initially or (b) subsequently increased as the NCR schedule without EXT was thinned. These results suggest that dense schedules of NCR decrease behavior by altering its motivating operation but that extinction occurs as the NCR schedule is thinned. The benefits and limitations of using dense or thin NCR schedules are discussed.     

THE DISPOSITIONALIST DEITY: HOW GOD CREATES LAWS AND WHY THEISTS SHOULD CARE

How does God govern the world? For many theists “laws of nature” play a vital role. But what are these laws, metaphysically speaking? I shall argue that laws of nature are not external to the objects they govern, but instead should be thought of as reducible to internal features of properties. Recent work in metaphysics and philosophy of science has revived a dispositionalist conception of nature, according to which nature is not passive, but active and dynamic. Disposition theorists see particulars as being internally powerful rather than being governed by external laws of nature, making external laws in effect ontologically otiose. I will argue that theists should prefer a dispositionalist ontology, since it leads them toward the theory of concurrentism in divine conservation, rather than occasionalism, and revives the distinction between internal and external teleology. God on this view does not govern the world through external laws of nature, but rather through internal aspects of powerful properties.     

Matching and maximizing with concurrent ratio-interval schedules.

Animals exposed to standard concurrent variable-ratio variable-interval schedules could maximize overall reinforcement rate if, in responding, they showed a strong response bias toward the variable-ratio schedule. Tests with the standard schedules have failed to find such a bias and have been widely cited as evidence against maximization as an explanation of animal choice behavior. However, those experiments were confounded in that the value of leisure (behavior other than the instrumental response) partially offsets the value of reinforcement. The present experiment provides another such test using a concurrent procedure in which the confounding effects of leisure were mostly eliminated while the critical aspects of the concurrent variable-ratio variable-interval contingency were maintained: Responding in one component advanced only its ratio schedule while responding in the other component advanced both ratio schedules. The bias toward the latter component predicted by maximization theory was found.     

Response rate, reinforcement frequency, and behavioral contrast

Pigeons responded for food on a multiple schedule in which periods of green-key illumination alternated with periods of red-key illumination. When behavior had stabilized with a variable-interval 2-min schedule of reinforcement operating during both stimuli, low rates of responding (interresponse times greater than 2 sec) were differentially reinforced during the green component. Conditions during the red stimulus were unchanged. Response rates during the green component fell without changing the frequency of reinforcement but there were no unequivocal contrast effects during the red stimulus. The frequency of reinforcement during the green component was then reduced by changing to a variable-interval 8-min schedule without reducing the response rates in that component, which were held at a low level by the spacing requirement. Again, the conditions during the red stimulus were unchanged but response rates during that stimulus increased. These results show that reductions in reinforcement frequency, independently of response rate, can produce interactions in multiple schedules.     

Further examination of factors that influence preference for positive versus negative reinforcement

Factors that influence choice between qualitatively different reinforcers (e.g., a food item or a break from work) are important to consider when arranging treatments for problem behavior. Previous findings indicate that children who engage in problem behavior maintained by escape from demands may choose a food item over the functional reinforcer during treatment (DeLeon, Neidert, Anders, & Rodriguez-Catter, 2001; Lalli et al., 1999). However, a number of variables may influence choice between concurrently available forms of reinforcement. An analogue for treatment situations in which positive reinforcement for compliance is in direct competition with negative reinforcement for problem behavior was used in the current study to evaluate several variables that may influence choice. Participants were 5 children who had been diagnosed with developmental disabilities and who engaged in problem behavior maintained by escape from demands. In the first phase, the effects of task preference and schedule of reinforcement on choice between a 30-s break and a high-preference food item were evaluated. The food item was preferred over the break, regardless of the preference level of the task or the reinforcement schedule, for all but 1 participant. In the second phase, the quality of the break was manipulated by combining escape with toys, attention, or both. Only 1 participant showed preference for the enriched break. In the third phase, choice of a medium- or low-preference food item versus the enriched break was evaluated. Three of 4 participants showed preference for the break over the less preferred food item. Results extend previous research by identifying some of the conditions under which individuals who engage in escape-maintained behavior will prefer a food reinforcer over the functional one.     

Reversed effects in closed and open economies

Pigeons received food according to either fixed-interval, fixed-ratio, or random-interval schedules in both closed and open feeding economies. In the closed economy, they were not food deprived, they controlled the amount of food received at each meal, and they had no other source of food. In the open economy, each feeding bout consisted of one feeder cycle, and the pigeons received supplemental feeding as needed to maintain them at 80% of their free-feeding weights. Response rate always increased with larger schedule requirements in the closed economy, but it either decreased steadily or increased and then decreased in the open economy. Initial pauses lengthened with longer fixed intervals or fixed ratios (FR) in the open economy but less so in the closed economy. Responding continued under FR 10,000 schedules in the closed economy, but never survived FR 400 in the open economy. In the open economy, fixed-interval schedules could maintain far more behavior than could either fixed ratios or random intervals. Familiar concepts such as matching and arousal can describe at least some of the behavior in the open economy, but current theory does not apply well to behavior in the closed economy. An explanation of economy-dependent effects might begin with the possibility that the two economies invoke different evolved survival strategies. These strategies influence behavior by means of different mechanisms and laws. The strategy for the closed economy may relate to weight conservation, but that for the open economy may be based on energy conservation.     

Resistance to change and preference for variable versus fixed response sequences

In Experiment 1, 4 pigeons were trained on a multiple chain schedule in which the initial link was a variable-interval (VI) 20-s schedule signalled by a red or green center key, and terminal links required four responses made to the left (L) and/or right (R) keys. In the REPEAT component, signalled by red keylights, only LRLR terminal-link response sequences were reinforced, while in the VARY component, signalled by green keylights, terminal-link response sequences were reinforced if they satisfied a variability criterion. The reinforcer rate for both components was equated by adjusting the reinforcer probability for correct REPEAT sequences across sessions. Results showed that initial- and terminal-link responding in the VARY component was generally more resistant to prefeeding, extinction, and response-independent food than responding in the REPEAT component. In Experiment 2, the REPEAT and VARY contingencies were arranged as terminal links of a concurrent chain and the relative reinforcer rate was manipulated across conditions. For all pigeons, initial-link response allocation was biased toward the alternative associated with the VARY terminal link. These results replicate previous reports that operant variation is more resistant to change than operant repetition (Doughty & Lattal, 2001), and show that variation is preferred to repetition with reinforcer-related variables controlled. Behavioral momentum theory (Nevin & Grace, 2000) predicts the covariation of preference and resistance to change in Experiments 1 and 2, but does not explain why these aspects of behavior should depend on contingencies that require repetition or variation.     

THE EFFECTS OF RESPONSE EFFICIENCY ON FUNCTIONALLY EQUIVALENT COMPETING BEHAVIORS

Three experiments addressed the role of response efficiency in the application of functional equivalence training. Functional equivalence training includes conducting a functional assessment of the problem behavior. Variables that predict and maintain the problem behavior are defined, and socially appropriate, functionally equivalent skills are identified and taught. The logic is that if the learner has a socially appropriate way to achieve the same function, he or she will be less likely to use problem behaviors. This study examined the role of response efficiency in functional equivalence training. Response efficiency was examined in terms of three variables: (a) physical effort, (b) schedule of reinforcement, and (c) the time delay between presentation of the discriminative stimulus and reinforcer delivery. Each of the three experiments involved a person who performed a set of problem behaviors and a functional assessment of the problem behaviors. A socially appropriate alternative response was taught, but this new response was less efficient than the problem behavior on one of the efficiency variables (effort, schedule, delay in time). The new behaviors did not compete successfully with the problem behaviors until a new, more efficient, alternative behavior was taught. These results are discussed in terms of our understanding of response covariation and the need in applied contexts to include response efficiency in any functional analysis assessment.     

The control of switching into blackout during extinction

During the extinction component of a multiple variable-interval extinction schedule, four pigeons learned to peck a second key that switched off the keylights. Two experiments attempted to isolate the events that control this behavior. In the first experiment, switching into blackout was equally maintained when switches were restricted to the first minute as when they were restricted to the last minute of the extinction component. When switches could be emitted in the first and last minutes, they occurred more frequently in the first. Restricting switching to the first minute of each component and eliminating the blackout between components had no effect on switching. In the second experiment, when the stimulus correlated with extinction was omitted, switching decreased slightly. Omission of both multiple schedule stimuli decreased the switching rate, but switching was still maintained. Food reinforcement was then omitted and switching by two birds increased. Switching ceased when blackout was no longer the consequence of pecking the switching key. It was concluded that switching was not controlled by the similarity of the blackouts produced by the switching key and those that occurred between components; nor was it maintained by the temporal proximity of switching responses to the onset of the reinforced component. Finally, switching did not appear to be controlled by the main-key stimuli correlated with the components of the multiple schedule.