No description available.

Naming speed (NS) tasks that measure how quickly and accurately participants can name visual stimuli (e.g., letters) are commonly used to predict reading ability. However, the link between NS and reading is poorly understood. Three methods were used to investigate how NS relates to reading and what cognitive processes are involved: (a) changing stimulus composition to emphasize phonological and/or visual aspects (Compton, 2003); (b) decomposing NS times into pause and articulation components; and (c) analyzing eye movements during a NS task. Participants were in three groups: dyslexics (aged 9, 10), chronological-age (CA) controls (age 9, 10), and reading-level (RL) controls (aged 6, 7). We used a letter NS task and three variants that were either phonologically and/or visually confusing while subjects’ eye movements and articulations were recorded, and examined how these manipulations influenced NS performance and eye movements. For all groups, NS manipulations were associated with specific patterns of behaviour and saccadic performance, reflecting differential contributions of NS to reading. RL controls were less efficient, made more errors, saccades and regressions, and made longer fixation durations, articulation times, and pause times than CA controls. Dyslexics consistently scored in between controls, except for the number of saccades and regressions in which they made more than both control groups. Overall there were clear developmental changes in NS performance, NS components, and eye movements in controls from ages 6 to 10 that appear to occur more slowly for dyslexics. Furthermore, pause time and fixation duration were key features in the NS-reading relationship, and increasing visual similarity of the letter matrix had the greatest effect on performance for all subjects. This latter result was demonstrated by the decrease in efficiency and eye-voice span, increase in naming errors, saccades, and regressions, and longer pause times and fixation durations found for all subjects. We conclude that NS is related to reading via fixation durations and pause times; longer fixation durations reflect the greater amount of time needed to acquire visual/orthographic information from stimuli, and longer pause times in children with dyslexia reflect the greater amount of time needed to prepare to respond to stimuli. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2013-09-26 12:24:53.951

In this thesis, a model of motion integration is described which is based on a recursive Bayesian estimation process. The model displays a dynamic behaviour qualitatively similar to the dynamics of the motion integration process observed experimentally in smooth eye pursuit and plaid perception. The computer simulations of the model applied to smooth pursuit eye movements confirm the psychophysical data both in humans and monkeys, and the physiological data in monkeys. The temporal dynamics of motion integration is demonstrated together with its dependence on contrast, size of the stimulus and added noise. A new theoretical approach to explaining plaid perception has been developed, based on both the application of the model and a novel geometrical analysis of the plaid’s pattern. It is shown that the results from simulating the model are consistent with the psychophysical data about the plaid motion. Furthermore, by formulating the model as an approximate version of a Kalman filter algorithm, it is shown that the model can be put into a neurally plausible, distributed recurrent form which coarsely corresponds to the recurrent circuitry of visual cortical areas V1 and MT. The model thus provides further support for the notion that the motion integration process is based on a form of Bayesian estimation, as has been suggested by many psychophysical studies, and moreover suggests that the observed dynamic properties of this process are the result of the recursive nature of the motion estimation.

Previous research has shown L1 attrition to be selective (Gürel 2004) and often restricted to structures at the interfaces between syntax and context/pragmatics, but not to occur with syntactic properties that do not involve such interfaces (Interface Hypothesis, Sorace & Filiaci 2006). This is supported by many studies exploring cross-linguistic influence effects in interface structures, such as the production and/or interpretation of null versus overt pronominal subjects, not only in L1 attriters (Tsimpli et al. 2004, Montrul 2004) but also in other bilingual groups with different language combinations, such as early bilinguals (Paradis & Navarro 2003, Sorace et al. 2009), and advanced late bilinguals (Belletti et al. 2007, Rothman 2009). The current hypothesis is that individual L1 attrition affects only the ability to process interface structures but not knowledge representations themselves (Sorace 2011). In this thesis, we first compared a well-studied syntax-pragmatics interface phenomenon (pronominal subjects in Spanish) with a non-interface structure (the Spanish personal preposition a, also known as Differential Object Marking, DOM). In Spanish, the distribution of null and overt subject pronouns is pragmatically constrained, whereas the presence of the preposition just depends on the animacy and specificity of the direct object. Participants included a group of attrited speakers of L1 Spanish who had been living in the UK for a minimum of 5 years, and a group of Spanish monolinguals. Using a naturalness judgment task and eye tracking while reading, participants were presented with anaphoric sentences in which number cues matched or mismatched predicted antecedent preferences (i.e. null pronoun: subject preference; overt pronoun: object preference). The DOM study also used a mismatch paradigm, crossing preposition presence (al vs. el) with animacy, where an animate object requires the prepositional form al and an inanimate object requires the article el. Offline ratings revealed equal mismatch sensitivity for both groups of participants with both structures. However, eye-tracking measures showed that monolinguals were reliably more sensitive than attriters to the pronoun mismatch, while both groups showed equal on-line sensitivity to the DOM mismatch, which reveals that attrition affects interface structures, but not non-interface structures. Second, we investigated the effects of recent (re)exposure to L1 input on attrition. A second group of attriters carried out the same experiment after having been exposed exclusively to Spanish in a monolingual Spanish-speaking environment for a minimum of a week. Their eye-tracking results patterned with the monolingual group. This novel manipulation shows that attrition effects decrease as a result of L1 exposure, which reveals that bilinguals are sensitive to input changes and that attrition affects online sensitivity rather than causing a permanent change in speakers’ L1 grammatical representations.

Spontaneous speech is replete with disfluencies: pauses, hesitations, restarts, and less than ideal deliveries of information. Disfluency is a topic of interdisciplinary research with insights from psycholinguistics, phonetics and speech technology. Researchers have tried to determine: When does disfluency occur?, Can disfluency be reliably predicted to occur?, and ultimately, Why does disfluency occur? The focus of my thesis will be to address the question of why disfluency occurs by reporting the results of analyses of disfluency frequency and the relationship between disfluency and eye gaze in a collaborative dialogue. Psycholinguistic studies of disfluency and collaborative dialogue differ on their answers to why disfluency occurs and its role in dialogue. One hypothesis, which I will refer to as Strategic Modelling, suggests that disfluencies are designed by the speaker. According to the alternative view, which I will call the Cognitive Burden View, disfluency is the result of an overburdened language production system. Throughout this thesis, I will contrast these two theories for an ultimate answer to why disfluency occurs. Each hypothesis attaches a functional role to a structural definition of disfluency and therefore in order to determine why disfluency occurs, I will contrast the structural and functional characteristics of disfluency. I will attempt to do this by analysing the dialogue behaviour in terms of speech goals and eye gaze behaviour a speaker is engaged in when they make certain types of disfluencies. A multi-modal Map Task paradigm was used in this thesis, in which speakers were asked to describe the route on a cartoon map to a distant confederate listener who provided either visual or verbal feedback. Speakers were eye-tracked during the dialogue and a record was kept of when the speaker attended to the listener’s visual feedback. Experiment 1 tested the visual feedback paradigm to establish its validity as a baseline condition. Speakers were found to make more disfluencies when they could interact with the visual feedback, suggesting disfluency is more common in interactive circumstances. Experiment 2 added verbal feedback to the experimental paradigm to test whether listeners react differently to the two modalities of feedback. Speakers made more disfluencies when the feedback was more complicated. Structural disfluency types were also observed to fulfil different functions. Finally, Experiment 3 manipulated the motivation of the speaker and found that Motivated speakers gazed more often and were more disfluent per opportunity than Control speakers suggesting that highly motivated subjects are more willing to engage in difficult tasks.

Humans must regularly locate task-relevant objects when interacting with the world around them. Previous research has identified different types of information that the visual system can use to help locate objects in real-world scenes, including low-level image features and scene context. However, previous research using object arrays suggest that there may be another type of information that can guide real-world search: target knowledge. When a participant knows what a target looks like they generate and store a visual representation, or template, of it. This template then facilitates the search process. A complete understanding of real-world search needs to identify how a target template guides search through scenes. Three experiments in Chapter 2 confirmed that a target template facilitates realworld search. By using an eye-tracker target knowledge was found to facilitate both scanning and verification behaviours during search, but not the search initiation process. Within the scanning epoch a target template facilitated gaze directing and shortened fixation durations. These results suggest that target knowledge affects both the activation map, which selects which regions of the scene to fixate, and the evaluation process that compares a fixated object to the internal representation of the target. With the exact behaviours that a target template facilitates now identified, Chapter 3 investigated the role that target colour played in template-guided search. Colour is one of the more interesting target features as it has been shown to be preferred by the visual system over other features when guiding search through object arrays. Two real-world search experiments in Chapter 3 found that colour information had its strongest effect on the gaze directing process, suggesting that the visual system relies heavily on colour information when searching for target-similar regions in the scene percept. Although colour was found to facilitate the evaluation process too, both when rejecting a fixated object as a distracter and accepting it as the target, this behaviour was found to be influenced comparatively less. This suggests that the two main search behaviours – gaze directing and region evaluation – rely on different sets of template features. The gaze directing process relies heavily on colour information, but knowledge of other target features will further facilitate the evaluation process. Chapter 4 investigated how target knowledge combined with other types of information to guide search. This is particularly relevant in real-world search where several sources of guidance information are simultaneously available. A single experiment investigated how target knowledge and scene context combined to facilitate search. Both information types were found to facilitate scanning and verification behaviours. During the scanning epoch both facilitated the eye guidance and object evaluation processes. When both information sources were available to the visual system simultaneously, each search behaviour was facilitated additively. This suggests that the visual system processes target template and scene context information independently. Collectively, the results indicate not only the manner in which a target template facilitates real-world search but also updates our understanding of real-world search and the visual system. These results can help increase the accuracy of future realworld search models by specifying the manner in which our visual system utilises target template information, which target features are predominantly relied upon and how target knowledge combines with other types of guidance information.

El objetivo general de esta memoria es mejorar la metodología para identi car Website Keyobjects diseñada por Velásquez y Dujovne mediante el uso de herramientas Eye Tracking y algoritmos de Web Mining. Dado un sitio web, esta metodología toma como entrada el registro de peticiones (web log) del sitio, las páginas que lo componen y el interés de los usuarios en los objetos web de cada página, el cual es cuanti ficado a partir de una encuesta que permite medir la atención prestada por los usuarios sobre los objetos. Luego los datos son transformados y pre-procesados para finalmente aplicar algoritmos de Web Mining que permiten extraer los Website Keyobjects. Considerando lo anterior, en este trabajo de memoria se sugiere una forma distinta de cuanti ficar el interés de los usuarios sobre los objetos web, utilizando una tecnología de rastreo ocular (Eye Tracking), con el objetivo de prescindir de la encuesta, ocupar una herramienta de mayor precisión y así mejorar la clasi cación de los Website Keyobjects. Para comenzar, se investigaron las distintas técnicas y herramientas de rastreo ocular. Se optó por ocupar un Eye Tracker que ocupa la técnica más avanzada en su campo, la que ilumina los ojos con luces infrarojas y captura sus movimientos según el brillo de la pupila y el reflejo de la córnea, todo esto basado en vídeo. Luego se diseñó un experimento que permitiera establecer si se produce una mejora en la clasi cación de los objetos al ocupar distintos valores del interés de los usuarios: medido según una encuesta o un Eye Tracker. Se concluyó que la tecnología Eye Tracking es sumamente útil y precisa a la hora de conocer que es lo que mira un usuario y, por lo tanto, que es lo que más captura su atención. Además que el integrar esta tecnología a la metodología permite no realizar una encuesta, con lo que se evitan situaciones donde es altamente posible ingresar errores de forma involuntaria. Finalmente se estableció se produce una leve mejora, entre un 5 % y 6 %, en la metodología al ocupar la información generada por el Eye Tracker.

Ingeniera Civil Industrial / Bajo un contexto de compras y ventas, los procesos de decisión comienzan desde el momento en que una persona adquiere información sobre algún producto o servicio que se tenga interés en adquirir. De esta manera, la forma en la que se recopila la información, los juicios y las razones de cada consumidor que influyen en la toma de decisión, son interesantes de estudiar porque permiten comprender parte del comportamiento individual de los consumidores. Cuando un consumidor se ve enfrentado a una decisión, tiene múltiples caminos a seguir para dar con alguna elección. Estos caminos suelen estar condicionados por las preferencias y los gustos de los tomadores de decisión, y son denominados como reglas de decisión. Por lo tanto, las reglas de decisión son un conjunto de condiciones bajo las cuales se puede elegir o rechazar una determinada alternativa. Conocer las reglas de decisión que utilizan los individuos puede ser de gran interés para los investigadores porque, de esta forma, se podría predecir las futuras elecciones de los consumidores. Hasta el momento, los estudios relacionados a comprender los procesos de decisión han combinado diversas técnicas del tipo cualitativas y cuantitativas. En particular, esta investigación utiliza técnicas cuantitativas para poder comprender, diferenciar y predecir el comportamiento de individuos que participaron en dos experimentos de simulación de compras. Los experimentos mencionados, simulan la oferta de un producto (o servicio), en donde los participantes deben escoger una alternativa. Durante estos procesos de elección, los individuos utilizan herramientas de Eye tracking, las que permiten registrar todo el comportamiento visual. Esta información adicional es la base de este trabajo de investigación y su importancia radica en que permite comprender qué es lo que buscan los participantes y el camino recorrido para dar con su elección a través de la información visual. A partir de los datos visuales recopilados del primer experimento, se construyen modelos matemáticos que permiten predecir el tipo de regla de decisión usada por los encuestados, acertando en el 95\% de los casos. Las restricciones impuestas en los modelos utilizados para esta predicción, configuran un escenario ideal que no representa correctamente una situación real. Por este motivo se realiza un análisis sobre los datos del segundo experimento, en cuyo caso se busca predecir la alternativa elegida por los encuestados, lográndolo correctamente en un 61\% de los casos. En función de estos análisis, se demuestra que la información visual puede ser muy útil para entender el comportamiento de los consumidores. Finalmente, se propone para futuras investigaciones, adaptar los modelos aquí propuestos, incluyendo nuevas variables que permitan acercar el estudio a un escenario cada ves más real.

Ingeniera Civil Industrial / El estudio de la forma en la que el consumidor toma decisiones de compra es de vital importancia en marketing. Los equipos de marketing necesitan entender lo que valora el consumidor al momento de elegir un producto o servicio y por qué lo valora, para enriquecer el producto de acuerdo a sus gustos y mejorar la manera de exponer informaciones sobre el producto. En las técnicas usuales de análisis conjunto, se analizan las decisiones del consumidor frente a elecciones diseñadas por el investigador para deducir sus preferencias y gustos en los distintos atributos de un producto e inferir sus elecciones futuras. Esta memoria busca predecir no sólo la elección sino también la regla de decisión, utilizando los movimientos de ojos del consumidor durante el proceso de elección. En particular, se estudia la regla conjuntiva, no-compensatoria, en la cual se definen niveles mínimos aceptables para cada atributo. Las alternativas cuyos niveles sobrepasan estos niveles mínimos para todos los atributos son satisfactorias. El estudio se desarrolla con datos de un experimento de análisis conjunto en el cuál se pidió a los participantes seguir distintas reglas conjuntivas, que varían por sus distintos niveles mínimos aceptables. Luego de un análisis descriptivo del comportamiento visual de los participantes, se elaboran distintos modelos a partir de los datos de eye tracking. Estos modelos logran predecir la regla conjuntiva usada con una tasa de acierto de 88% y elecciones futuras con una hit rate de 75%, con 10 preguntas de entrenamiento. Se compara el desempeño de este enfoque con modelos que usan elecciones pasadas, que arrojan una tasa de 100% en la predicción de la regla usada con el mismo conjunto de entrenamiento. Finalmente, se aplican los modelos a un segundo experimento en el cual los participantes eligieron de manera libre, sin regla impuesta. Se logra predecir elecciones futuras con elecciones pasadas con una hit rate de 57% y con el movimiento ocular con una hit rate de 36%. Resulta que el hecho de agregar información de movimientos de ojos a los modelos que usan elecciones pasadas no mejora su desempeño. Se concluye que el comportamiento visual, si bien es consistente con las elecciones de un consumidor, no aporta más información acerca de su regla de decisión conjuntiva. Se propone, para futuras investigaciones, integrar el modelo con otros que suponen otras reglas de decisión, para abarcar la diversidad de reglas usadas en la realidad.

<p>Once thought to be predominantly the domain of cortex, multisensory integration has now been found at numerous sub-cortical locations in the auditory pathway. Prominent ascending and descending connection within the pathway suggest that the system may utilize non-auditory activity to help filter incoming sounds as they first enter the ear. Active mechanisms in the periphery, particularly the outer hair cells (OHCs) of the cochlea and middle ear muscles (MEMs), are capable of modulating the sensitivity of other peripheral mechanisms involved in the transduction of sound into the system. Through indirect mechanical coupling of the OHCs and MEMs to the eardrum, motion of these mechanisms can be recorded as acoustic signals in the ear canal. Here, we utilize this recording technique to describe three different experiments that demonstrate novel multisensory interactions occurring at the level of the eardrum. 1) In the first experiment, measurements in humans and monkeys performing a saccadic eye movement task to visual targets indicate that the eardrum oscillates in conjunction with eye movements. The amplitude and phase of the eardrum movement, which we dub the Oscillatory Saccadic Eardrum Associated Response or OSEAR, depended on the direction and horizontal amplitude of the saccade and occurred in the absence of any externally delivered sounds. 2) For the second experiment, we use an audiovisual cueing task to demonstrate a dynamic change to pressure levels in the ear when a sound is expected versus when one is not. Specifically, we observe a drop in frequency power and variability from 0.1 to 4kHz around the time when the sound is expected to occur in contract to a slight increase in power at both lower and higher frequencies. 3) For the third experiment, we show that seeing a speaker say a syllable that is incongruent with the accompanying audio can alter the response patterns of the auditory periphery, particularly during the most relevant moments in the speech stream. These visually influenced changes may contribute to the altered percept of the speech sound. Collectively, we presume that these findings represent the combined effect of OHCs and MEMs acting in tandem in response to various non-auditory signals in order to manipulate the receptive properties of the auditory system. These influences may have a profound, and previously unrecognized, impact on how the auditory system processes sounds from initial sensory transduction all the way to perception and behavior. Moreover, we demonstrate that the entire auditory system is, fundamentally, a multisensory system.</p> / Dissertation