VictorJuiz/thesis huggingface dataset:
Electrophysiological Investigation of Feature-based Attention during Object Perception

We live in a visually rich environment yet our brains are only equipped to process a small fraction of all available information at any point in time. For successful and efficient perception, the brain relies on attention to differentiate and select specific stimuli for further analysis. Attention can be directed to features – feature based attention – which enhances the processing of other similar features independent of spatial location. I have recently shown that the benefits of feature-based attention not only apply to lower-level features, but also to processes of object perception. The aim of the thesis was to examine the behavioural and electrophysiological correlates underlying the influence of feature-based attention on object perception. Chapter 1 measured the electric field activity associated with attending to higher-level features (object contours) and comparing it with the neural activity while attending to motion stimuli. We found temporally later effects for contours relative to motion, suggesting that feature-based attention to objects might be mediated by higher-tier visual areas, such as the lateral occipital cortex. In Chapter 2, I describe a study designed to investigate the time course of neural activity while cueing attention within the feature dimension of shape that more directly targets higher-tier visual areas. Consistent with Chapter 1, I iii found temporally late modulation, but behavioural effects that were weaker than expected. To account for these findings, I proposed a “wrong-turn” model which explains the perceptual benefits and costs coupled to expecting the correct or incorrect feature by taking into consideration the hierarchical structure of the visual system. Moreover, the model also makes specific predictions about the pattern of behavioural and electrophysiological activity while attending to features of varying complexity during object perception. The aim of Chapter 3 was to test the predictions of the model; I cued attention to colour, a lower-level feature essential to perceiving the object. I found much stronger behavioural cueing effects, and a biphasic pattern (early and late) electric brain activity that confirmed the predictions of the model. Together the results indicate that feature-based attention plays an important role in object perception that is mediated by a flexible perceptual system.

Keywords: feature-based attention
object pereption, EEG
Advisor: Niemeier, Matthias
Social Cognition: Theory and Neuroscience in Fetal Alcohol Spectrum Disorders

Children with fetal alcohol spectrum disorders (FASD) have deficits across many cognitive, behaviour and social domains. However, despite social difficulty being proposed as a main deficit following prenatal alcohol exposure, the nature of their deficient social behaviour is largely unknown. One process that may underlie difficulties in social functioning is poor social cognition, which refers to one’s understanding of the self, others and social world. The primary goal of this dissertation was to determine whether social cognitive deficits represent a core disability underlying the socio-behavioural problems of FASD using a bottom-up approach. The first level of this approach is represented by face processing. Global and independent face feature processing was compared between FASD and normal controls (NC) using experimental and clinical measures. Eye gaze processing was investigated next using experimental and clinical tasks. At the highest level of the bottom-up approach, social perspective taking, including theory of mind and empathy were examined, along with how these abilities related to parent-rated behaviour. Finally, the lowest level consisted of specific aspects of the social neural network. White matter in three limbic pathways was investigated using diffusion tensor imaging (DTI). Results generally supported the bottom-up approach of social cognition in FASD. These children showed impaired processing of face features, when matching mouth shapes and partially occluded identity, compared with NC. The FASD group was slower to process gaze and arrow cues, suggesting impaired attention shifting. Children with FASD also showed impairments in social perspective taking, including understanding false beliefs and empathy, and these impairments were related to parent-rated attention and social problems, and autistic-like traits. Deficits in theory of mind got worse with age in FASD and empathy showed distinct sex-related differences. Although no group differences were observed on DTI indices, groups did show different age-related changes in white matter. In conclusion, deficits at each level of the current bottom-up approach may underlie the social impairments in FASD and may contribute to their broader social behavioural phenotype. The results from this dissertation have potential to inform clinical practice and lead to more effective diagnostic and treatment approaches in FASD.

Keywords: fetal alcohol spectrum disorders
social cognition
theory of mind
face and eye processing
Advisor: Rovet, Joanne
Rethinking the Political: Art, Work and the Body in the Contemporary Circus

This dissertation is about the circus, but it is also about how we think through a range of possibilities for individual and social change in the contemporary post-Fordist or neoliberal moment. In the last 40 years geographers, along side other scholars, have documented an increasingly close relationship between social, political, and economic aspects of life in western countries. These shifts have raised concerns over shrinking spaces of resistance and loss of counter hegemonic voices, and increased interest in transgressive or ‘outside’ spaces and bodies as sites of resistance, escape, and social change. Two contested sites that seem to offer promise for resistance, yet are simultaneously critiqued for their participation in dominant discourses, are art (or creative labour) and the body. Despite prolific literatures on these topics in geography in the last decade, links between creative labour, theories of embodiment, and the living practices of cultural workers are still far too rare. To address this I examine the intersection of theories of research, labour, art, discipline, embodiment and politics, understood through the daily practices of circus performers doing highly physical and embodied work. I focus in particular on clowns and aerialists, performance forms to which I have outstanding access as a performer in these genres. I addition to extensive participant observation over several years of performance work, my research is based on 26 elite interviews with key performers in the Canadian circus community, and an ephemeral archive of visual and textual materials. The resonance of questions about the nature of social research, art and work, and disciplined and fluid subjectivities, opens up new space for thinking across often-disconnected spheres. I believe the presence of circus performers’ lived experiences and my own embodied knowledge throughout this analysis deepens our understanding of political possibilities across many different spaces.

Keywords: embodiment
political
art
labour
work
circus
Advisor: Ruddick, Susan M.
Teacher Candidate Diversification Through Equity-based Admission Policy

This research responds to the problem of minority teacher under-representation within North America’s increasingly diverse urban school systems. It weaves together what is known about educational equity, teacher education admission policy, and policy implementation to explore the research question, “How did equity-based admission policy shape candidate diversification in an urban Canadian teacher education program?” The conceptual framework grounds this study within organizational culture and describes how culture both shapes and is shaped by interactions between structure and agency. The conceptual question asks, “How did institutional norms and individual will work to support or constrain equitable candidate diversification?” Data collection occurred during private interviews with members of three organizational groups: Policymakers, policy implementers, and policy beneficiaries. Policymakers were senior administrators with several years’ experience in their respective positions. Policy implementers were admission personnel, ad hoc faculty, and field-based educators. The policy beneficiaries were candidates who self-identified as future French and Physics teachers, and as members of Aboriginal, Disabled, Gendered/Invisible, and Racialized/Visible minorities. Data analysis was an iterative process of applying demographic, thematic, and editorial coding to the interview transcripts. Discussion highlighted several themes that shaped the admission process: External admission policy context, Faculty of Education Equity Policy, admission policy instrumentation, qualification precedence and weighting, academic qualifications, non-academic identity-based and experience-based qualifications, admission policy gaps, and last-minute Policy disclosure. It also addressed admission personnel recruitment, training, and performance during candidate personal information form assessment. Significant findings emerged in the areas of preservice program partnerships, candidate support services, qualification transparency, labeling of identity-based candidate characteristics, and admission personnel training. Research applicability extends to consecutive and concurrent teacher education programs, other tertiary professional licensing programs, and multi-site qualitative research projects. Recommendations for policy and practice target teacher education admission, policy implementation, and equity policy development.

Keywords: educational equity
teacher education admission policy
policy implementation
admission policy
Advisor: Bascia, Nina
The Effect of Liking on Recognition Memory for Music

Emotions can have important and powerful effects on cognitive processes. The emotional content of stimuli plays a role, as does the perceiver’s emotional response. Of particular interest here was whether subjective reactions (i.e., liking) to novel stimuli are related to subsequent memory performance. Although it is well established that memory influences liking, the present investigation sought to document whether the association is reciprocal, asking if liking influences memory. A series of five experiments examined whether liking is related to recognition memory for novel music excerpts. In the general method, participants listened to a set of music excerpts and rated how much they liked each one. After a delay, they heard the same excerpts plus an equal number of novel excerpts and made recognition judgments, which were then examined in conjunction with liking ratings. Across all five experiments, higher liking ratings were associated with improved recognition performance. This association was evident after a 24-h delay between the exposure and test phases (Experiment 2), when participants made liking ratings after recognition judgments (Experiment 3), when possible confounding effects of similarity and familiarity were held constant (Experiment 4), and when a deeper level of processing was encouraged for all of the excerpts (Experiment 5). The findings implicate the presence of a direct association between liking and recognition. Considered jointly with previous findings, it is now clear that listeners tend to like music that they remember, and to remember music that they like.

Keywords: Psychology
Memory
Music
Recognition
Advisor: Schellenberg, E. Glenn
Hiatus and Hiatus Resolution in Québécois French

This thesis is about vowel-vowel sequences across word boundaries in Québécois French (QF). QF has a number of phonological processes that seem motivated by hiatus avoidance, yet hiatus is tolerated in many instances as well. This research is about why hiatus is tolerated in QF, why it is avoided, and what grammatical models can account for the relevant processes. My work is intended as a contribution to the study of how best to account for variation and opacity within current grammatical models, and as a contribution to the study of the QF vowel system. The data are drawn from a corpus constructed from recordings of web extras for a Québécois reality television series. The data primarily come from a single speaker to ensure that any variation in the data truly represents intra-grammar variation, but data from other speakers are used as safeguard. Through the use of quantitative data as a means of investigating problems in theoretical phonology, the thesis is also meant to contribute to methodological discussions and discussions about the relationship between phonetics and phonology. I propose that the patterns of hiatus and hiatus resolution in QF are best modeled through three sets of constraints organized in a serial manner. This proposal is based on the claims that the data show evidence for an anti-hiatus constraint, for feature-based analysis, for stochastic modeling, and for multiple levels. The proposed model combines insights from Stochastic Optimality Theory (Boersma & Hayes 2001), multi-level Optimality Theory (Kiparsky 2000, 2010; Rubach 2000), and the Contrastivist Hypothesis (Dresher & Rice 2002, Dresher 2009, Hall 2007). Within the model, the first constraint set targets the smallest prosodic constituents and produces categorical outputs, the second applies to intermediate-sized constituents and can model optionality, and the third handles the largest prosodic constituents and produces complex patterns of variability.

Keywords: Phonology
Québécois French
Advisor: Dresher, B. Elan
Viewpoint Aspect in Inuktitut: The Syntax and Semantics of Antipassives

In many languages, antipassive morphology is comprised of aspectual morphology (Polinsky 2008). This thesis presents an analysis of the syntax and semantics of antipassives in Inuktitut by exploring the link between aspectual morphology and antipassive morphology. It resolves the longstanding question as to the factors governing the distribution of the antipassive morpheme, showing that the presence of the antipassive morpheme is determined by the meaning of the construction, i.e. it does not merely change the grammatical function. It is proposed that the antipassive construction has imperfective viewpoint in contrast to the ergative construction. Antipassive morphology is obligatory with punctual telic verbs, i.e. achievements, which are verbs that have perfective viewpoint by default. Antipassive morphology is thus necessary to convey imperfective viewpoint for verbs that are by default perfective. Using a modified Reichenbachian (Reichenbach 1947) framework, it is shown that imperfective viewpoint does not allow for telic interpretations. Instead, punctuality determines the types of viewpoint, which coincide with the aspectual meaning of the antipassive marker. Viewpoint contrasts in Inuktitut are encoded not only in morphology but in changes of case and agreement configurations. They are derived using a version of the Minimalist Program (Chomsky 2008). Imperfective viewpoint can either be default, in which case there is inherent case on the internal argument, or derived through the addition of antipassive morphology, in which case the construction closely parallels a nominative-accusative structure. Perfective viewpoint is encoded through absolutive case on the internal argument, either in an ergative construction or in a canonical intransitive construction with unaccusative verbs. The thesis provides insight into the relation between case-agreement configurations and aspectual contrasts in language and the nature of those aspectual contrasts. It also provides a new approach to the relation between lexical aspect and viewpoint by considering the role of punctuality.

Keywords: morphology
syntax
viewpoint aspect
punctuality
antipassive
aspectual contrasts
relation lexical and viewpoint aspect
semantics
Inuktitut
German
perfective
imperfective
Advisor: Johns, Alana
A Gene Regulatory Network for the Specification of Immunocytes in an Invertebrate Model System

Hematopoietic systems in vertebrates have been the focus of intense study. However immunocyte development is well characterized in very few invertebrate groups. The sea urchin is an attractive model for the study of immune cell development. Larval immunocytes, pigment cells and derivatives of the blastocoelar cells, emerge from a small population of precursors specified at blastula stage. Analyses from the genome reveal a complex system of immune receptors and effectors and a near complete set of homologues of vertebrate transcriptional regulators. Characterization of the expression profile and function of sea urchin homologues of key vertebrate hematopoietic transcription factors imply a conserved role in immunocyte development. SpGatac, an orthologue of the vertebrate Gata-1/2/3 transcription factors and SpScl, an orthologue of Scl/Tal-2/Lyl-1 transcription factors are both required for immune cell specification in the embryo. An important cis-regulatory mechanism that restricts SpGatac expression to the blastocoelar cells involves repression by SpGcm in the pigment cells. Characterization of the expression of several additional transcription factors, including SpE2A, an orthologue of vertebrate E2A/HEB/ITF2, SpId, an orthologue of the Class V bHLH factors that modulate E-protein function, and SpLmo2, an orthologue of the cofactor part of the transcriptional complex that includes Scl and Gata family members, suggests the existence of a conserved regulatory complex for hematopoiesis. Two isoforms of the SpE2A gene were identified. The shorter isoform shares genomic organization and sequence conservation with the mouse paralogue of E2A, HEBAlt. Expression of SpE2A and SpE2AAlt is consistent with a function in immunocyte development in the sea urchin embryo. Findings of the counterpart to a key vertebrate regulatory system functioning in the development of immunocytes in the simple sea urchin embryo lay the foundation for comparative immunocyte developmental gene regulatory network analyses. These will in turn lead to a greater understanding of the evolution of immune systems across phyla and will provide simple invertebrate model systems for detailed comparative investigations of regulatory function with direct relevance to vertebrates.

Keywords: development
immune cells
gene regulatory network
transcription
evolution
Advisor: Rast, Jonathan
Ben-David, Yaacov
Film Formation of Water-borne Polymer Dispersion: Designed Polymer Diffusion for High Performance Low VOC Emission Coatings

In this thesis, I describe experiments that were designed to provide a better understanding of polymer diffusion during latex film formation. This step leads to the improvement of film mechanical properties. Polymer diffusion in these films was monitored by fluorescence resonance energy transfer. Current paint formulations contain Volatile Organic Compounds (VOCs) as plasticizers to facilitate polymer diffusion. The drawback of this technology is the release of VOCs to the atmosphere. VOCs are deleterious to the environment and contribute to smog and ground level ozone formation. The propensity of water, an indispensible part of any latex dispersion, to promote polymer diffusion was studied. Copolymers of poly (butyl acrylate-co-methyl methacrylate) and poly(ethylhexyl acrylate-co-tertiary butyl methacrylate) with similar glass transition temperatures but different hydrophobicity were compared. Polymer diffusion was monitored for films aged at different relative humidities. Water absorbed by the hydrophobic copolymer film was less efficient in promoting polymer diffusion than in the hydrophilic polymer. Only the fraction of water which is molecularly dissolved in the film participate actively in plasticization. Although water has low solubility in most latex polymers, molecularly dissolved water is more efficient than many traditional plasticizers. The possibility of modifying film formation behavior of acrylic dispersions with oligomers was studied by synthesizing hybrid polymer particles consisting of a high molecular weigh (high-M) polymer and an oligomer with the same composition. Oligomers with lower molecular weight are more efficient as diffusion promoters and have less deleterious effect on high-M polymer viscosity. A different set of hybrid particles were prepared in which the oligomer contained methacrylic acid units. The composition of the oligomer was tuned to be miscible with the high-M polymer when the acid groups were protonated but to phase separate when the acid groups were deprotonated. At basic pH, these particles adopt a core-shell morphology, with a shell rich in neutralized oligomers. After film formation, the oligomer shell retarded polymer diffusion. This retardation is expected to expand the time window during which the paint surface can be altered without leaving brush marks (open time). Short open time is a pressing problem in current technology.

Keywords: Polymer Diffusion
Latex Dispersions
Film Formation
Volatile Organic Compounds (VOC)
Fluorescence Resonance Energy Transfer
Advisor: Winnik, Mitchell A.
Operating System Techniques for Reducing Processor State Pollution

Application performance on modern processors has become increasingly dictated by the use of on-chip structures, such as caches and look-aside buffers. The hierarchical (multi-leveled) design of processor structures, the ubiquity of multicore processor architectures, as well as the increasing relative cost of accessing memory have all contributed to this condition. Our thesis is that operating systems should provide services and mechanisms for applications to more efficiently utilize on-chip processor structures. As such, this dissertation demonstrates how the operating system can improve processor efficiency of applications through specific techniques. Two operating system services are investigated: (1) improving secondary and last-level cache utilization through a run-time cache filtering technique, and (2) improving the processor efficiency of system intensive applications through a new exception-less system call mechanism. With the first mechanism, we introduce the concept of a software pollute buffer and show that it can be used effectively at run-time, with assistance from commodity hardware performance counters, to reduce pollution of secondary on-chip caches. In the second mechanism, we are able to decouple application and operating system execution, showing the benefits of the reduced interference in various processor components such as the first level instruction and data caches, second level caches and branch predictor. We show that exception-less system calls are particularly effective on modern multicore processors. We explore two ways for applications to use exception-less system calls. The first way, which is completely transparent to the application, uses multi-threading to hide asynchronous communication between the operating system kernel and the application. In the second way, we propose that applications can directly use the exception-less system call interface by designing programs that follow an event-driven architecture.

Keywords: Operating Systems
Processors
Processor Caches
Multicore
Advisor: Stumm, Michael