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<p>Emotions are pervasive in daily life, and a rich literature has documented how emotional stimuli and events disrupt ongoing processing and place heightened demands on control. Yet the executive control mechanisms that subsequently resolve that interference have not been well characterized. Although many failures of executive control have emotion at their core, numerous questions remain in the field regarding interactions between emotion and executive control. How do executive processes act on affective representations? Are emotional representations less amenable to control? Do distinct processes or neural networks govern their control? The present dissertation addresses these questions by investigating the neural systems and cognitive processes that support executive control in the face of interference from affective sources. Whereas previous research has emphasized the bottom-up impact of emotion on cognition, this dissertation will investigate how top-down executive control signals modulate affect's influence on cognition. Combining behavioral techniques with neuroimaging methodologies, this dissertation characterizes the interactive relationship between affective processes and top-down executive control and the ramifications of that interaction for promoting adaptive behavior.</p><p>Cognitive and behavioral phenomena related to affective interference resolution are explored in a series of research projects spanning attention and memory. Task-irrelevant affective representations may disrupt performance, but this interference appears to be dependent on top-down factors and can be resolved by executive mechanisms. Interference resolution mechanisms act on representations both of stimuli in the environment and information stored in memory. The findings reported here support emotion's capacity to disrupt executive processing but also highlight the role executive control plays in overcoming that interference in order to promote adaptive behavior.</p> / Dissertation

It has been assumed that the social deficits inherent in autism imply that individuals with the condition will be unable fully to appreciate the emotional content of music. My aim was to test this assumption, and to explore more widely the similarities and differences between the experience of music in the normal population and those with autism. My first study used musically-induced mood changes and a behavioural measure to show that music does indeed have a more than superficial effect on cognitive processes in a control group. The second study focused on high-functioning adults on the autism spectrum, using semi-structured interviews to investigate the part that music played in their everyday lives, concluding that autism is no bar to full appreciation of the emotional uses of music, though suggesting a degree of impoverishment in the language they used to describe the emotions. The final set of experiments compared control and autism group directly, using physiological (GSR) measures of arousal together with self-report of the emotions evoked by a set of musical items. Standardised questionnaires were used to measure alexithymia (difficulty in identifying and describing feelings) in individuals. Although the autism group experienced comparable levels of physiological arousal to music, they used fewer words than the control group to describe their emotional responses, a difference which correlated strongly with their level of alexithymia. My results are consistent with the hypothesis that in autism, the basic physiological and emotional component of their reactivity to music is functioning normally, but that their ability to translate these reactions into conventional emotional language is reduced, precisely in line with the extent of their alexithymia. These results suggest that the preserved ability of music to generate emotional arousal in autism may lead to clinical applications for the treatment of alexithymia in autism and other conditions.

Traumatic brain injury (TBI) is the leading cause of disability in young adults and a major public health problem. Persistent cognitive impairments are common, and constitute a significant source of long-term disability. The specific pathophysiological mechanisms underlying these impairments remain poorly understood. As it disconnects brain networks, white matter damage can be a key determinant of cognitive impairment after TBI. Neuroimaging and neuropsychological methods were employed to explore the relationships between indices of brain structure and cognitive function. The participants were 40 TBI patients and 40 healthy controls. First, relationships between focal lesions and cognitive performance were investigated using structural magnetic resonance imaging (MRI) and a battery of neuropsychological tests. The results demonstrated that lesion location and load are not good indices of the cognitive deficits - probably because diffuse axonal injury is poorly assessed by standard MRI. By contrast, diffusion tensor imaging (DTI) can be used to quantify the microstructure of white matter. A ‘whole-brain’ technique, tract-based spatial statistics (TBSS), was used to flexibly analyse the structure of white matter tracts. Despite only small amounts of focal damage observed using standard MRI, TBSS revealed widespread white matter abnormalities after TBI. White matter damage was found in patients with no evidence of focal damage, and in patients classified as ‘mild’ clinically. Relationships between white matter tract structure and specific cognitive functions were then explored. The structure of the fornix, an important white matter pathway of the hippocampus, correlated with verbal associative memory across the patient and control groups. By contrast, structure of frontal lobe connections showed distinct relationships with executive function in these two groups. The results emphasise the importance of white matter pathology after TBI and suggest that disruption to specific white matter tracts is associated with particular patterns of cognitive impairment, but also highlight the complexity of these relationships.

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<p> News organizations, non-profits, and even government agencies use information graphics to advertise and communicate their messages. Data visualizations are used heavily in these graphics, but they also often incorporate unusual design elements to help catch viewers&rsquo; eyes. In the struggle to rise to the top of the crowd, the data visualizations in infographics are often embellished with additions and modifications to the raw chart. The general consensus is that these embellishments can make charts less effective at communicating information, but most of them have never been tested to see if this is true. This work examines the factors in bar, pie, and donut charts that affect our perception of the charts.</p><p> I approach this in two different ways, both using a series of surveys on Mechanical Turk. The work on pie charts examines the individual contribution of arc-length, angle, and area variables so that embellishments may be evaluated based on their use of visual variables. The bar chart work examines some of the most common embellishments designers make to bar charts. This approach allows the isolated study of embellishments to determine which hinder or contribute the most to our perception of charts. I conclude with concrete recommendations based on the findings of the studies. My results show that conventional wisdom about how these charts are perceived is not always correct, and some types of embellishments are harmful while others have virtually no effect.</p>

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