Search

Reinforcement learning occurs when organisms adapt the propensities of given behaviours on the basis of associations with reward and punishment. Currently, reinforcement learning models have been validated in minimalist environments in which only 1-2 environmental stimuli are present as possible predictors of reward. The exception to this is two studies in which the responses of the dopamine system to configurations of multiple stimuli were investigated, however, in both cases the stimuli were presented simultaneously rather than in a sequence. Therefore, we set out to understand how current models of reinforcement learning would respond under more complex conditions in which sequences of events are predictors of reward. In the two experimental chapters of this thesis, we attempted to understand whether midbrain dopaminergic neurons would respond to occasion setters (Chapter 3), and to the overexpectation effect (Chapter 4). In addition, we ran simulations of the behavioural paradigms using temporal difference models of reinforcement learning (Chapter 2) and compared the predictions of the model with the behavioural and neurophysiological data. In Chapter 3, by performing single-neuron recording from VTA and SNpc dopaminergic cells, we demonstrated that our population of neurons were most responsive to the latest predictor of reward, the conditioned stimulus (CS) and not the earliest, the occasion setter (the OS). This is in stark contrast with the predictions of the model (Chapter 2), where the greatest response is seen at the OS onset. We also showed at a neural level that there was only a weak enhancement of the response to the discriminative stimulus (SD) when this was preceded by the OS. On the other hand, at a behavioural level, bar pressing was greatest when the SD was preceded by the OS, demonstrating that rats could use the information provided by the OS, but that dopamine was not controlling the conditioned response. In Chapter 4, our population of dopaminergic neurons showed that they would preferentially respond to only one of the two conditioned stimuli (CSA, CSB) in the overexpectation paradigm. The predictions of the model (Chapter 2) suggested that when the two stimuli would be presented in compound, there would be an inhibitory response if the reward magnitude was kept constant and an excitatory response if the reward magnitude was doubled. The lack of neural firing to one of the two conditioned stimuli, however, does not make for easy interpretation of the data. Perhaps, one of the conditioned stimuli acted as if it were overshadowing the other, resulting in no response to the second CS. Interestingly, at a behavioural level, we did not see increased licking frequency to the compound stimuli presentation, a result that is somewhat at odds with the previous literature. Overall, the results of our experimental chapters suggest that the role that midbrain dopaminergic neurons play in reinforcement learning is more complex than that envisaged by previous investigations.

After a discussion of the behaviours that are found to occur under various common schedules of reinforcement, a mathematical model of learning is proposed, which covers those schedules where reinforcement can be prescribed, as a function of the time between successive responses. There are several possible conceptualisations of the model. The one considered most often is one that uses the basic notions of Stimulus Sampling Theory. The predictions of the model are tested against the known properties of ratio, interval and DR1 schedules of reinforcement. In only one case do the predictions of the model run counter to accepted experimental fact. The model is also tested against specific data from human subjects on ratio, interval, and DRL schedules. The model fits well to the asymptotic interresponse time distributions for these schedules. However the fit of the model to distributions conditional on the previous response being reinforced, or the previous response not being reinforced, range from good to very bad, suggesting that sequential effects are more complex than implied by the model.

Behavior-specific praise has been shown to increase rate of desired behaviors for individuals with intellectual and developmental disabilities, though it is rarely used by caregivers in residential facilities for adults with disabilities. Prompting in the form of tactile stimulation has been demonstrated to increase rate of behavior-specific praise delivered by teachers and caregivers. The purpose of the current study was to increase the quantity and quality of behavior-specific praise statements that were delivered by caregivers to individuals at a large residential facility for adults with disabilities. A tactile prompting device (Gymboss Interval Timer and Stopwatch) was provided to the caregivers and set to vibrate for one second at intervals of five minutes, for a total of six intervals. Instructions were provided to the caregivers to deliver behavior-specific praise statements, for appropriate behaviors, to their assigned clients every time a vibration occurred. Examples of behavior-specific praise statements were provided to the caregivers before each session, but no feedback was delivered during the prompting phase. Results indicated that a tactile prompting device was effective at increasing rate of behavior-specific praise statements delivered by caregivers in as little as one session.

Falk's pivotal 1961 study showed that rats would drink excessive amounts of water when exposed to a time based schedule of reinforcement. Since then, schedule-induced drinking or polydipsia, has been demonstrated with several species and with a variety of different behaviors. Rats, the most commonly used animal, have been shown to drink excessive amounts of water under a variety of different time based schedules of reinforcement; exclusively during a free operant procedure. The current study shows that water drinking can be induced during a discrete trial procedure, and instead of using a time-based schedule of reinforcement, this study used a variable-ratio schedule of reinforcement. The results showed that excessive water drinking was induced under these conditions with a canine.

Positive and negative reinforcement contingencies have been compared in terms of preference, but the differential effects of positive and negative reinforcement on reaction time and accuracy with other variables controlled remain unclear. Fifteen undergraduate students participated in a sound discrimination task that involved random mixed-trial presentations of positive and negative reinforcement contingencies. The participants' goal was to correctly identify whether the tone was shorter or longer than 600 milliseconds. On positive reinforcement trials, the participants received feedback and money tallies only if they identified the sound length correctly, with each correct response in the positive reinforcement trials earning the participant 10 cents. On negative reinforcement trials, the participants received feedback and money tallies only if they identified the sound length incorrectly, with incorrect trials subtracting 10 cents from the participants' total money (which began at $4.00 to equalize the weights of the positive and negative reinforcement contingencies). Accuracy analyses showed a relatively curvilinear relationship between the number of errors for each participant and the binned duration of the sound stimulus, with no differences across the positive and negative reinforcement conditions. Results also indicated weak linear negative correlations at the single subject level between comparison stimulus duration and reaction time, with similar slopes between positive and negative reinforcement trials, and strong curvilinear correlations at the group level, indicating differences between grouped and individual analyses. Overall our results appear to support abandoning the distinction between positive and negative reinforcement as two separate behavioral processes.

Behavioral skills training (BST) is often used to train caregivers to implement various behavior management procedures; however, additional strategies are sometimes required to promote the generalization of skills from a contrived setting to the natural environment. Generalizing skills to the natural environment requires that the caregiver's behavior transfer from control of stimuli in the contrived setting to stimuli in the natural environment, and the skill continues to be performed with high levels of accuracy. The purpose of this study was to assess the extent to which caregivers generalized the use of social reinforcement, in the form of descriptive praise, from the contrived setting to the natural environment. When caregivers failed to respond to opportunities, a progressive prompt delay was used to bring caregivers' responding under the control of relevant client behavior; feedback was used to improve the accuracy with which caregivers implemented reinforcement. Five caregivers in a large residential facility participated in the study; single-opportunity probes were used to assess caregiver's identification of opportunities and accuracy in implementing reinforcement for two defined client behaviors, compliance and appropriate attention-getting behavior. Results of the study suggest that skills failed to generalize from the contrived setting to the natural environment. However, prompting was effective in training caregivers to identify opportunities to provide reinforcement, and feedback improved implementation of reinforcement.

The differential outcomes effect (DOE) refers to an observed increase in rates of acquisition of simple or conditional relations when the contingencies of reinforcement arrange for reinforcers to be uniquely correlated with a particular stimulus or response relative to conditions where the reinforcers are not uniquely correlated with either stimulus or response. This effect has been robustly documented in the literature with nonhuman subjects. This study asked whether the DOE would be observed with children with autism spectrum disorder (ASD) learning audio-visual conditional relations. Two participants learned two sets of 3 audio-visual conditional relations. For one set, the training conditions arranged for each of the three conditional relations to be uniquely correlated with a particular reinforcing stimulus (the DO condition). For the second set, the training conditions arranged for the same reinforcer to be used for all three audio-visual conditional relations (the NDO condition). Early results show that audio-visual conditional relations were acquired faster under the DO condition relative to the NDO outcomes condition (accuracy in DO condition was 30.8% higher on average than in NDO condition). These data suggest that differential outcomes should be more thoroughly investigated with children with diagnoses of ASD.

Bipolar disorder is characterized by disruptions in mood and affect that occur not only during mood episodes, but during euthymic periods as well. At the same time, sensitivity of the behavioral activation system (BAS) has been implicated in the disorder and is a risk marker for it. Less clear is the relationship between BAS sensitivity and positive affect, particularly lower level facets of positive affect. The aim of the present study was to examine the relationship between positive affect and vulnerability for mania as assessed using BAS sensitivity. Specifically, the link between daily levels and fluctuations of positive affect and baseline BAS sensitivity was examined. Following the hierarchical model of affect, this study also assessed the relationship between BAS sensitivity and the distinct facets of positive affect. Finally, this study examined whether BAS sensitivity moderates associations between daily rewards and positive affect. Undergraduates (N = 265) from a large university in the South were recruited to complete measures of BAS sensitivity, affect, and mood symptoms at baseline. Using ecological momentary assessment (EMA), participants completed daily surveys assessing affect and engagement with rewarding situations. An exploratory factory analysis revealed a four factor structure of positive affect, consisting of Serenity, Joviality, Attentiveness, and Self-Assurance. Greater daily levels of overall positive affect, as well as the lower order facets of Joviality, Self-Assurance, and Attentiveness, were predicted by heightened BAS sensitivity. In contrast, the facet of Serenity demonstrated minimal associations with BAS sensitivity. The study findings support a multi-faceted structure of positive affect and suggest that certain facets may be more closely related to risk for bipolar disorder. Specifically, Joviality and Self-Assurance may represent maladaptive forms of positive affect, whereas Serenity may function as a protective element against bipolar disorder.

Observational learning (OL) occurs when an individual contacts reinforcement as a direct result of discriminating the observed consequences of other individuals' responses. Individuals with autism spectrum disorder (ASD) may have deficits in observational learning and previous research has demonstrated that teaching a series of prerequisite skills (i.e., attending, imitation, delayed imitation, and consequence discrimination) can result in observational learning. We sequentially taught these prerequisite skills for three young children with ASD across three play-based tasks. We assessed the direct and indirect effects of training by assessing OL before and after instruction across tasks and task variations (for two participants) during both in-vivo and video-model probes using a concurrent multiple-probe design. All participants acquired the prerequisite skills and demonstrated observational learning during probes of directly-trained tasks. Generalization results varied across participants. Observational learning generalized to one untrained task for one participant. For the other two participants, observational learning generalized to variations of the trained tasks but not to untrained tasks. Generalization additionally occurred during the in-vivo probes for both participants for whom we assessed this response. Implications of these findings, as well as directions for future research, are discussed.

Operant response rate can be viewed as bouts, periods of alternating engagement and disengagement with ongoing schedules of reinforcement. Relatively few studies have examined the role of force and effort on engagement bouts. Moreover, those examining effort have used switch closure devices to define the response. Switch closures tend to overestimate the effect of effort because increasing the force requirement excludes low-force responses that previously activated the switch. In the present study, we examined the effects of effort using a force transducer, which allows us to record criterion responses that meet the force requirement and subcriterion responses that do not. The current study was conducted using four male Sprague Dawley rats. Each rat was run through a series of four conditions, each with a different combination of variable interval schedules (VI 30s, VI 120s) and force requirements (5.6g, 32g). Log survivor analyses of bout structure showed that increased force requirements decreased the rate of bout initiations. Additionally, when log-survivor functions were computed using only criterion responses, shifts in the function were less extreme than when all measured responses were used; the latter finding suggests exclusion of "subcriterion" responses in prior work has overestimated the effects of force on bout structure

Behaving in novel ways is essential to the development of the types of complex performances described by the term creativity, problem solving, and perseverance. Some research suggests that response variability is an operant and a critical component of novel behavior. However, other account of novel behavior may be more parsimonious. Topographical variability has rarely been examined, nor has operant variability with organisms with baselines featuring stereotypic responding. This study examined the effects of a variability-specifying contingency on the cumulative novel responses of undergraduate students. Using the PORTL apparatus, participants interacted with a ball with a single hand. When the variability-specifying contingency was in effect, novel topographies were reinforced. When a reinforce every response condition was implemented, the participants did not emit any novel responses. When variability-specifying contingencies were in effect, novel responses were rarely followed by subsequent novel responses. They were mostly followed by repeated emission of the same topography, or by other previously emitted topographies. Novel responding did not persist long, although the variability-specifying contingency remained in effect and the potential for novel responding was great. The variability-specifying contingency often resulted in stereotypic response chains. Each of these findings call into the question the assertion that variability is an operant and suggests other possible explanations for the observed novelty.

Behavioral momentum theory (BMT) has become a prominent method of studying the effects of reinforcement on operant behavior. BMT represents a departure from the Skinnerian tradition in that it identifies the strength of responding with its resistance to change. Like in many other operant research paradigms, however, responses are considered to be momentary phenomena and so little attention has been paid to non-rate dimensions of responding. The current study takes up the question of whether or not the degree of effort defining a discriminated operant class has any meaningful effect on its resistance to change. Using a force transducer, rats responded on a two-component multiple VI 60-s VI 60-s schedule where each component was correlated with a different force requirement. Resistance to change was tested through prefeeding and extinction. Proportional declines in response rate were equal across components during all disruption tests. Differentiated response classes remained intact throughout. The negative result suggests several future research directions.

Reinforcer assessments have largely relied on the use of progressive ratio (PR) schedules to identify stimuli that function as reinforcers. PR schedules evaluate the reinforcing efficacy of a stimulus by measuring the number of responses produced in order to access a stimulus as the number of required responses increases. The current evaluation extends the literature on reinforcer assessments by measuring responding under a progressive force (PF) schedule, in addition to progressive ratio requirements. We compared responding under PR and PF schedules with two children with autism using a multielement design embedded within a reversal experimental design. Results were mixed and implications for further development of reinforcer assessment methods (particularly PF schedules) are discussed.

Sidman's (2000) theory of stimulus equivalence predicts an interaction between the development of analytic units and the development of equivalence relations. Previous research has documented these interactions (stewart, Barnes-Holmes, Roche, & Smeets, 2002; Vaidya & Brackney, 2014), therefore the current study attempted to replicate the effects seen in Vaidya & Brackney, 2014 (Experiment 2). Baseline conditional discriminations were trained for two sets of three, three-member classes, while participants simply observed stimuli in the third set which was arranged identical to those of Sets 1 and 2. Following equivalence tests where performance met the accuracy criterion of 85% for Sets 1 and 2, participants then entered a simple successive discrimination training phase where common responses were then trained with an equivalence class (pressing the Q key in the presence of A1, B1, or C1), cross equivalence classes (pressing the R key in the presence of A4, A5, or A6), or for stimuli where the participants had experience with them, but the contingencies were never arranged to facilitate equivalence class formation. Results showed a facilitative effect for common responses drawn from within equivalence classes (Set 1), and a retardation effect for common responses drawn from across equivalence classes (Set 2), for three of the five participants. Results for Set 3 showed an acquisition that fell intermediate to that of Sets 1 and 2, respectively, suggesting an interaction occurring between existing equivalence relations and the development of analytic units.

Community exercise can offer many benefits for children, including the opportunity to engage in physical activity and interact with peers in a social setting. Children with autism do not engage in as many community activities as their typical peers. This study examines conditions to teach young children to complete yoga poses to mastery. The effects of prompting, programmed reinforcers, and a chaining criteria were evaluated using a comparison design with two baselines and one intervention condition, replicated across two children with autism. Both children mastered performance of all four targeted yoga poses. The findings are discussed in the context of previous research on the benefits of yoga.

This study compared the relative reinforcing efficacy of high-preferred and low-preferred stimuli, as determined by two types of preference assessments, on acquisition rates in three children diagnosed with an Autism Spectrum Disorder (ASD). The study also evaluated the indirect effects of preference on students’ stereotypy and problem behavior during instructional periods. Participants were presented with a task and provided high or low-preferred stimuli contingent upon correct responding. Results showed that acquisition occurred more rapidly in the highly preferred condition for some participants. Higher rates of problem behavior occurred in the low preferred condition for all participants. These results highlight the importance of utilizing preference assessment procedures to identify and deliver high-preferred items in skill acquisition procedures for individuals with ASD.

Stimulus preference assessments have determined high and low preferred items that increase the rate of frequency of responding for various skills. Within applied settings, high preferred items may not attain the same reinforcing value across tasks which might decrease responding. The preference of the task might have an effect on reinforcer efficacy that is being presented. The purpose of the current study is to evaluate changes in reinforcer efficacy as a function of preference for the task. Three children diagnosed with ASD participated in the study. HP/LP items and HP/LP tasks were identified through paired-choice assessments, and each item was presented as a consequence for each task in a counterbalanced multi-element format. Results indicated that preference for the task had little effect of the rate of responding across items.

Although response effort is considered a dimension of the cost to obtain reinforcement, little research has examined the economic impact of effort on demand for food. The goal of the present study was to explore the relationship between effort and demand. Three Sprague Dawley rats were trained to press a force transducer under a series of fixed-ratio schedules (1, 10, 18, 32, 56, 100, 180, 320, and 560) under different force requirements (5.6 g and 56 g). Thus, nominal unit price (responses / food) remained constant while minimal response force requirements varied. Using a force transducer allowed the measurement of responses failing to meet the minimal force requirement (i.e. “subcriterion responses”), an advantage over prior approaches using weighted levers to manipulate effort. Consistent with prior research, increasing the unit price decreased food consumption, and raising minimum force requirements further reduced demand for food. Additionally, increasing the force requirement produced subcriterion responses. Analysis indicated that subcriterion responses did not create incidental changes in unit price. Obtained force data revealed that including obtained forces in unit price calculations provided better predictions of consumption when compared to using criterion force requirements.

Many researchers have devoted attention to the human tendency to find coherence or make sense of events in the environment. Until recently, however, there was no direct empirical evidence that making sense could function as a reinforcer. Wray, Dougher, and Bullard (2008) provided preliminary evidence that solvable conditions are preferred over unsolvable conditions indicating that making sense is reinforcing. Results from the current study replicate these findings with two additional behavioral measures. Results further indicate that both solvable and neutral conditions are preferable to unsolvable conditions. However, results show there is little difference in preference for solvable over neutral conditions. All findings held across both concurrent and forced choice procedures. Results suggest that avoiding conditions that cannot be solved is negatively reinforcing, and that, for some participants, engaging in sense-making is positively reinforcing. This evidence suggests that it may be useful to define making sense functionally, as two distinct behaviors, according to whether it is being maintained by positive versus negative reinforcement.

This experimental study aimed to show the motivational effect of mood-altering verbal events on consequential functions through use of a within-subjects, repeated-measures design. Specifically, the effects of mood-induction on the self-reported value of various activities were investigated using explicit and implicit measurement. The Implicit Relational Assessment Procedure (IRAP) was used as an indirect measure of changes in the reinforcing value of pleasant and unpleasant cognitive activities after mood induction. Implicit assessment allowed for minimization of demand characteristics together with assessment of cognitive preferences that participants were unaware of or reluctant to report. Data from 30 university undergraduates were analyzed and predicted effects regarding the differential reinforcement value of pleasant and unpleasant overt and covert activities after positive and negative mood induction were demonstrated. Pleasant activities were more reinforcing after positive mood induction and less reinforcing after negative mood induction, when unpleasant activities increased in reinforcing value. Interestingly, participants explicit report of mood state was often incongruent with their explicit and implicit preferences for overt and covert activities. Specifically, many participants did not explicitly report a negative affective state after negative mood-induction procedures, but they nonetheless preferred pleasant activities less. The reinforcing value of pleasant and unpleasant activities changed regardless of the mood state reported, based on contact with verbal environmental events. Altogether, these findings support the claim that verbal mood-altering antecedent events can function to alter the reinforcing value of activities, thus contributing to existing evidence that they function as motivating operations. Additionally, this study underscores the importance of implicit assessment, and highlights the potential utility of the IRAP as a clinical tool.

The purpose of the current study was to examine the effects of using fixed time schedules with different magnitudes of stimulus delivery as treatment for pica. A functional assessment was conducted, which indicated that pica occurred across experimental conditions and was most frequent in the absence of social stimulation or contingencies. A competing stimulus assessment was then conducted to identify stimuli that could potentially compete with pica during NCR. Subsequently, an evaluation of the effects of reinforcer magnitude on NCR as a treatment of pica was conducted. Treatment results indicated that quantity of reinforcer increased the effectiveness of leaner schedules of reinforcer delivery; however, it was not possible to fade the temporal schedule to one that would have been useful in practice. In addition, limitations and future research are outlined.

A choice paradigm was used to evaluate allocation of interlocking behavior of two groups of two participants between responses having operant consequences only and responses having cultural consequences. In a discrete trial BABABAB design, each participant could select one of three options, which delivered either 3 or 5 points. In B (cultural consequence) conditions, two of the options had additional effects: the 3-point option also added 3 points to the other participant's earnings, and one of the 5-point options also subtracted 5 points from the other participant's earnings. The third option was unchanged in both conditions and delivered 5 points to the participant who selected it. Results indicated that participants in both groups initially frequently produced response combinations that earned 8 points for one or the other individual (and 0 or 3 points for the other), but allocation of responding increasingly changed to combinations that produced 6 points for each individual. This shift in performances away from maximum individual reinforcement towards maximum group reinforcement indicates cultural contingencies did not act in concert with operant contingencies, suggesting they are different mechanisms of selection.

The current study investigated the impact of delivering a jackpot on response rate and response allocation in two domestic dogs. For the purpose of this research, a jackpot was defined as a one-time, within-session increase in the magnitude of reinforcement. Two experiments were conducted to investigate the effects of delivering a jackpot in both single-operant and concurrent schedule procedures. Experiment 1 investigated the impact of a one-time, within-session increase in the magnitude of reinforcement on response rate in a single-operant procedure. Results of Experiment 1 showed no clear change in response rate after the delivery of the jackpot. Experiment 2 investigated the impact of a one-time, within-session increase in the magnitude of reinforcement on response allocation in a concurrent schedule procedure. Results of Experiment 2 showed an increase in response allocation to the jackpotted contingency in both subjects. These results suggest that a jackpot, as defined here, has no effect in single-operant procedures while having an effect in concurrent schedule procedures. These effects are similar to those reported in the magnitude of reinforcement literature.

Social stimuli that function as reinforcers for most children generally do not function as reinforcers for children diagnosed with autism. These important social stimuli include smiles, head nods, thumb-ups, and okay signs. It should be an important goal of therapy for children with autism to condition these neutral social stimuli to function as reinforcers for children diagnosed with autism. There is empirical evidence to support both a pairing procedure (classical conditioning) and a discriminative stimulus procedure to condition neutral stimuli to function as reinforcers. However, there is no clear evidence as to the superiority of effectiveness for either procedure. Despite this most textbooks and curriculum guides for children with autism state only the pairing procedure to condition neutral stimuli to function as reinforcers. Recent studies suggest that the discriminative stimulus procedure may in fact be more effective in conditioning neutral stimuli to function as reinforcers for children diagnosed with autism. The present research is a further comparison of these two procedures. Results from one participant support recent findings that suggest the discriminative stimulus procedure is more effective in conditioning neutral stimuli to function as reinforcers. But the results from the other participant show no effects from either procedure, suggesting future research into conditions necessary to condition neutral social stimuli to function as reinforcers for children with autism.

The purpose of the current study was to investigate the immediate and subsequent effects of fixed-time attention on problem behavior maintained by therapist attention utilizing a three-component multiple-schedule design. The treatment analysis indicated that fixed-time attention produced a significant immediate decrease in the frequency of physically disruptive behavior (PDB), represented by low frequencies of PDB in Component 2, as well as a continued subsequent effect, represented by lower frequencies of problem behavior in Component 3 when compared to Component 1. The possible behavioral mechanisms responsible for the observed suppression in Component 2 of the treatment analysis are discussed. Evidence of behavioral contrast was observed in Components 1 and 3 of the treatment analysis in conditions in which Component 2 contained a fixed-time schedule of stimulus delivery. In addition, limitations and future research are outlined.

Pigeons worked in a titrating delay match-to-sample (TDMTS) procedure in which selecting the correct comparison stimulus increased the delay between sample offset and comparison-array onset and incorrect comparison selections decreased that delay. Prior research in our lab has shown that the stable adjusted value of the retention interval is a curvilinear function of the observing response requirement. The current study examined the effect of the distribution and predictability of observing response requirements on adjusted retention interval values. The data show that unpredictable observing response requirements were more effective in attenuating the deleterious effects of delay on matching accuracy. The data have implications for our understanding of attending and encoding in performances involving remembering over short temporal durations.

The current study consisted of two experiments, both of which were comparisons of choice conditions replicated across four participants. Four typically-developing pre-school children participated in this study. Experiment 1 evaluated participants' preference for choosing consequent stimuli prior to engaging in academic tasks (pre-session choice) versus choosing consequent stimuli each time criterion for reinforcement had been met within the session (within-session choice). In Experiment 2, preference for choice-making was evaluated when outcomes for both choice and no-choice conditions were identical. For two participants, results indicated strong preference for choice-making.

The immediate and subsequent effects of response-independent food delivery on problem behavior maintained by food were investigated. A functional analysis indicated that the participant's problem behavior was maintained by tangible (food) reinforcement. In a subsequent analysis, each occurrence of problem behavior produced a bite of wafer in the first and third components of mixed and multiple schedules, while either response-independent food or extinction was presented in the second component. Dense and lean schedules of food delivery were assessed. Results indicated that a very dense schedule of food nearly eliminated problem behavior, a very lean schedule of food and extinction produced substantial decreases in problem behavior, and intermediate schedules did not decrease problem behavior. Response patterns were differentiated across mixed and multiple schedule arrangements, with signaled changes in the schedules (multiple schedule) generally showing more immediate and sustained effects throughout the intervention component. Implications for interpretations of the effects of the intervention are discussed.

Aggression in dogs is a significant public health concern with 7.2 mortality cases per 100 million inhabitants and approximately 4.7 million dog bites annually. Canine aggression is typically viewed as a genetic trait and treated as pathology through the use of medical or respondent behavioral procedures. In this study the effects of the differential negative reinforcement of safe, alternative behaviors to aggression using distancing as the reinforcer were evaluated. The results demonstrated that even when the aggression was in evidence throughout most of the dog's lifetime, it responded quickly to changes in reinforcement contingencies.

A variable that may be associated with performance improvements is goal setting (within and across days). Easy-to-achieve goals will likely produce gradual trends in improvement and difficult-to-achieve goals steeper trends. The purpose of the current experiments was to study the effects of setting easy-to-achieve and difficult-to-achieve goals on the level, trend, and variability of correct, incorrect, and skip responses for math tasks when reinforcement contingencies and numbers of practices were held constant. Five undergraduate students answered math problems on flash cards in 30s timings. Single case design elements were used to evaluate the effects of different types of goals on the speed and accuracy of performance. The results revealed that goal setting primarily increased the frequency of incorrect responses and both the level and trend of skip responses. The implications of these findings and other important variables that influence the effectiveness of goal setting are discussed. In addition, the authors suggest guidelines to follow when implementing goals to improve performance.

The research investigated the impact of sexual harassment on withdrawal behaviors and attitudes toward harassment by examining the gender composition of the harassment dyad and the organizational status of the perpetrator in relation to the victim. Archival data from the Inter-University Consortium for Political and Social Research at the University of Michigan was used to obtain surveys in which participants rated their attitudes and experiences related to sexual harassment. Only individuals who reported experiencing sexual harassment within the 24 months prior to data collection are included in the current research. A MANOVA was conducted to determine if withdrawal behaviors and attitudes of victims varied by the gender dyad and/or the organizational status of the perpetrator. Results indicated that individuals harassed by people with higher organizational status displayed more withdrawal behaviors in the form of decreased productivity and increased use of sick, annual, and unpaid leave. Individuals harassed by a member of the same gender also used more unpaid leave. Interestingly, individuals harassed by members of the opposite gender, tended to disagree more strongly with the attitude index measuring cautious awareness of sexual harassment.

This study evaluated the effects of programming a variability contingency on one object and the generalization of variability across other objects and contingencies when the defining features of the variable responses were topographical differences. A dog's interactions with five different objects were measured under both ANY (where any physical contact with the object would be reinforced on a fixed ratio schedule) and the VAR contingencies (where only the novel responses per trial would be reinforced). The ANY contingency produced stereotyped responding of behavior with all objects. When one of the dog-object interactions was changed to the VAR contingency, a marked decrease in stereotypic behavior and an increase in novel responses in the form of topographical combinations were observed across both contingencies.

There is disagreement among clicker trainers on whether or not food should be delivered every time the clicker (conditioned reinforcer) is used. However, presenting a conditioned reinforcer without food can weaken the strength of the conditioned reinforcer and also disrupt its discriminative stimulus function. A within subjects reversal design was used with 2 dogs to compare the behavioral effects of continuous pairings (C+F condition) vs. intermittent pairings (C+C+F condition) of the clicker with food. Results show that the C+C+F condition affects the frequency, accuracy, topography, and intensity of the behavior, and increases noncompliance and other unwanted behaviors. This study adds to the literature by evaluating the effects of conditioned reinforcement in an applied setting using discrete trials without undergoing extinction.

The purpose of this experiment was to compare the effects of combining negative reinforcement and positive reinforcement during teaching with the effects of using positive reinforcement alone. A behavior was trained under two stimulus conditions and procedures. One method involved presenting the cue ven and reinforcing successive approximations to the target behavior. The other method involved presenting the cue punir, physically prompting the target behavior by pulling the leash, and delivering a reinforcer. Three other behaviors were trained using the two cues contingent on their occurrence. The results suggest that stimuli associated with both a positive reinforcer and an aversive stimulus produce a different dynamic than a situation that uses positive reinforcement or punishment alone.

We evaluated behavior exhibited by individuals with developmental disabilities using progressive ratio schedules. High- and low-preferred stimuli were determined based on the results of a paired-stimulus preference assessment and were evaluated in subsequent reinforcer and progressive ratio assessments using concurrent- and single-operant schedules of presentation in a modified reversal design. Results showed that for two participants, stimuli determined to be low-preferred via a preference assessment functioned as reinforcers when evaluated independently of high-preferred stimuli and under gradually increasing response requirements. The results suggest that for cases in which a high-preferred stimulus is unavailable or unfeasible, the contingent delivery of relatively less-preferred stimuli may maintain appropriate behavior, even as response effort is increased. In addition, results of the progressive ratio evaluation are suggestive of stimulus value.

Preference for single versus varied reinforcers was assessed in the context of a token system. This study also assessed the preferences of 4 participants for one stimulus versus a number of qualitatively different stimuli, presented contingent on academic task completion. A paired-choice preference assessment was conducted followed by a reinforcer assessment using a combined reversal and multi-element design. The purpose of these procedures was to determine whether higher rates of responding would occur during conditions in which token reinforcement produced access to back-up reinforcers compared to a no reinforcement condition. Next, the opportunity to choose single versus varied token reinforcers was presented in a concurrent -chains arrangement. The dependent variables were the number of letters traced per min and the number of tokens earned per min during 3-min sessions, and the percentage of selections for single versus varied conditions. Results showed that response rates during the reinforcer assessment were higher during the reinforcement condition relative to the no reinforcement condition. A preference was not detected for 2 of 4 participants when the opportunity to choose from the same or qualitatively different reinforcers was presented. One of 4 participants preferred selecting the varied-choice condition (i.e., qualitatively different back-up reinforcers), and a second participant showed a similar pattern, but results were inconclusive due to limited data.

Four elementary school children were tested on 120 words containing the short e (e.g., ten, pen) and short a (e.g., tan, pan) sounds. Words were tested in the hear-write (H/W) and see-say (S/S) channels. No programmed consequences were scheduled during baseline (BL) tests 1-3. After BL, an error analysis categorized words based on channel error and topography of error. Praise was delivered during tests 4-6 for correct responses. Children's responses were variable within channel and across channels for a majority of words. By the end of the praise phase, there was a decrease in the number of words with errors, for all children in their error word group. Error topographies began to stabilize for some words during praise.

This study analyzed the effects of a training package containing response constraint, self-evaluation, reinforcement, and a fading procedure on written letter components and whole letter writing in four elementary school participants. The effect on accuracy of written components was evaluated using a multiple-baseline-across components and a continuous probe design of components, as well as pre-test, baseline, and post-test measures. The results of this study show that response constraint and self-evaluation quickly improved students' performance in writing components. Fading of the intervention was achieved quickly and performance maintained. Results also show that improvement in component writing improved whole letter and full name writing and letter reversals in the presence of a model were corrected.

Important advancements have been made in the identification of reinforcers over the past decade. The use of preference assessments has become a systematic way to identify preferred events that may function as reinforcers for an individual's behavior. Typically, preference assessments require participants to select stimuli through verbal surveys or engagement with stimuli as preferred or non-preferred. Not all studies go on to directly test the effects of the preferred stimuli, and even fewer studies directly test for the effects of the non- preferred stimuli. The present study systematically identified preferred and non-preferred stimuli in adult human subjects by verbal report and then proceeded to test the effects of both verbally reported preferred and non preferred events on single and concurrent schedules of reinforcement. The results are discussed in terms of contemporary concerns regarding preference and reinforcer assessments.

Pigeons were trained on a zero-delay identity match-to-sample task. Experiment 1 started with every correct match reinforced with grain access and subsequent conditions include higher fixed-ratio values. Experiment 2 included the same fixed-ratio values as experiment 1 with and without a limited hold (LH) on the opportunity to select a comparison stimulus. Prior research suggested that trials after reinforcement would have an increased likelihood of error, and that these errors would be reduced in LH conditions. Results confirmed this expected error pattern and in most LH conditions errors were reduced early in the ratio.

Few studies have systematically evaluated whether preferences can reliably be identified using brief procedures. Typically, studies have used brief procedures to select potential reinforcers for use in intervention procedures. A total of 17 food and leisure paired-choice preference assessments were administered to 10 subjects in order to evaluate the extent to which the results of a brief (i.e., single-session) assessment correspond with those from more extended procedures (i.e., 5 sessions). Eleven out of the 17 brief and extended assessments identified the same stimulus as the most preferred (highest rank). Outcomes suggest that a brief assessment can be useful when a single, potent reinforcing stimulus is desired, and an extended assessment should be conducted when a larger number of preferred stimuli is desired.

The present study contributes an apparatus and research paradigm useful in generating human performances sensitive to concurrent schedules of reinforcement. Five participants produced performances observed to be under temporal and ratio control of concurrent fixed interval-fixed ratio schedules. Two aspects of interaction between FI and FR schedules were distinguishable in the data. First, interaction between two schedules was observed in that changes in the value of one schedule affected behavior reinforced on another schedule. Second, switching from one pattern to the other functioned as an operant unit, showing stability during schedule maintenance conditions and sensitivity to extinction. These effects are discussed in the context of current views on behavior under concurrent schedules of reinforcement, and some implications for the conceptualization, measurement, analysis, and treatment of complex behavior are presented.

We examined the claim that equivalence classes contain all positive elements in a reinforcement contingency by asking whether negative stimuli in a reinforcement contingency will also form an equivalence class, based on their shared function as S-minus stimuli. In Experiment 1, 5 subjects were tested for equivalence for positive and negative stimuli. Testing of positive stimuli preceded testing of negative stimuli. Two of five subjects demonstrated equivalence for positive stimuli, and three subjects demonstrated equivalence for negative stimuli. In Experiment 2, order of testing was reversed. Four of six subjects demonstrated equivalence for positive stimuli, and none demonstrated equivalence for negative stimuli. In Experiment 3, positive and negative stimuli were tested together. Only one of five subject demonstrated equivalence for positive and negative stimuli. These data suggest that negative stimuli may enter an equivalence class, and so Sidman paradigm should be expanded. Order of testing was found as a meaningful variable.

The effects of two consequence delivery methods on task acquisition were evaluated within a multi-element design. A typical 3 year-old child and a 4 year-old child with autism participated in this study. The task for both children was to select a picture after the experimenter said its name. The consequence in one condition consisted of the experimenter handing the edible item to the children. The consequence in the other condition consisted of the children retrieving the edible item directly from the apparatus, located in a crevice underneath each picture. Results show slightly quicker acquisition in the condition where children retrieved the edible consequence. However, it is possible that other variables had greater influence on the task acquisition.

Negative reinforcement can be a powerful tool for behavior analysts, yet it is often overlooked as a treatment method. Pryor (1999) outlines a method for approaching a "timid" animal using a combination of negative reinforcement and positive reinforcement. When the animal stands still, the human operates a clicker, and then retreats from the animal. Gradually, the human moves closer to the animal through the clicking and retreating shaping process. Once the human is standing close enough, food may be offered as a positive reinforcer, and the negative reinforcer is canceled out. The purpose of this study was to experimentally demonstrate the click-retreat technique with cows. A multiple-baseline design across subjects was used to test this technique. Results show that the click and retreat technique was effective. Results are discussed in terms of the difference between the click-retreat technique and systematic desensitization.

Traditionally children with developmental disabilities who develop feeding issues can be at great risk for malnutrition. Failure to eat adequate amounts of food and/or insistence on eating a limited range of foods can be detrimental to a child's health and can lead to other behavioral difficulties. Feeding problems are difficult to treat because high levels of physical prompting can quickly create an aversion to eating as well as cause stress for both parents and children. Behavioral problems that range from moderate to extremely maladaptive can ensue. The question the present study addressed was whether or not a treatment package including only positive reinforcement and fading for a non-preferred food would result in independent eating of the targeted non-preferred food.

Previous research has shown that variability is a reinforceable dimension of operant behavior. Additionally, it has been demonstrated that learning is facilitated when variability in responding is high. In this research, variability was observed within an operant composed of any sequence of six left and right key presses. Variability was either a requirement for point delivery (VAR conditions) or points were delivered independent of variability (ANY conditions). Two groups of college undergraduates experienced different orders of conditions. One group began the experiment under VAR conditions, and the variability requirement was later removed. The other group began the experiment under ANY conditions, and the variability requirement was later added. A concurrently reinforced target sequence (i.e., an always-reinforced sequence of left and right key presses) was introduced to both groups after these orders of conditions had been experienced. A variety of outcomes resulted. Subjects learned the target sequence when variability was both high and low with non-target points concurrently available. Other subjects learned the target sequence after all non-target point deliveries had been suspended. One subject failed to acquire the target sequence at all. These results were compared to previous findings and possible explanations for the discrepancies were suggested.

The purpose of this experiment was to evaluate the effects of alternative contingencies on instruction following by an ABA design. Three college students consistently pressed keys 1-5-3 and 4-8-6 in the presence of the written instruction "Press 153" or "Press 486." During condition A, the contingencies for following and not following the instruction were the same: CON FR5 FR5 and CON FR20 FR20. During condition B, the contingencies for following and not following the instruction were different: CON FR20 FR5. For one participant, the schedule of reinforcement was then changed to FR30. The results showed that subjects followed instructions when the schedule of reinforcement was the same for instruction following and not following.

A functional analysis, conducted to assess the variables maintaining the chronic eye poking of a female diagnosed with profound mental retardation, indicated that the behavior persisted in the absence of social contingencies. A procedure was initiated in a training environment in which a punisher (mild reprimand) was delivered contingent on eye poking in the presence, but not in the absence, of a neutral stimulus (wristbands). Using a combination of multiple baseline and multielement experimental designs, it was determined that that eye poking was suppressed in the presence of the previously neutral stimulus, even in environments in which the reprimand contingency was inoperative.

The effects of non-differential reinforcement and differential reinforcement on problem behaviors and accuracy of responding of autistic children was examined. In experiment 1, one child with autism participated, and in experiment 2, two children with autism participated. In the non-differential reinforcement condition both prompted and unprompted responses were reinforced. In the differential reinforcement condition only unprompted responses were reinforced. Overall, problem behaviors were more frequent in the non-differential reinforcement condition. In experiment 1, accuracy was higher in the differential reinforcement condition, while experiment 2 showed inconclusive results with regards to accuracy. It is concluded that non-differential reinforcement can decrease problem behaviors in teaching situations, but may not be sufficient to ensure acquisition of target tasks.