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 Information Uncertainty Influences Learning Strategy from Sequentially Delayed Rewards(2023) Maulhardt, Sean Richard; Charpentier, Caroline; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The problem of temporal credit assignment has long been posed as a nontrivial obstacle to identifying signal from data. However, human solutions in complex environments, involving repeated and intervening decisions, as well as uncertainty in reward timing, remain elusive. To this end, our task manipulated uncertainty via the amount of information given in their feedback stage. Using computational modeling, two learning strategies were developed that differentiated participants’ updates of sequentially delayed rewards: eligibility trace whereby previously selected actions are updated as a function of the temporal sequence - and tabular update - whereby additional feedback information is used to only update systematically-related rather than randomly related past actions. In both models, values were discounted over time with an exponential decay. We hypothesized that higher uncertainty would be associated with (i) a switch from tabular to eligibility strategy and (ii) higher rates of discounting. Participants’ data (N = 142) confirmed our first hypothesis, additionally revealing an effect of the starting condition. However, our discounting hypothesis had only weak evidence of an effect and remains an open question for future studies. We explore potential explanations for these effects and possibilities of future directions, models, and designs.Item UNDERSTANDING LEARNING AND SKETCHING EXPERIENCES OF CHILDREN INVOLVED IN STEM DESIGN(2023) Shokeen, Ekta; Williams-Pierce, Caro Dr.; Library & Information Services; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Sketching is considered a helpful activity in STEM design and education. Scholars have argued for including children in designing technology as it has been found to improve product design and leads to social and cognitive benefits for children. However, little is known about children’s learning and sketching experiences when participating in design activities. How do children sketch during design activities? How do children learn about sketching in design activities? What information do they share via their sketches? What information do they use for sketching? How do they use sketching in the overall design process? How do learning and sketching relate to STEM design? This three-paper dissertation uses empirical and theoretical approaches to address these questions. The first paper uses an ethnographic case study approach to qualitatively examine information-sharing practices and learning opportunities from children’s engagement in interest-driven sketching. Findings suggest that sketching can provide multiple learning opportunities to children. Also, it can be helpful to gather information about the broader contexts of children’s lives which can help identify their needs and improve the future design of technologies for children. The second paper presents a theoretical framework, Radical Constructivist Cooperative Inquiry (RCCI), for understanding children’s learning in design activities. Based on the theoretical synthesis of the cooperative inquiry design approach and the radical constructivist perspective of learning, RCCI establishes six pillars of learning in design. Finally, the paper discusses how these six pillars can be utilized in design activities to support children’s learning. The third paper is a secondary analysis of video data of children’s learning and sketching experiences in engineering design in their home environments. It focuses on examining the relationship between children’s sketching and learning following the RCCI framework with the thematic analysis method. Results suggest that sketching can engage children in learning about STEM skill sets. These three papers collectively contribute empirically and theoretically to building knowledge about improving and sustaining design cycles by children in STEM learning contexts.Item Island Constraints: What is there for children to learn?(2022) Hirzel, Mina; Lidz, Jeffrey; Lau, Ellen; Linguistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation presents behavioral studies that target the early syntactic representations of wh-movement during infancy and early childhood. Previous studies show that by 20 months-old, infants represent wh-movement and use this knowledge to respond to wh-questions during language comprehension tasks (Gagliardi 2012; Gagliardi et al., 2016; Seidl et al., 2003). Studies probing the nature of early representations of wh-movement show that by around 4 years-old, children represent island constraints (e.g., de Villiers et al., 1990; de Villiers & Roeper, 1995a, 1995b; Fetters & Lidz, 2016; Goodluck et al., 1992). It remains unclear how knowledge of wh-movement develops. What is the source of this ‘empirical gap’ between the onset of knowledge of wh- movement, and the observation that children respect island constraints? One possibility is that knowledge of island constraints is a component of Universal Grammar (e.g., Chomsky 1965, 1986; Hornstein & Lightfoot 1981). In this case, the ‘empirical gap’ in the linguistic abilities of infants compared to young children isn’t indicative of their linguistic knowledge, but rather the difficulties with testing infants and toddlers on complex syntax. Another possibility is that knowledge of island constraints is acquired via experience (e.g., Pearl & Sprouse, 2013). In this case, the ‘empirical gap’ reflects a knowledge gap, and there’s no evidence for knowledge of island constraints during infancy because it has yet to be acquired. Experiment 1 shows that by 19 months-old, infants have knowledge of wh-movement, and use this knowledge during language comprehension. Results are consistent with recent work which shows that 18 month-olds, but not 17 month-olds, know that wh-phrases co-occur with gap positions in wh-object questions (Perkins & Lidz, 2021). Experiment 2 shows that 3 year-olds respect locality constraints on wh-movement in wh- questions, and Experiment 3 shows that adults behave as expected on this task. Experiments 4 and 5 test children and adults on locality constraints on wh- movement in relative clauses, but these results are inconclusive (likely due to difficulties with moving the task online). The results of Experiment 3 raises challenges for learning hypotheses of island constraints which emphasize the role of linguistic experience. Learning models which propose that linguistic experience is the key factor in the acquisition of island constraints must consider these behavioral results when estimating the amount of data that the learner needs to solve the acquisition problem. These behavioral results are consistent with the hypothesis that knowledge of island constraints is innate, but further work is needed to close the ‘empirical gap’ between the onset of knowledge of wh- movement and the onset of knowledge of island constraints.Item Lifted Up or Feet on the Ground? How Leader Emotional Balancing Moderates the Effect of Developmental Feedback on Employee Learning(2022) Guo, Siyan; Seo, Myeong-Gu; Business and Management: Management & Organization; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Leaders expect their developmental feedback to help employees develop skills and improve performance, yet the effect of developmental feedback on learning remains unclear. In this dissertation, the concept of developmental feedback (DFB) is extended to include two dimensions, gap identification and gap elimination. I focus on the affective mechanisms underlying the DFB – learning relationship and identify trade-offs in each of the DFB dimensions. I argue that while gap elimination elicits employee positive affect (PA) that facilitates learning via increased learning self-efficacy, it undermines learning via PA and decreased learning need recognition. In addition, gap identification induces employee negative affect (NA) that works in the opposite way. Emotional balancing, or leaders’ dynamic engagement in both affect improving and affect worsening behaviors, is proposed to attenuate the negative mechanisms. I conducted a pilot study in the field to develop measures for the two DFB dimensions, followed by a three-wave, multisource field study to test my theoretical model at the between-person level, and a daily dairy field study to test the model at the within-person level. The findings largely support my proposed model. The results indicate that gap identification positively predicts employee NA, while gap elimination predicts PA. Gap identification is positively associated with learning via employee learning need recognition, but negatively predicts learning via employee NA and learning self-efficacy. I also find that gap elimination positively predicts learning through PA and improved employee self-efficacy in learning. Importantly, the results demonstrate the beneficial effects of emotional balancing, which significantly moderates the effects of PA and NA. Taken together, these findings indicate that receiving DFB is a highly emotional experience that creates a tension between feeling uplifted and keeping feet on the ground, and leaders can use emotional balancing to manage employee affect to achieve better learning outcomes.Item Essays on Digital Content Provision and Consumption(2022) Wang, Chutian; Zhou, Bobby; Joshi, Yogesh V; Business and Management: Marketing; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Consumption of digital content has become an inseparable part of consumers' lives today. As providers of digital content, media platforms continuously seek to pursue pricing and product design strategies that increase their profits. This dissertation studies media platforms' digital content provision and consumers' consumption decisions. In the first essay, we focus on the pricing of digital content and analyze the impact of consumers' endogenous content consumption on platforms' paywall strategies. Paywalls increase subscription revenues for platforms, but they also impact content consumption and thus advertising revenues. We build an analytical model that endogenizes consumers' content consumption decisions. We find that under moderate ad rates, a metered paywall under which a limited amount of content is provided for free is optimal when consumers display sufficient heterogeneity in their costs of consuming content. We also study how the amount of free content and the subscription price vary with changes in the advertising rate and consumer preference. In the second essay, we analyze the accuracy of news reported by the news media. When consumers are seeking the truth and accurate reporting is costly, determining the optimal level of accuracy in reporting is a strategic decision for a profit-maximizing media firm. We build an analytical model to study this media firm decision. When consumers and the media firm are both initially uncertain about the true state of the world, we show that the media firm always chooses full accuracy if investigation and reporting are of low cost. However, if achieving accuracy is sufficiently costly, the media firm provides news only when consumers' priors regarding the truth are not too extreme, so that they see enough value in news consumption. Interestingly, consumers' truth-seeking and the firm's profit maximization can lead to reporting inaccuracy and exaggeration of the more likely state a priori. We also discuss the implications of polarization in consumers’ prior beliefs and the media firm’s different objectives on the accuracy of news.Item Equilibrium Models with Dynamic Demand and Dynamic Supply(2019) Hui, Shen; Sweeting, Andrew T; Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation comprises two studies of equilibrium models with both dynamic demand and dynamic supply sides. The first is an empirical study of the US video games industry, and the second is a theoretical study. Chapters 1 and 2 develop a model for quantifying the role of social learning in consumers’ dynamic demand and finding optimal intertemporal prices for profit maximizing firms in a market populated by forward-looking social learners. Optimal prices are a result of a Markov perfect equilibrium played between the firm and the consumers. Nested in the market equilibrium is a demand equilibrium played among consumers who make the “right” purchase/wait decisions given endogenously produced product information. The empirical exercises are conducted in two steps. The first step estimates demand parameters, including those associated with social learning. Endogeneity of prices is remedied with a pseudo pricing policy function of relevant state variables. In the second step, optimal prices are found by the Mathematical Programming with Equilibrium Constraints (MPEC) approach. The model is applied to the US video games industry with sales data of PlayStation 3 games. The results reveal that (1) compared to static social learning, forward- looking social learning reduces equilibrium profits of games in the sample by $5.2M (28.4%) on average; (2) an incorrect belief of consumers’ forward-looking behavior reduces a firm’s profits by a maximum of 29.92%. These results indicate great value for researches on consumers’ forward-looking social learning behavior. In chapter 3 we study the effect of adding strategic buyers to the computational model of dynamic price competition when sellers experience learning-by-doing and organizational forgetting developed by Besanko et al. (2010) (BDKS). The addition is motivated by the presence of repeat buyers in many industries where learning- by-doing has been documented, and the role that the assumption of a monopsony strategic buyer has played in the theoretical literature. We characterize the degree of strategic buyer behavior using a single parameter, and show that even quite limited strategic behavior changes the equilibrium correspondance by almost entirely eliminating the multiplicity of equilibria emphasized by BDKS, and ensuring that no seller is likely to dominate the industry in the long-run. We examine how the welfare of both buyers and sellers varies with the degree of strategic buyer behavior.Item The benefits of testing: Individual differences based on student factors(2017) Robey, Alison Marie; Dougherty, Michael R; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The testing effect, the notion that retrieval practice compared to restudying information leads to greater and longer retention, is one of the most robust findings in cognitive science. However, not all learners experience a benefit from retrieval practice. Many manipulations that influence the benefits of the testing effect have been explored, however, there is still much to learn about potential individual differences in the benefits of retrieval practice over restudy. As the testing effect grows in popularity and increasing numbers of classrooms begin implementing retrieval practice, it is essential to understanding how students’ individual differences and cognitive abilities contribute to the effect. For my dissertation, I explore how students’ cognitive abilities, specifically, episodic memory, general fluid intelligence, and strategy use, relate to the benefit of retrieval practice. In Study 1, I developed a new measure to simultaneously capture two aspects of strategy use: variation in what strategies learners use and variation in how learners use strategies. In Study 2, I examine how these two types of strategy use, along with episodic memory and general fluid intelligence can be used to predict the magnitude of the testing effect. Converging evidence from multiple analyses suggests variation in how learners use strategies was the only individual difference to influence the benefit learners receive from retrieval practice. More specifically, learners who are less adaptive and flexible in their strategy use show a greater benefit than more skilled strategy users. These findings have implications both for improving existing theories of the mechanisms of the testing effect and for determining how to best incorporate retrieval practice into classroom settings.Item Playing for Real: Designing Alternate Reality Games in Learning Contexts(2016) Bonsignore, Elizabeth Marie; Druin, Allison; Library & Information Services; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Alternate Reality Game (ARG) represent a new genre of transmedia practice where players hunt for scattered clues, make sense of disparate information, and solve puzzles to advance an ever-evolving storyline. Players participate in ARGs using multiple communications technologies, ranging from print materials to mobile devices. However, many interaction design challenges must be addressed to weave these everyday communication tools together into an immersive, participatory experience. Transmedia design is not an everyday process. Designers must create and connect story bits across multiple media (video, audio, text) and multiple platforms (phones, computers, physical spaces). Furthermore, they must engage with players of varying skill levels. Few studies to-date have explored the design process of ARGs in learning contexts. Fewer still have focused on challenges involved in designing for youth (13-17 years old). In this study, I explore the process of designing ARGs as vehicles for promoting information literacy and participatory culture for adolescents (13-17 years old). Two ARG design scenarios, distinguished by target learning environment (formal and informal context) and target audience (adolescents), comprise the two cases that I examine. Through my analysis of these two design cases, I articulate several unique challenges faced by designers who create interactive, transmedia stories for – and with – youth. Drawing from these design challenges, I derive a repertoire of design strategies that future designers and researchers may use to create and implement ARGs for teens in learning contexts. In particular, I propose a narrative design framework that allows for the categorization of ARGs as storytelling constructs that lie along a continuum of participation and interaction. The framework can serve as an analytic tool for researchers and a guide for designers. In addition, I establish a framework of social roles that designers may employ to craft transmedia narratives before live launch and to promote and scaffold player participation after play begins. Overall, the contributions of my study include theoretical insights that may advance our understanding of narrative design and analysis as well as more practical design implications for designers and practitioners seeking to incorporate transmedia features into learning experiences that target youth.Item ADVENTURES ON NETWORKS: DEGREES AND GAMES(2015) Pal, Siddharth; Makowski, Armand; La, Richard; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A network consists of a set of nodes and edges with the edges representing pairwise connections between nodes. Examples of real-world networks include the Internet, the World Wide Web, social networks and transportation networks often modeled as random graphs. In the first half of this thesis, we explore the degree distributions of such random graphs. In homogeneous networks or graphs, the behavior of the (generic) degree of a single node is often thought to reflect the degree distribution of the graph defined as the usual fractions of nodes with given degree. To study this preconceived notion, we introduce a general framework to discuss the conditions under which these two degree distributions coincide asymptotically in large random networks. Although Erdos-Renyi graphs along with other well known random graph models satisfy the aforementioned conditions, we show that there might be homogeneous random graphs for which such a conclusion may fail to hold. A counterexample to this common notion is found in the class of random threshold graphs. An implication of this finding is that random threshold graphs cannot be used as a substitute to the Barabasi-Albert model for scale-free network modeling, as proposed in some works. Since the Barabasi-Albert model was proposed, other network growth models were introduced that were shown to generate scale-free networks. We study one such basic network growth model, called the fitness model, which captures the inherent attributes of individual nodes through fitness values (drawn from a fitness distribution) that influence network growth. We characterize the tail of the network-wide degree distribution through the fitness distribution and demonstrate that the fitness model is indeed richer than the Barabasi-Albert model, in that it is capable of producing power-law degree distributions with varying parameters along with other non-Poisson degree distributions. In the second half of the thesis, we look at the interactions between nodes in a game-theoretic setting. As an example, these nodes could represent interacting agents making decisions over time while the edges represent the dependence of their payoffs on the decisions taken by other nodes. We study learning rules that could be adopted by the agents so that the entire system of agents reaches a desired operating point in various scenarios motivated by practical concerns facing engineering systems. For our analysis, we abstract out the network and represent the problem in the strategic-form repeated game setting. We consider two classes of learning rules -- a class of better-reply rules and a new class of rules, which we call, the class of monitoring rules. Motivated by practical concerns, we first consider a scenario in which agents revise their actions asynchronously based on delayed payoff information. We prove that, under the better-reply rules (when certain mild assumptions hold), the action profiles played by the agents converge almost surely to a pure-strategy Nash equilibrium (PSNE) with finite expected convergence time in a large class of games called generalized weakly acyclic games (GWAGs). A similar result is shown to hold for the monitoring rules in GWAGs and also in games satisfying a payoff interdependency structure. Secondly, we investigate a scenario in which the payoff information is unreliable, causing agents to make erroneous decisions occasionally. When the agents follow the better-reply rules and the payoff information becomes more accurate over time, we demonstrate the agents will play a PSNE with probability tending to one in GWAGs. Under a similar setting, when the agents follow the monitoring rule, we show that the action profile weakly converges to certain characterizable PSNE(s). Finally, we study a scenario where an agent might erroneously execute an intended action from time to time. Under such a setting, we show that the monitoring rules ensure that the system reaches PSNE(s) which are resilient to deviations by potentially multiple agents.Item Social Emotional Memory and Negative Symptoms in Individuals with Schizophrenia(2015) Bradshaw, Kristen Renee; Blanchard, Jack J; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The current study investigated social and nonsocial emotional memory in schizophrenia, the relation of impairments in the recall of positive stimuli to increased negative symptoms, and the mediating role of defeatist performance beliefs. Twenty-three individuals with schizophrenia and twenty-four healthy controls completed clinical symptom interviews, social and nonsocial laboratory emotional memory tasks, and a measure of dysfunctional attitudes. Results indicated that on a social affective learning task, in comparison to controls, the schizophrenia participants were impaired in their ability to exhibit minimal affective learning of positive pairings. Defeatist performance beliefs did not mediate the relation between recall of positive stimuli and experiential negative symptoms. These findings suggest that it is primarily in the social domain that we see deficits in emotional memory in schizophrenia, and that this impairment in the ability to learn positive social associations may be linked to decreased motivation to engage in social, vocational, and recreational activities.