Unwanted and distressing visual imagery is a persistent and emotionally taxing symptom characteristic of several mental illnesses, including depression, schizophrenia, and posttraumatic stress disorder. Intrusive imagery symptoms have been linked to maladaptive memory formation, abnormal visual cortical activity during viewing, gaze pattern deficits, and trait characteristics of mental imagery. Emotional valence of visual stimuli has been shown to alter perceptual processes that influence the direction of attention to visual information, which may result in enhanced attention to suboptimal and generalizable visual properties. This study tested the hypothesis that aberrant gaze patterns to central and peripheral image regions influence the formation of decontextualized visual details which may facilitate involuntary and emotionally negative mental imagery experiences following a stressful or traumatic event. Gaze patterns and hemodynamic response from occipital cortical locations were recorded while healthy participants (N = 39) viewed and imagined scenes with negative or neutral emotional valence. Self-report behavioral assessments of baseline vividness of visual imagery and various cognitive factors were combined with these physiological measures to investigate the potential relationship between visual perception and mental recreation of negative scenes. Results revealed significant effects of task and valence conditions on specific fixation measures and hemodynamic response patterns in ventral visual areas, which interacted with cognitive factors such as imagery vividness and familiarity. Findings further suggest that behaviors observed during mental imagery reveal processes related to representational formation over and above perceptual performance and may be applied to the study of disorders such as PTSD. / Ph. D. / Intrusive imagery describes the visual components of flashbacks that are common to mental disorders such as posttraumatic stress disorder (PTSD), obsessive-compulsive disorder, and schizophrenia. Several explanations for this symptom have been suggested, including incomplete memories, changes in visual brain structures and function, inappropriate viewing patterns, and an individual’s ability to imagine visual scenes in detail. The emotional tone of a scene has also been shown to affect viewing patterns, which may lead to attention being narrowly directed toward specific visual details while ignoring surrounding information. This study tested whether inappropriate viewing patterns to central and outer image regions in negative images influence narrow focus to emotional details, thereby allowing flashback-type imagery to occur following a traumatic or stressful event. Viewing patterns and blood flow in brain regions were measured while participants (<i>N</i> = 39) viewed and imagined scenes with negative or neutral emotional tone. Self-reported detail of voluntary mental imagery and other cognitive factors such as content familiarity and pleasantness were used to investigate a relationship between viewing and imagery of emotionally negative scenes. Results showed that certain cognitive factors as well as the type of visual task significantly affected particular eye movements and patterns of blood flow in visual regions of the brain. These measures interacted with cognitive factors such as imagery detail and content familiarity. Findings further suggest that behaviors observed during mental imagery reveal cognitive processes over and above those during viewing and may be useful in the study of disorders such as PTSD.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/86165 |
| Date | 05 June 2017 |
| Creators | Roldan, Stephanie Marie |
| Contributors | Psychology, Cate, Anthony, LaConte, Stephen M., Bell, Martha Ann, Diana, Rachel A. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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