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Little is understood about the origins of atypical scanpath formation in schizophrenia.  This thesis presents a series of novel investigations which aimed to characterise the viewing abnormality and its correlate in schizophrenia and to investigate a range of putative causal mechanisms. Individuals with schizophrenia and non-clinical comparison participants completed smooth pursuit and ocular fixation tasks, mood assessment scales and free-viewing of novel visual stimuli.  Patients also completed detailed clinical and neurophysical assessment. Results replicated findings of a ‘restricted’ style of visual scanning schizophrenia, characterised by reduced fixation and saccade frequency, increased fixation durations and reduced scanpath length.  Patients also demonstrated increases in medial saccade amplitude, duration and peak velocity relative to non-clinical viewers.  Viewing abnormalities were only minimally associated with clinical and demographic variables, occurred irrespective of the nature of the stimulus and conveyed high sensitivity and specificity in distinguishing cases from controls. Two studies manipulated attention to the viewing task in non-clinical viewers and patients respectively and suggested atypical scanning is not entirely attributable to diminished task engagement.   Restricted scanning was associated with both heightened anxiety and increased interference by irrelevant visual features during fixation.  A possible causal role of anxiety on distractibility and thus scanpath formation is tentatively proposed.  Restricted scanpaths were associated with dimensions of neurocognitive functioning including working memory, short term verbal memory and verbal fluency.  These patterns are argued to be consistent with a role of dysfunction of the dorsolateral prefrontal cortex in atypical scanpath formation.  Finally, scanpath dysfunction was found to occur independently of impairments in smooth pursuit performance, suggesting the independence of neuroanatomical bases for these deficits.

Selective attention is a filtering system that focuses on relevant information in our environment while irrelevant information is suppressed. The two well-known components of selective attention, facilitation and inhibition, work hand in hand to aid the processing of relevant information. The main theme of the present thesis was to study the inhibitory component of visual selective attention using stimuli such as motion and shape in a rapid serial visual presentation. Therefore, the first three experimental chapters investigated how relevant motion and shape information are processed and perceived in the presence of similar irrelevant information. The findings showed that first order visual motion detection is impaired in the presence of distracters and this inhibition of distracters is generated in a bottom-up manner. The findings were, however, not straightforward. The findings from Experiments 6-10 showed that distracter information (shape) influences shape target detection only when distracters are made salient and the perceptual load of the task is moderately difficult. Collectively, the findings in this present thesis suggest that there may be more than one kind of inhibition generated for different kinds of stimuli.

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Den här studien undersöker hur mikrokändisar presenterar sig själva på Instagram och vilka strategier för hur dessa mikrokändisar använder Instagram som är synliga. Studien analyserar bilder som publicerats av fyra svenska mikrokändisar under en månads tid. Netnografi används som insamlingsmetod och materialet analyseras med hjälp av en semiotisk text- och bildanalys. Teorier om självpresentation och attention economy används för att skapa en förståelse för hur de analyserade mikrokändisarna använder Instagram. Studien finner att mikrokändisarna presenterar sig själva som lyxiga och glamorösa. Strategier som de använder inkluderar att publicera bilder vid specifika tidpunkter, publicera bilder som ger ett intryck av att någon annan tagit bilden när de inte är medvetna om att bilden tas och tagga personer, platser, varumärken och inspirationskonton för att bli sedda av fler.

Unilateral Visual Neglect was measured in 12 Attention Deficit Disorder, Hyperactive elementary boys aged 8-12 years old, and 27 classroom derived boys also aged 8-12. Previous studies have suggested greater numbers of omission errors on the left side of the page in attention deficit disorder. This study compared a carefully diagnosed group of hyperactives to a classroom sample of boys to see if this type of error is particular to the ADD with H dimension of attention. The Behavioural Inattention Test (Thames Valley Test Company, (1987) series of conventional subtests, was used. This test is commonly used to detect neglect in stroke victims. Tests involve line bisection, line crossing, star and letter cancellation, representational drawing and copying of drawings. No significant differences between the two groups were found on non-parametric statistical testing of the results of four comparisons: total test score, total errors, left sided errors, right sided errors,. Some differences between the groups were noted, but scores realized were very close to the ceiling and few errors were made. It was concluded that the BIT test is not especially suitable for testing neglect in this population. / Graduate

Bipolar disorder is associated with significant social and occupational impairments, as well as increased risk for substance abuse and suicide. More research is needed to identify potential mechanisms associated with vulnerability to the disorder. Previous research has identified altered processing of emotional information in bipolar and bipolar-prone individuals, including attentional biases which appear to differ based on the current affective state of the individual. The current study applied a sensitive measure of attention (i.e., eye-tracking) to assess whether vulnerability to bipolar disorder, as indexed by hypomanic personality traits, would be correlated with biases in attention to emotional facial stimuli, independent of mood state. Hypomanic personality traits were hypothesized to be associated with greater attention to happy and angry faces, as indexed by faster initial orientation, more frequent gazes, and longer gaze duration for these stimuli. Participants completed self-report measures assessing current mood symptoms, positive and negative affect, and hypomanic personality traits. They then completed two tasks assessing attention for emotional faces. The first was an eye-tracking task, which measured latency to first fixation, total gaze duration and total number of gazes for each emotional face category. The second was a spatial cueing task which assessed both attentional engagement with emotional faces, and ability to disengage attention from this material. Hypomanic personality traits were significantly negatively correlated with latency to orient attention to happy faces. A trend toward decreased latency to orient to angry faces with higher hypomanic personality traits was also demonstrated. Hypomanic traits were not correlated with attention to sad faces. Furthermore, hypomanic traits were associated only with differences in initial orientation of attention, not with continued engagement or disengagement. The results of this study suggest that individuals with higher levels of hypomanic personality traits, who are hypothesized to be at greater risk of developing bipolar disorder, are characterized by differences in their initial orientation of attention to positive emotional stimuli, independent of their current mood state. This finding is indicative of biased information processing in individuals with vulnerability to bipolar disorder. Such a bias may have important clinical implications for individuals with a vulnerability to bipolar disorder, as it may represent a mechanism by which vulnerability leads to increased, and at times problematic, engagement with rewarding stimuli.

The purpose of this study was to functionally define and empirically test a model of psychological distress for mothers of children diagnosed with Attention-Deficit Hyperactivity Disorder (ADHD). This model delineates characteristics of the child, the parent, and the environment that may affect mothers' psychological symptomatology.

A dissertation presented in partial compliance with the requirements for the Master's Degree in Technology: Chiropractic, Durban Institute of Technology, 2003. / The purpose of this study was to evaluate the efficacy of Chiropractic Manipulative Therapy in the management of Attention Deficit Hyperactivity Disorder in children. / M

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.