Theses and Dissertations from UMD
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Item HOW BILINGUALS' COMPREHENSION OF CODE-SWITCHES INFLUENCES ATTENTION AND MEMORY(2024) Salig, Lauren; Novick, Jared; Slevc, L. Robert; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bilinguals sometimes code-switch between their shared languages. While psycholinguistics research has focused on the challenges of comprehending code-switches compared to single-language utterances, bilinguals seem unhindered by code-switching in communication, suggesting benefits that offset the costs. I hypothesize that bilinguals orient their attention to speech content after hearing a code-switch because they draw a pragmatic inference about its meaning. This hypothesis is based on the pragmatic meaningfulness of code-switches, which speakers may use to emphasize information, signal their identity, or ease production difficulties, inter alia. By considering how code-switches may benefit listeners, this research attempts to better align our psycholinguistic understanding of code-switch processing with actual bilingual language use, while also inspiring future work to investigate how diverse language contexts may facilitate learning in educational settings. In this dissertation, I share the results of three pre-registered experiments with Spanish-English bilinguals that evaluate how hearing a code-switch affects attention and memory. Experiment 1a shows that code-switches increase bilinguals’ self-reported attention to speech content and improve memory for that information, compared to single-language equivalents. Experiment 1b demonstrates that this effect requires bilingual experience, as English-speaking monolinguals did not demonstrate increased attention upon hearing a code-switch. Experiment 2 attempts to replicate these results and establish the time course of the attentional effect using an EEG measure previously associated with attentional engagement (alpha power). However, I conclude that alpha power was not a valid measure of attention to speech content in this experiment. In Experiment 3, bilinguals again showed better memory for information heard in a code-switched context, with a larger benefit for those with more code-switching experience and when listeners believed the code-switches were natural (as opposed to inserted randomly, removing the element of speaker choice). This suggests that the memory benefit comes from drawing a pragmatic inference, which likely requires prior code-switching experience and a belief in code-switches’ communicative purpose. These experiments establish that bilingual listeners derive attentional and memory benefits from ecologically valid code-switches—challenging a simplistic interpretation of the traditional finding of “costs.” Further, these findings motivate future applied work assessing if/how code-switches might benefit learning in educational contexts.Item Essays on the Cognitive Foundations of Economics(2024) Yegane, Ece; Masatlioglu, Yusufcan; Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In Chapter 1, I model a decision maker who observes available alternatives according to a list and stochastically forgets some alternatives. Each time the decision maker observes an item in the list, she recalls previous alternatives with some probability, conditional on those alternatives being recalled until this point. The decision maker maximizes a preference relation over the set of alternatives she can recall. I show that if every available alternative is chosen with strictly positive probability, the preference order and the list order must coincide in any limited memory representation. Under the full support assumption, the preference ordering, the list ordering and the memory parameters are uniquely identified up to the ranking of the two least preferred alternatives. I provide conditions on observable choice probabilities that characterize the model under the full support assumption. I then apply our model to study the pricing problem of a monopolist who faces consumers with limited memory. I show that when the probability of forgetting is high, the monopolist is better off charging a lower price than the optimal price in the perfect memory case. In Chapter 2, Yusufcan Masatlioglu and I study how the allocation of attention to different options and the accessibility of options from memory affect decision making. To distinguish between attention and memory, we propose a two-stage stochastic consideration set formation process. An alternative enters the decision maker’s consideration set if it is investigated in the initial attention stage and is remembered in the subsequent recall stage. In the initial attention stage, the decision maker investigates each available alternative with some alternative-specific probability. In the recall stage, the decision maker recalls each alternative that she investigated in the attention stage with some probability. The probability of recalling an alternative depends on the memorability of the alternative and its position in the order of investigation in the attention stage. Investigating an alternative more recently enhances the probability of recalling it. The decision maker chooses the option that maximizes her preference relation over her consideration set. Under the assumption that the investigation of alternatives is observable, we provide testable implications on choice behavior and show that the revealed preference, attention parameters and memory parameters can be uniquely identified from observable repeated choices.Item Towards a Theory of Transmedial Immersion(2020) Frew, Kathryn Kaczmarek; Kraus, Kari; English Language and Literature; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Immersion names a physical, mental, and emotional state in which narrative can take control over a reader. Traditional theories of immersion, rooted in the metaphors of enchantment and transportation, assume that the boundaries of the text constitute the boundaries of the reader’s engagement with the story. In other words, if you close the book, immersion ends. Transmedia narratives, such as the Matrix franchise, challenge these assumptions because the story moves across media boundaries. By putting theories from disciplines such as psychology, cognitive science, narratology, and media studies in conversation and testing them against case studies of transmedia narratives, I propose a new theory of transmedial immersion that accommodates all narratives, particularly those crossing media boundaries. Transmedial immersion is the phenomenological experience of a narrative by which the features of the storyworld, characters, and plot become the primary focus of the reader/viewer/player’s consciousness. This immersion bleeds beyond the boundaries of the medium and narrative experience, allowing it to be individual or communal. As I show through a reading of the interaction of print text, augmented reality, and digital narrative in The Ice-Bound Concordance, transmedial immersion relies on distributed, rather than focused, attention, and embraces the materiality and hypermediacy of the reading/viewing/playing experience. Contrary to assumed effortlessness, transmedial immersion requires cognitive effort as readers collate and assemble all the aspects of the narrative. For example, players of the alternate reality games DUST and The Tessera use cognitive blending (as described by Mark Turner) to blur the ontological boundaries of fiction and reality, demonstrated in their use of metalepsis. Finally, transmedial immersion allows the narrative to be simultaneously enjoyed and critiqued, an approach Alexis Lothian calls “critical fandom.” The theory explains how Harry Potter fans reacted to the Fantastic Beasts movies by embracing Newt Scamander as an unlikely hero while raising concerns about cultural appropriation and queer representation. This theory of transmedial immersion not only provides a framework for understanding narrative engagement in the new media landscape, it also prompts literary scholars to reexamine how their assumptions about the process of reading, viewing, and playing texts in a single medium inform their criticism.Item CORTICAL REPRESENTATION OF SPEECH IN COMPLEX AUDITORY ENVIRONMENTS AND APPLICATIONS(2017) Puvvada, Venkata Naga Krishna Chaitanya; Simon, Jonathan Z; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Being able to attend and recognize speech or a particular sound in complex listening environments is a feat performed by humans effortlessly. The underlying neural mechanisms, however, remain unclear and cannot yet be emulated by artificial systems. Understanding the internal (cortical) representation of external acoustic world is a key step in deciphering the mechanisms of human auditory processing. Further, understanding neural representation of sound finds numerous applications in clinical research for psychiatric disorders with auditory processing deficits such as schizophrenia. In the first part of this dissertation, cortical activity from normal hearing human subjects is recorded, non-invasively, using magnetoencephalography in two different real-life listening scenarios. First, when natural speech is distorted by reverberation as well as stationary additive noise. Second, when the attended speech is degraded by the presence of multiple additional talkers in the background, simulating a cocktail party. Using natural speech affected by reverberation and noise, it was demonstrated that the auditory cortex maintains both distorted as well as distortion-free representations of speech. Additionally, we show that, while the neural representation of speech remained robust to additive noise in absence of reverberation, noise had detrimental effect in presence of reverberation, suggesting differential mechanisms of speech processing for additive and reverberation distortions. In the cocktail party paradigm, we demonstrated that primary like areas represent the external auditory world in terms of acoustics, whereas higher-order areas maintained an object based representation. Further, it was demonstrated that background speech streams were represented as an unsegregated auditory object. The results suggest that object based representation of auditory scene emerge in higher-order auditory cortices. In the second part of this dissertation, using electroencephalographic recordings from normal human subjects and patients suffering from schizophrenia, it was demonstrated, for the first time, that delta band steady state responses are more affected in schizophrenia patients compared with healthy individuals, contrary to the prevailing dominance of gamma band studies in literature. Further, the results from this study suggest that the inadequate ability to sustain neural responses in this low frequency range may play a vital role in auditory perceptual and cognitive deficit mechanisms in schizophrenia. Overall this dissertation furthers current understanding of cortical representation of speech in complex listening environments and how auditory representation of sounds is affected in psychiatric disorders involving aberrant auditory processing.Item INTERACTIONS BETWEEN APPETITIVE AND AVERSIVE PROCESSING DURING PERCEPTION AND ATTENTION(2017) Padmala, Srikanth; Pessoa, Luiz; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Although understanding brain mechanisms of appetitive-aversive interactions is relevant to our daily lives and has potential clinical relevance, our knowledge about these brain mechanisms is rudimentary. To address this gap in the literature, we conducted two functional MRI studies that investigated appetitive-aversive interactions during perception and attention in healthy adult human brain. In the first study, we probed how potential reward signaled by advance cues altered aversive distractor processing during a subsequent visual task. Behaviorally, the deleterious influence of aversive stimuli on task performance was reduced during the reward compared to no-reward condition. In the brain, at the task phase, paralleling the observed behavioral pattern, significant interactions were observed in the anterior insula and dorsal anterior cingulate cortex, such that responses during the negative (vs. neutral) condition were reduced during the reward compared to no-reward condition. Notably, negative distractor processing in the amygdala appeared to be independent of the reward manipulation. During the initial cue phase, we observed increased reward-related responses in the ventral striatum, which were correlated with behavioral interference scores at the subsequent task phase, revealing that participants with increased reward-related responses exhibited a greater behavioral benefit of reward in reducing the adverse effect of negative images. Furthermore, the ventral striatum exhibited stronger functional connectivity with fronto-parietal regions important for attentional control. These findings contribute to the understanding of how potential reward influences attentional control and reduces negative distractor processing in the human brain. In the second study, we investigated brain mechanisms underlying the joint processing of positive and negative emotional information during a passive viewing task. Specifically we focused on probing the pattern of appetitive-aversive interactions in brain regions sensitive to the valence and salience of emotional stimuli. In a subset of regions that were sensitive to stimulus valence, competitive interaction patterns were observed. Notably, in other valence-coding regions such as the ventro-medial prefrontal cortex no evidence for competitive interactions was detected. Conversely, in regions sensitive to salience, cooperative interaction patterns were observed. The findings of competitive and cooperative type interactions supported contextual modulation of emotional processing in the human brain.Item THE INFLUENCE OF CONSCIOUS CONTROL OF MOVEMENT ON BRAIN PROCESSES AND THE QUALITY OF COGNITIVE-MOTOR PERFORMANCE(2015) Lo, Li-Chuan; Hatfield, Bradley D.; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The impact of mental stress on fine motor performance is typically maladaptive. The current research was conducted to investigate the manner by which state anxiety affects performance using a cognitive neuroscience perspective. The basic proposition tested, derived from the Reinvestment Theory and the Psychomotor Efficiency Hypothesis, is that stress introduces neuromotor noise to motor planning processes that translate as excess recruitment of motor units and degrade performance. Electroencephalography (EEG) was employed in Study 1 to assess regional cortical activation and cortico-cortical communication between non-motor associative and motor planning regions during the preparatory period of a dart-throwing task. The task was performed during stress (i.e., social evaluation, monetary incentives, and threat of electrical shock) and a relatively relaxed control condition through a within-subjects design. Regional activation was estimated from bilateral EEG recordings in the frontal, central, temporal, parietal, and occipital regions via spectral analysis to assess low-alpha and high-alpha band power to determine generalized arousal and task-relevant attentional focus, respectively. Cortico-cortical communication was estimated between all bilateral regions and the frontal motor planning area with particular emphasis on the left temporal (T3) to midline frontal (Fz) coherence. Elevated state anxiety was induced and associated with heightened T3-Fz EEG connectivity and synchrony of high-alpha band in the right occipital region. Based on these findings, Study 2 was conducted to determine the psychological processes accounting for the observed elevation in T3-Fz EEG coherence and the quality of muscle action during the throwing task. Specifically, participants employed an internal and an external attentional focus to perform the throwing task while their EEG and electromyography (EMG) were monitored. The use of internal focus, which is consistent with explicit monitoring of movement mechanics, was predicted to result in elevated T3-Fz EEG connectivity. This prediction was supported and, furthermore, the magnitude of connectivity was positively associated with motor unit activity assessed via EMG of four major muscle groups (i.e., flexor carpi ulnaris, extensor carpi radialis, biceps brachii, and triceps brachii). The evidence provided supports the theoretical notion that explicit monitoring promotes inefficient muscle activity, which mediates to impact performance negatively.Item Spatial cueing by a novel agent in preschool children and adults(2015) Terrizzi, Brandon; Beier, Jonathan S; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In the current study we assessed preschool children and adults' reflexive, covert spatial attentional response to a novel entity. In particular, we assessed whether covert attention was selectively engaged after construing the novel entity as an agent. Previous research has demonstrated that children and adults' covert spatial attention may be flexibly engaged by a non-directional cueing stimulus (e.g., a circle), however this attentional response is neither spontaneous nor is it reflexive (i.e., participants were told that the stimulus predicted the eventual target's location). For the first time we have shown that covert spatial attention is spontaneously and reflexively engaged by a morphologically unfamiliar cueing character when it is interpreted as an agent but not otherwise. The implication of this finding for theoretical accounts of the development of covert attention and agency attributions more generally are discussed.Item A Multi-Method Examination of Partitioned Pricing(2015) Abraham, Ajay Thomas; Hamilton, Rebecca W; Business and Management: Marketing; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation investigates the relationship between partitioned pricing (Morwitz, Greenleaf, and Johnson 1998) and dependent variables such as demand, preference, and attention. The first essay proposes a theoretical framework to examine extant and new moderators of partitioned pricing, classifying moderators based on the source of their impact as presentational, evaluative, or attentional. A meta-analysis of 17 years of research on partitioned pricing examines 149 observations from 43 studies in 27 papers (N = 12,878). The perceived benefit of the surcharge and the typicality of partitioning the surcharge in the category emerge as robust moderators of the effect of partitioned pricing on consumer demand. Surcharges for components perceived to provide high benefit and highly typical surcharges make partitioned prices more attractive. Replicating the meta-analytic effects of typicality, a follow-up experiment shows a more positive effect of partitioning on preference for typical surcharges than for atypical surcharges, and an eye-tracking experiment offers insight into the underlying mechanism by showing that people pay more attention to atypical surcharges than to typical surcharges. Different pricing strategies in the same market suggest different beliefs about the efficacy of partitioning prices on consumers' preferences. The second essay in this dissertation explores the impact of two countervailing theoretical influences that may predict how the numerical magnitude of surcharges can affect preferences. "Base price anchoring" suggests that as the magnitude of the surcharge increases (holding the total price constant), consumers may anchor on a lower base price, leading them to evaluate partitioned prices more favorably. In contrast, "surcharge salience" suggests that as the magnitude of the surcharge increases, attention to the surcharge increases, and evaluations of partitioned prices decrease. An analysis of eBay auction data reveals support for the influence of base price anchoring, and a follow-up experiment suggests that this mechanism dominates at lower levels of surcharge magnitude whereas surcharge salience dominates at higher levels of surcharge magnitude. Finally, an eye-tracking study demonstrates the influence of surcharge salience on preference and attention.Item The effect of mental stress on brain dynamics and performance related to attention control during a vigilance task: An electroencephalographic investigation(2013) Russell, Bartlett Anne Healy; Hatfield, Bradley D; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Anxiety can increase distractibility and undermine the quality of psychomotor performance. Models of attention processing postulate that anxiety consumes limited executive resources necessary for maintaining goal-oriented, "top-down" attention control and suppressing stimulus-driven "bottom-up" distraction. Attention Control Theory (ACT) predicts that anxiety adversely affects the efficiency, and particularly inhibitory components of executive, frontally mediated top-down attention control. We used two approaches for examining this model. First, though attention affects synchrony among neural structures, information regarding how human oscillatory patterns (measured with electroencephalography, EEG) change as state anxiety increases is limited. Second, while anxiety affects the balance between top-down and bottom-up mechanisms, to our knowledge no one has yet measured anxiety's effect on attention using a neural measure of top-down control in conjunction with more traditional bottom-up measures of attention capture (e.g., the P3 event related potential, or ERP). Purpose: Study 1 examines the oscillatory patterns (spectral dynamics) of the cortex in order to investigate whether frontal regions exhibit patterns of reduced efficiency and altered networking with posterior regions during threat of shock. In order to assess the relationship between top-down and bottom-up attention dynamics, Study 2 uses the same threat protocol to measure attention-directed top-down modulation of sensory signaling (steady-state visual evoked potential, or ssVEP modulation) and of bottom-up attention capture by discrete targets and distractors (Event Related Potentials, ERPs). Results: The spectral analyses in Study 1 suggest decreased processing efficiency and decreased frontal networking (coherence) with more posterior regions as anxiety increased. Reduced coherence, however, could indicate either increased or decreased top-down focus; Study 2 provides more insight. Neural responses to task-relevant targets (ERPs) diminished as threat increased, while responses to task-irrelevant distractors remained unchanged. Contrary to what ACT would predict, we observed an increase in attention modulation of an ssVEP frequency associated with amplifying the task-relevant signal and no change in an ssVEP associated with inhibiting task-irrelevant stimuli. These findings suggest top-down attention control increased under threat, but was not enough to prevent degraded processing of task-relevant targets coincident with reduced efficiency on task performance. Implications and suggestions for refining ACT are discussed.Item Infant speech perception in noise and early childhood measures of syntax and attention abilities(2008) Blayney, Elizabeth Sarah Sanford; Newman, Rochelle; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Childhood outcomes in syntactic and attention abilities were measured for 23 children (mean age = 5:3) who, as infants, had either succeeded or failed at identifying their name in the presence of multitalker background noise. Children from the unsuccessful infant group were rated by parents as having significantly more difficulty with attention-related behaviors than children from the successful infant group. The two groups did not perform significantly differently on standardized measures of morphosyntactic ability, but the unsuccessful group was found to have significantly lower MLUs on narrative language samples than the successful group.