UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
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Item Preventing Drowsy Driving in Young Adults Through Messaging Strategies that Influence Perceptions of Control and Risk(2024) Lee, Clark Johnson; Butler III, James; Beck, Kenneth H; Public and Community Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Drowsy driving is a serious health and safety problem in the United States: thousands of car crashes on U.S. roadways each year are attributed to this risky driving behavior. Although young drivers under the age of 26 years are especially at risk for being involved in drowsy driving car crashes, few anti-drowsy driving interventions targeting such drivers have been developed. Furthermore, most existing educational materials and interventions against drowsy driving have focused primarily on providing factual information about the dangers of drowsy driving and countermeasures against these dangers rather than on influencing beliefs and motivations underlying drowsy driving behavior, which may explain their apparent ineffectiveness at preventing drowsy driving behavior and resultant car crashes. Recent research indicates that messages targeting perceptions of control may be effective intervention strategies against drowsy driving behavior for young adult drivers by influencing their drowsy driving-related perceptions of risk, intentions, and willingness. This dissertation continues this line of research by pursuing two lines of inquiry. In Study #1, the efficacy of anti-drowsy driving messaging strategies designed to influence perceptions of control and risk related to drowsy driving behavior in reducing drowsy driving intentions, willingness, and behavior in a sample of young adult U.S. drivers between 18 and 25 years of age was evaluated through a randomized controlled trial. Study #1 sought to test the following hypotheses: Hypothesis 1: Participants exposed to interventional messaging strategies primarily aimed at lowering perceptions of control or heightening perceptions of risk related to drowsy driving report significantly less perceived control, greater perceived risk, less intentions, less willingness, and less behavior related to drowsy driving at 30-day post-intervention follow-up compared to participants exposed to messaging strategies providing only factual information about the dangers of drowsy driving; and Hypothesis 2: Participants exposed to interventional messaging strategies aimed at both lowering perceptions of control and heightening perceptions of risk related to drowsy driving report significantly less perceived control, greater perceived risk, less intentions, less willingness, and less behavior related to drowsy driving at 30-day post-intervention follow-up compared to participants exposed to messaging strategies providing only factual information about the dangers of drowsy driving, messaging strategies primarily aimed at lowering perceptions of control related to drowsy driving, or messaging strategies primarily aimed at heightening perceptions of risk related to drowsy driving. In Study #2, the relationships between perceived behavioral control, risk perception, intentions, willingness, and drowsy driving behavior in a sample of young adult U.S. drivers between 18 and 25 years of age were examined. Study #2 sought to test the following hypotheses: Hypothesis 3: The impact of interventional messaging strategies targeting drowsy driving perception of control on drowsy driving intentions, willingness, and behavior is mediated by drowsy driving risk perception such that messages lowering drowsy driving perceptions of control also heighten drowsy driving risk perception, which in turn decreases drowsy driving intentions, willingness, and behavior; Hypothesis 4: Interventional messaging strategies targeting drowsy driving-related perceptions of control or risk have a greater impact on drowsy driving willingness than on drowsy driving intentions; and Hypothesis 5: Drowsy driving willingness is a stronger predictor of drowsy driving behavior than is drowsy driving intentions. Study #1 provided supporting evidence of short-term cognitive effects but not short-term behavioral effects after exposure to messaging interventions designed to influence perceptions of control and risk related to drowsy driving behavior. Perceptions of risk were especially influenced by the messaging strategies examined, including those that provided only factual, knowledge-based information about drowsy driving. Study #2 provided supporting evidence that perceived behavioral control influenced drowsy driving intentions and drowsy driving willingness indirectly through perceptions of risk. Furthermore, willingness to drive drowsy was a stronger predictor of actual drowsy driving behavior than intentions to drive drowsy. The findings from these two studies should inform future research aimed at developing more effective messaging strategies against drowsy driving behavior in young adults.Item School Climate and Teacher Use of Strategies Linked to Bullying Perpetration and Victimization(2022) Gliese, Sara; Wang, Cixin; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bullying in school settings is a major concern with approximately 22% of children in the U.S. experiencing some form of bullying (National Crime Victimization Survey, 2019). However, there is little to no current research specific to how teachers may play a modeling role through the behavior management strategies they use in the classroom to impact the likelihood and rate of bullying perpetration and victimization occurring among diverse middle school students. Additionally, while school climate has been linked to bullying perpetration and victimization, almost no research has examined how teacher strategies may impact school climate, which in turn predict bullying. This study sought to examine whether student perceptions of teacher use of positive (i.e., praise and reward) and punitive (i.e., yelling and punishment) strategies and school climate are linked to the likelihood and rates of bullying perpetration and victimization. In addition, it also examined whether school climate may have mediated the relationship between student perceptions of teacher strategies and bullying perpetration and victimization and whether gender and grade moderated these relations. Data were collected from 545 middle school students (Age: M = 13.12, SD = 0.76) from a diverse middle school in Southern California, using a multi-measure online survey administered at school. Students/families could opt-out of the survey. Data were analyzed following a two-part model suited for semi-continuous variables containing large numbers of zeros, with the first step being binary logistic regression with the whole sample, and the second step being linear regressions for cases with non-zero values using a victim-only sample and a perpetrator-only sample. Results of this study indicated that perceptions of punitive teacher strategies were linked to the likelihood of victimization, as well as the rates of perpetration and victimization for those who endorsed involvement. Perceptions of positive strategies were associated with the likelihood of victimization for those in their first year of middle school, but not for older students. Additionally, school climate was linked to the likelihood of both perpetration and victimization, but not rates. Lastly, school climate created a significant indirect effect when added to the models for positive and punitive strategies predicting the likelihoods victimization and perpetration, and positive strategies predicting the rates, and should be investigated longitudinally as a possible mediator. Overall, results supported the hypotheses that the strategies teachers use to manage behavior in the classroom and school climate may be linked to students’ involvement in bullying. Implications for practitioners and future work were presented.Item CORTICAL AND STRIATAL MECHANISMS OF VALUE-BASED DECISION-MAKING AND THEIR DISRUPTION IN ADDICTION(2022) Hadfield, Heather; Roesch, Matthew R; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)For decisions both great and small, the brain utilizes an extensive network that integrates value assessment, reward prediction, and motivation to quickly and efficiently select the most beneficial option while minimizing aversive consequences for ourselves. Numerous psychiatric conditions, in particular drug addiction, can disrupt this network and impair decision-making behavior. It is therefore important to understand the neural underpinnings of decision-making and how neural activity and its associated behavior are disrupted by drugs of abuse. My dissertation will expand on current studies of this circuitry by examining epigenetic and neurophysiological mechanisms of value-based decision-making within two regions of the brain. In my final aim, I explore a new behavioral assay that may be used to study these and other regions relevant for value-based decision-making in the context of another complex behavior.In my first aim, I have recorded from single neurons in the rat dorsal lateral striatum (DLS) after overexpressing histone deacetylase 5 (HDAC5), an epigenetic enzyme implicated in incubation of craving, in the dorsal striatum (DS). In my second aim I used pharmacological lesion and single-neuron recording combined with cocaine self-administration techniques to study anterior insula, a region well-known for combining internal and external experience but largely under-studied in the context of higher cognitive processes. These studies were conducted while rats performed an odor-guided decision-making task in which the value of rewards were manipulated by either the delay to or the size of the reward across a series of trial blocks. I have found overexpression of HDAC5 in DS promoted inflexible, faster, and automatic behavior in the decision-making task while increasing DLS’s response to reward cues- similar to previous studies examining DLS activity and behavior after cocaine self-administration. In my studies of insula, I found recording from this region novel, global signals of reward value that seemed to reflect the overall structure of the behavioral task. Following cocaine-exposure, these signals were diminished while immediate rewards were over-represented on a trial-by-trial basis, leading to steeper discounting of delayed rewards. Additional studies lesioning this region promoted faster reaction times and increased goal-directed behavior. Together, these results provide insights into how drugs of abuse may impair behavioral flexibility and the tracking of long-term changes in reward from multiple mechanisms. However, it is still unknown how these changes in value assessment give rise to complex impairments of behavior. As a first step to addressing this issue, I used a new task to examine how chronic drug use- which disrupts both neural signals in the corticostriatal circuit and epigenetic enzymes- also impairs the complex ability to delay gratification. This final study replicated well-established findings of drug-induced reversal-learning impairment, but surprisingly did not alter decision-making. This collection of work demonstrates the complexity with which drug exposure alters neural circuitry and value-based decision-making, and additionally shows the importance of utilizing complex behavioral assays to explore the relationship between brain and behavior.Item THE ROLE OF THE VENTRAL STRIATUM AND AMYGDALA IN REINFORCEMENT LEARNING(2021) Taswell, Craig Anthony; Butts , Daniel; Averbeck , Bruno; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Adaptive behavior requires that organisms choose wisely to gain rewards and avoid punishment. Reinforcement learning refers to the behavioral process of learning about the value of choices, based on previous choice outcomes. From an algorithmic point of view, rewards and punishments exist on opposite sides of a single value axis. However, simple distinctions between rewards and punishments and their theoretical expression on a single value axis hide considerable psychological complexities that underlie appetitive and aversive reinforcement learning. A broad set of neural circuits, including the amygdala and frontal-striatal systems, have been implicated in mediating learning from gains and losses. The ventral striatum (VS) and amygdala have been implicated in several aspects of this process. To examine the role of the VS and amygdala in learning from gains and losses, we compared the performance of macaque monkeys with VS lesions, with amygdala lesions, and un-operated controls on a series of reinforcement learning tasks. In these tasks monkeys gained or lost tokens, which were periodically cashed out for juice, as outcomes for choices. We found that monkeys with VS lesions had a deficit in learning to choose between cues that differed in reward magnitude. Monkeys with VS lesions performed as well as controls when choices involved a potential loss. In contrast, we found that monkeys with amygdala lesions performed as well as controls across all conditions. Further analysis revealed that the deficits we found in monkeys with VS lesions resulted from a reduction in motivation, rather than the monkeys’ inability to learn the stimulus-outcome contingency.Item HOW AND WHEN SIGNALING IMPACTS CONSUMPTION(2021) Kim, Nicole You Jeung; Ratner, Rebecca K.; Wang, Yajin; Business and Management: Marketing; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation includes three essays that investigate the impact of signals that certain consumption choices can send to other consumers. In particular, each essay focuses on how consumers’ consumption-related decisions (e.g., choice of hedonic items, selecting low variety, and communicating that one has no preference) impact an observing audience’s perceptions of the consumer and the subsequent impacts on the observer. The first essay demonstrates that consumers strive to position themselves as attractive friends by making hedonic consumption decisions. While consumers shift to hedonic consumption, anchoring on their belief that others would heavily value fun when it comes to friendship, this essay demonstrates that consumers themselves actually value other aspects of friendship more, such as meaningfulness. As a result of this discrepancy in the belief of friendship, hedonic choice does not effectively help consumers cultivate friendship with another person. The second essay investigates the signals that selecting a low (vs. high) variety of items sends to observers. Choosing low variety signals to observers that the consumer has accumulated consumption experiences in the past, and thus has greater expertise, compared to choosing high variety. This signal of expertise endows the consumer with influence to impact observers to make consumption choices that mimic the consumer and be more willing to take the consumer’s recommendations. The third essay examines the impact of expressing no preference in a joint decision making context. While consumers expect to make the decision easier for the recipient, recipients of no preference communication (vs. explicit preference communication), experience greater decision difficulty. This unexpected negative impact occurs because recipients of no preference communication perceive that the communicator actually has preferences that they are hiding. Further, because recipients infer that these hidden preferences are dissimilar to one’s own preferences, they end up making a choice for the joint consumption that they personally less prefer.Item Understanding and Retraining the Causal Attributions for Exercise Intenders(2019) Singpurwalla, Darius; Iso-Ahola, Seppo E; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Given that ~50% of all exercise intenders will fall into the intention-behavior gap (i.e., a situation where people fail to act on their intentions), it is necessary to identify the constructs and/or theories that can explain the discord between intention and behavior (i.e., the intention-behavior gap). For this purpose, the present research was conducted through two studies that were designed to test the efficacy of causal attributions as a means to reduce the intention-behavior discord. The first study collected information from 952 individuals on their exercise behavior and their associated causal attributions over a six-week period. The findings from this study included: (1) those individuals who fell into the intention-behavior gap made self-serving attributions for their exercise failure; (2) Weiner’s model accurately predicted several of the affective and cognitive responses to exercise behavior for the sample of exercise intenders; and (3) causal attributions were not found to be effective moderators of the intention-behavior relationship. The second study was an experiment that tested whether an attribution retraining intervention could improve exercise behavior for a sample of sedentary, exercise intenders (n=200). Results of this study were mixed as the intervention appeared to have been able to modify one of the targeted attributional dimensions (control), but the effect was not strong enough to change the exercise behavior of the participants in the experimental group. It is suggested that attributions may not be able to reduce the gap because they represent conscious deliberations of the behavior, while sustained exercise is based on nonconscious processing of relevant information to make exercise an automatic behavior.Item A study of the developmental sequence of the play behavior of children as revealed in the anecdotal records of teachers(1952) Renfroe, Olive; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Item Studies on chronic inanition and recovery in young male albino rats(1947) Quimby, Freeman H.; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Item Verbal behavior and attitudes(1950) Havron, M. Dean; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Item A genetic study of brand loyalty(1941) Guest, Lester Philip; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)