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Individuals diagnosed with autism spectrum disorder (ASD) tend to display restricted, repetitive behaviors and deficits in social interaction. Rats exposed to valproate (VPA) in utero have been shown to model symptoms of ASD. In previous research, VPA rats engaged in less social interaction and more repetitive responding than controls. The purpose of the present study was to further investigate behavioral variability in the VPA rat model of ASD by testing VPA and control rats in a reinforced‐behavioral‐variability operant task. In this procedure, rats emitted sequences of lever presses, some of which produced food. During baseline, food was delivered probabilistically, and variability was not required. Next, rats were exposed either to a variability contingency, in which food was only delivered following sequences that differed sufficiently from previous sequences (i.e., variability required), or to a yoked contingency, in which variability was not required. We hypothesized that VPA rats would behave less variably than controls in this task. However, VPA and control rats responded similarly variably when variability was required. Furthermore, VPA rats behaved slightly more variably than controls during baseline and yoked conditions, when variability was not required. These findings contribute to the complex literature surrounding the VPA rat model of ASD. [ABSTRACT FROM AUTHOR]

Delay discounting is the loss in value of an outcome as a function of its delay. The present study focused on examining a trait‐like characteristic of delay discounting in a preclinical animal model. Specifically, we were interested in whether there was a positive relation between discounting of 2 different outcomes in rats. That is, would rats that discount delayed food steeply also discount delayed water steeply? In addition, we examined how session‐to‐session variability in discounting could be attributed to differences between subjects (trait variability) and to differences within subjects (state variability). Finally, we measured discounting from early‐ to mid‐adulthood, allowing us to examine changes in discounting as a function of age. Overall, we found a moderate, positive correlation between discounting of food and discounting of water in rats, providing further evidence that the relative consistency with which individuals discount different outcomes is a trait‐like characteristic. In addition, we found a high degree of within‐subject variability in discounting, indicating strong state‐like differences from session to session. Finally, overall, discounting decreased as a function of age; however, individual‐subject data showed variability in how discounting changed across time. Overall, our results show that differences in delay discounting between individuals reflect variability in both trait‐ and state‐like characteristics. [ABSTRACT FROM AUTHOR]

The present study examined resurgence of reinforced variability in college students, who completed a 3‐phase computer‐based variability task. In the first phase, baseline, points were delivered for drawing rectangles that sufficiently differed from previous rectangles in terms of a target dimension (size or location, counterbalanced) but were sufficiently similar in terms of the alternative dimension. In the second phase, alternative, points were only delivered for rectangles that were sufficiently different in terms of the alternative dimension, but repetitive in terms of the target dimension. In the third phase, extinction, no points were delivered. In baseline, participants made rectangles that were highly varied in terms of the target dimension and less varied in terms of the alternative dimension, and vice versa in the alternative phase. During extinction, levels of variability increased for the target dimension, providing evidence for resurgence of reinforced variability of a specific dimension of behavior. However, levels of variability also remained high for the alternative dimension, indicating that extinction‐induced response variability may also have impacted the results. Although future research is needed to explore other explanations, the results of this study replicate prior research with pigeons and provide some support for the notion of variability as an operant. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Relapse is the recovery of a previously suppressed response. Animal models have been useful in examining the mechanisms underlying relapse (e.g., reinstatement, renewal, reacquisition, resurgence). However, there are several challenges to analyzing relapse data using traditional approaches. For example, null hypothesis significance testing is commonly used to determine whether relapse has occurred. However, this method requires several a priori assumptions about the data, as well as a large sample size for between‐subjects comparisons or repeated testing for within‐subjects comparisons. Monte Carlo methods may represent an improved analytic technique, because these methods require no prior assumptions, permit smaller sample sizes, and can be tailored to account for all of the data from an experiment instead of some limited set. In the present study, we conducted reanalyses of three studies of relapse (Berry, Sweeney, & Odum, ; Galizio et al., ; Odum & Shahan,) using Monte Carlo techniques to determine if relapse occurred and if there were differences in rate of response based on relevant independent variables (such as group membership or schedule of reinforcement). These reanalyses supported the previous findings. Finally, we provide general recommendations for using Monte Carlo methods in studies of relapse. [ABSTRACT FROM AUTHOR]

The present study examined persistence and relapse of reinforced behavioral variability in pigeons. Pigeons emitted four‐response sequences across two keys. Sequences produced food according to a lag schedule, in which a response sequence was followed by food if it differed from a certain number of previous sequences. In Experiment 1, food was delivered for sequences that satisfied a lag schedule in both components of a multiple schedule. When reinforcement was removed for one component (i.e., extinction), levels of behavioral variability decreased for only that component. In Experiment 2, food was delivered for sequences satisfying a lag schedule in one component of a multiple schedule. In the other component, food was delivered at the same rate, but without the lag variability requirement (i.e., yoked). Following extinction, levels of behavioral variability returned to baseline for both components after response‐independent food delivery (i.e., reinstatement). In Experiment 3, one group of pigeons responded on a lag variability schedule, and the other group responded on a lag repetition schedule. For both groups, levels of behavioral variability increased when alternative reinforcement was suspended (i.e., resurgence). In each experiment, we observed some evidence for extinction‐induced response variability and for variability as an operant dimension of behavior. [ABSTRACT FROM AUTHOR]

Following training with verbal stimulus relations involving A is greater than B and B is greater than C, verbally-competent individuals reliably select A > C when asked “which is greater, A or C?” (i.e., verbal transitive inference). This result is easy to interpret. Nonhuman animals and humans with and without intellectual disabilities have been exposed to nonverbal transitive-inference procedures involving trained arbitrary stimulus relations. Following the training of A + B-, B + C-, C + D-, and D + E-, B reliably is selected over D (i.e., nonverbal transitive inference). Such findings are more challenging to interpret. The present research explored accounts of nonverbal transitive inference based in transitive inference per se, reinforcement, such as value-transfer theory, and operant stimulus control. In Experiment 1, college students selected B > G following the training of A + B-, B + C-, C + D-///E + F-, F + G-, and G + H- (where///signifies the omission of D + E-). In Experiment 2, college students selected B > G following the training of A + B-, B + C-, C + D-///E + F-, F + G-, and G + X- (where X refers to 10 stimuli that alternated across trials). In Experiment 3, college students selected G > B following the training of Y + B-, B + C-, C + D-///E + F-, F + G-, and G + X- (where Y and X refer to 10 stimuli, respectively, that alternated across trials). These findings are discussed in the context of operant stimulus control by offering an approach based in stimulus B typically acquiring only a select stimulus control topography. [ABSTRACT FROM AUTHOR]

There is disagreement about how to characterize the environment-behavior relations involved in the reinforcement of behavioral variability. The present research examined some of these issues using food-maintained, 4-peck sequences in pigeons. Experiment 1 evaluated the claim that behavioral variability is not reinforced directly but, rather, is the byproduct of changing over within sequences. Considerably higher levels of behavioral variation occurred under a relative-frequency threshold contingency than under a contingency that required a changeover but not variability per se. These results are consistent with the argument that behavioral variability is reinforced directly. Experiment 2 assessed the effects on variation levels of manipulating inter-trial and inter-response intervals. Variability increased with longer inter-response intervals but not with longer inter-trial intervals. These results are consistent with multiple explanations, including the notion that remembering past behavior interferes with the emission of reinforced variation. Consequently, Experiment 3 examined more directly the relation between remembering and reinforced variation. Variation levels were not affected by a concurrent contingency that encouraged pigeons to remember their past behavior. The implications of this research are presented in the context of working towards an understanding of the environment-behavior relations involved in the reinforcement of behavioral variability. [ABSTRACT FROM AUTHOR]

Delay discounting is the process by which a commodity loses value as the delay to its receipt increases. Rapid discounting predicts various maladaptive behaviors including tobacco use. Typically, delay discounting of different outcomes has been compared between cigarette smokers and nonsmokers. To better understand the relationship of delay discounting to different modes of tobacco use, we examined the differences in delay discounting of different outcomes between cigarette smokers, smokeless tobacco users, e‐cigarette users, and non‐tobacco users. In the present study, all participants completed 8 titrating delay‐discounting tasks: $100 gain, $500 gain, $500 loss, alcohol, entertainment, food, a temporary health gain, and a temporary cure from a disease. Non‐tobacco users discounted most outcomes less than tobacco users overall; however, there were no differences in discounting among the different types of tobacco users. These results suggest that nicotine consumption of any kind is associated with a higher degree of impulsivity compared to non‐tobacco users. Adoption of tobacco products that have been perceived as less harmful (e.g., e‐cigarettes) is not associated with a baseline difference or decrease in delay discounting if adopted after a history of cigarette use. [ABSTRACT FROM AUTHOR]

Steep delay discounting is characterized by a preference for small immediate outcomes relative to larger delayed outcomes and is predictive of drug abuse, risky sexual behaviors, and other maladaptive behaviors. Nancy M. Petry was a pioneer in delay discounting research who demonstrated that people discount delayed monetary gains less steeply than they discount substances with abuse liability. Subsequent research found steep discounting for not only drugs, but other nonmonetary outcomes such as food, sex, and health. In this systematic review, we evaluate the hypotheses proposed to explain differences in discounting as a function of the type of outcome and explore the trait‐ and state‐like nature of delay discounting. We found overwhelming evidence for the state‐like quality of delay discounting: Consistent with Petry and others' work, nonmonetary outcomes are discounted more steeply than monetary outcomes. We propose two hypotheses that together may account for this effect: Decreasing Future Preference and Decreasing Future Worth. We also found clear evidence that delay discounting has trait‐like qualities: People who steeply discount monetary outcomes steeply discount nonmonetary outcomes as well. The implication is that changing delay discounting for one outcome could change discounting for other outcomes. [ABSTRACT FROM AUTHOR]

We examined the effects of outcome framing on delay discounting. In Experiment 1, participants completed four delay‐discounting tasks. In one monetary task, money was framed in units of dollars (＄50), and in the other, money was framed in units of handfuls of quarters (equal to ＄50). In one food task, food was framed in clear units of food (e.g., 100 M&Ms), and in the other, food was framed in units of servings (e.g., 10 servings of M&Ms). When money was framed in units of dollars, participants discounted less by delay compared to discounting of handfuls of quarters. When food was framed as clear units, participants also discounted less compared to how they discounted servings. In Experiment 2, participants completed two delay‐discounting tasks for dollars and quarters (e.g., ＄50 or 200 quarters) to determine if the results of Experiment 1 were due to the differences in handling costs. In one delay‐discounting task, money was framed in units of dollars. In the other delay‐discounting task, money was framed in units of quarters. There was no difference in how participants discounted delayed money framed as dollars or quarters. Clear unit framing may result in less discounting by delay than fuzzy unit framing. [ABSTRACT FROM AUTHOR]

Alcohol is the most commonly used drug in the United States and alcohol abuse can lead to alcohol use disorder. Alcohol use disorder is a persistent condition and relapse rates following successful remission are high. Many factors have been associated with relapse for alcohol use disorder, but identification of these factors has not been well translated into preventative utility. One potentially important factor, concurrent nicotine use, has not been well investigated as a causal factor in relapse for alcohol use disorder. Nicotine increases the value of other stimuli in the environment and may increase the value of alcohol. If nicotine increases the value of alcohol, then nicotine use during and after treatment may make relapse more probable. In the current study, we investigated the effect of continuous nicotine exposure (using osmotic minipumps to deliver nicotine or saline, depending on group, at a constant rate for 28 days) on resurgence of alcohol seeking in rats. Resurgence is a type of relapse preparation that consists of three phases: Baseline, Alternative Reinforcement, and Resurgence Testing. During Baseline, target responses produced a dipper of alcohol. During Alternative Reinforcement, target responses were extinguished and responses on a chain produced a chocolate pellet. During Resurgence Testing, responses on the chain were also extinguished and a return to responding on the target lever was indicative of resurgence. Multilevel modeling was used to analyze the effect of nicotine on resurgence. Both the nicotine and saline group showed resurgence of alcohol seeking, but there was no difference in the degree of resurgence across groups. Future directions could involve testing alternative drug delivery techniques. [ABSTRACT FROM AUTHOR]