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 A world without words: A non-lexicalist framework for psycho- and neuro-linguistics(2024) Krauska, Alexandra; Lau, Ellen; Linguistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In standard models of language production or comprehension, the elements which are retrieved from memory and combined into a syntactic structure are “lemmas” or “lexical items”. Such models implicitly take a “lexicalist” approach, which assumes that lexical items store meaning, syntax, and form together, that syntactic and lexical processes are distinct, and that syntactic structure does not extend below the word level. Across the last several decades, linguistic research examining a typologically diverse set of languages has provided strong evidence against this approach. These findings suggest that syntactic processes apply both above and below the “word” level, and that both meaning and form are partially determined by the syntactic context. This has significant implications for psychological and neurological models of language processing as well as for the way that we understand different types of aphasia and other language disorders. As a consequence of the lexicalist assumptions of these models, many kinds of sentences that speakers produce and comprehend - in a variety of languages, including English - are challenging for them to account for. In order to move away from lexicalism in psycho- and neuro-linguistics, it is not enough to simply update the syntactic representations of words or phrases; the processing algorithms involved in language production are constrained by the lexicalist representations that they operate on, and thus also need to be reimagined. This dissertation discusses the issues with lexicalism in linguistic theory as well as its implications in psycho- and neuro-linguistics. In addition, I propose a non-lexicalist model of language production, the “WithOut Words” (WOW) model, which does not rely on lemma representations, but instead represents that knowledge as independent mappings between meaning and syntax, and syntax and form, with a single integrated stage for the retrieval and assembly of syntactic structure. Based on this, the model suggests that neural responses during language production should be modulated not just by the pieces of meaning, syntax, and form, but also by the complexity of the mapping processes which link those separate representations. This prediction is supported by the results of a novel experimental paradigm using electroencephalography (EEG) during language production, which observes greater neural responses for meaning-syntax and syntax-form mapping complexity in two separate time windows. Finally, I re-evaluate the dissociation between regular and irregular verbs in aphasia, which has been used as supporting evidence for a distinction between the grammar and the lexicon. By training recurrent neural networks and measuring their performance after lesioning, I show that the observed clinical data can be accounted for within a single mechanism. By moving away from lexicalist assumptions, the non-lexicalist framework described in this dissertation provides better cross-linguistic coverage and aligns better with contemporary syntactic theory.Item An Examination of the Relationship Between Prior Musical Sophistication and Language Outcomes in People With Aphasia(2018) Fisher, Sarah J.; Faroqi-Shah, Yasmeen; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Research suggests there is a neural relationship between music and language, such that higher levels of musical sophistication may be positively correlated with a person’s linguistic and cognitive functioning. Though most of the research has focused on neurotypical individuals, the implication is that musical sophistication could benefit a person with a neurological impairment such as aphasia, perhaps by preserving linguistic abilities after the person has sustained a stroke. The study outlined here seeks to replicate and expand on the findings of Faroqi-Shah et al. (in prep) by looking at musical sophistication’s influence on aphasia severity as well as on specific language and cognitive domains (e.g., syntax, auditory processing, memory, and cognitive control). Knowing what specific domains of language or cognition are involved could help researchers better understand the neural location of musical and linguistic resources as well as the behavioral benefit of increased reserve in a neurologically impaired individual.Item The Cost of Turning Heads - The Design and Evaluation of Vocabulary Prompts on a Head-Worn Display to Support Persons with Aphasia in Conversation(2015) Williams, Kristin; Findlater, Leah; Geography/Library & Information Systems; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Symbol-based dictionaries could provide persons with aphasia a resource for finding needed words, but they can detract from conversation. This research explores the potential of head-worn displays (HWDs) to provide glanceable vocabulary support that is unobtrusive and always-available. Two formative studies explored the benefits and challenges of using a HWD, and evaluated a proof-of-concept prototype in both lab and field settings. These studies showed that a HWD may allow wearers to maintain focus on the conversation, reduce reliance on external support (e.g., paper and pen, or people), and minimize the visibility of support by others. A third study compared use of a HWD to a smartphone, and found preliminary evidence that the HWD may offer a better overall experience with assistive vocabulary and may better support the wearer in advancing through conversation. These studies should motivate further investigation of head-worn conversational support.Item An Investigation of Inhibitory Control in Bilingual Aphasia(2015) Sampson, Monica; Faroqi-Shah, Yasmeen; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Speaking involves selecting words and syntactic structures from among numerous competing options. It has been suggested that constant practice in using inhibitory control (IC) to limit within and cross-language competition may be associated with better lexical-semantic IC in proficient bilingual speakers relative to monolingual speakers. This advantage is also theorized to generalize to IC advantages in non-linguistic tasks (bilingual advantage hypothesis; BAH; Bialystok, 2001). However, conflicting evidence with regard to bilingual IC advantages abound, and the nature of relationship between linguistic and domain-general inhibitory control abilities is poorly understood. Since IC is proposed to be critical for lexical retrieval, it is important to understand the nature of IC engaged in individuals with lexical retrieval deficits (aphasia). Bilingual speakers with aphasia provide an ideal platform to examine the relationship between language processing and IC because there are seemingly contradictory effects at play: while bilingualism may render an IC advantage, acquired brain injury may be associated with less efficient IC. These contrasting effects allow one to tease apart the effects of bilingualism on IC, the domain generality of the bilingual IC advantage, and relationship between bilingualism, IC and lexical selection. It is important to examine these effects relative to matched monolingual controls to understand (i) if there is a bilingual advantage in lexically based IC and, (ii) the domain generality of any bilingual IC advantage. To address these aims, IC engaged in (i) lexical retrieval (semantically blocked cyclic naming task), (ii) linguistic processing (Stroop task), and (iii) non-linguistic processing (flanker task) was compared in ten each of bilingual (Tamil-English) and monolingual (English) neurologically healthy speakers and participants with aphasia. Results from neurologically healthy participants revealed a bilingual advantage in the blocked cyclic naming task (lexical IC) but no advantages in the non-lexical Stroop and flanker tasks. Results from participants with aphasia revealed no support for the proposed bilingual advantages in all three experiments. Furthermore, there was no significant association between inhibitory control measures in the three experimental tasks for all participants. Contrary to the predictions of the BAH, the collective results of this study indicate that there is insufficient evidence for the role of bilingualism in modulating non-lexical IC advantages. This lack of consistent support for BAH questions the influence of bilingual experience in modulating non-linguistic inhibitory control. These findings also reveal that the relationship between inhibitory control and lexical retrieval is not influenced by language background (monolingual versus bilingual) in persons with aphasia.Item Executive function in aphasia: is there a bilingual advantage?(2013) Baughman, Susan; Faroqi-Shah, Yasmeen; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Previous studies have demonstrated that there is a bilingual advantage in neurotypical populations on tasks of executive functions, particularly inhibition. However, little research has been conducted on a population with aphasia. This study examined whether bilingual persons with aphasia (BPWA) and monolingual persons with aphasia (MPWA) displayed any differences on tasks of executive functions. Four BPWA and four MPWA matched for age and Western Aphasia Battery subtest scores were administered a linguistic Stroop task, a nonlinguistic Stroop task, a trail-making task, and a non-verbal memory task. Results demonstrated that the two groups did not have significantly different scores on any of the tasks. While both groups of PWA were slower than neurotypical adults on reaction time measures, accuracy on all four tasks was unimpaired and within the normal range. These results, although preliminary given the small sample size and high performance accuracy, suggest that there may not be a clear "bilingual advantage" on tasks of executive function.Item Verb naming treatment for individuals with agrammatic aphasia: Efficacy data(2009) Graham, Lauren Elaine; Faroqi-Shah, Yasmeen; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Some individuals with aphasia present with agrammatism, which is characterized by short, syntactically ill-formed utterances and a paucity of verbs. These patients demonstrate marked difficulty with verb production both in confrontation naming and sentence production tasks. However, previous studies of syntax-based verb treatments have failed to show generalization to naming of untrained verbs. Therefore, the present study investigated the efficacy of a verb naming treatment that focused on purely semantic features of verbs. This research examined whether training semantic features of a verb class would facilitate within- and between-class generalization. Two male patients with agrammatic aphasia participated, with treatment aimed at training cut and contact verb classes. While only one participant (Participant B) improved in naming accuracy of trained cut verbs, neither participant displayed within-class generalization to untrained cut verbs. Only Participant B received training with contact verbs and demonstrated a trend of within-class generalization. Both participants improved on two standardized measures of aphasia performance, indicating that this treatment may have provided a generalized retrieval strategy for verb features. These results have implications for verb naming treatments, including stimuli-specific factors (i.e., number of verb features, verb frequency) and participant-specific factors (i.e., premorbid education, phonological vs. semantic deficit). Implications for future treatment research are also discussed.Item "Go aphasia!": Examining the efficacy of Constraint-Induced Language Therapy for individuals with agrammatic aphasia(2008-08-25) Virion, Christine; Faroqi-Shah, Yasmeen; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Recently, high intensity short-term therapy with a heavy emphasis on verbal language (called constraint induced language therapy, CILT) has gained momentum in aphasiology. However, the entire extent of its applicability and limitations has not been fully studied, especially with regard to specific aphasic deficits. This thesis sought to: 1) determine the efficacy of the originally published CILT protocol (o-CILT) with a deficit specific population (four individuals with agrammatic aphasia) and 2) examine the potential effect of a modified CILT protocol, which additionally focused on grammatical accuracy (g-CILT). Results revealed differences between the performance of individuals with agrammatism in this study and previously published CILT data. Findings also demonstrated that participants receiving g-CILT produced more significant gains on tests of aphasia severity and grammaticality, while individuals receiving o-CILT showed more highly significant changes on discourse measures of grammaticality. This paper suggests that, for individuals with agrammatism, CILT in its original form may not evince significant changes on tests of aphasia severity and grammatical production and a grammatical modification appears to increase the efficacy of CILT.Item A Voxel Based Approach to Identifying Lesion Sites in Aphasia: Comprehension and Production Deficits in Syntax, Semantics and Phonology(2007-08-20) Kling, Therese Danielle; Shah, Yasmeen; Braun, Allen; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The cortical regions of the brain traditionally associated with deficits of production and comprehension in language are Broca's and Wernicke's areas. Recent evidence suggests that other brain regions are involved and may be specific to linguistic areas of syntax, semantics and phonology. This paper describes the MRI results and language scores of 31 left hemisphere stroke patients with aphasia. Patients' lesions obtained from these MRI scans were reconstructed onto templates and entered into a voxel-based analysis program called Analysis of Brain lesion (ABLe) (Solomon, Raymont, Braun, Butman & Grafman, 2007) along with language scores. The results provided evidence for five key neuroanatomical regions of interest. These include the insula, the planum temporale, the operculum, the temporoparietal occipital (TPO) junction and the putamen. The results revealed common as well as unique areas of brain lesion for each of the behaviors.