Mental representations can be consciously experienced in mental imagery format, and verbal-linguistic format. Mental imagery representations of emotional information can evoke more powerful emotional responses than verbal-linguistic representations of the same information. Biases in mental imagery-based cognition are postulated to play a role in the maintenance of emotional disturbance in depression. Despite growing research, two questions remain: 1) is dysphoria (mild to moderate depression symptoms) associated with mood-congruent bias in the frequency of mental imagery generation; and 2) are such biases related to state emotional experience and emotional response to emotional information in dysphoria? To examine question one, participants varying in levels of dysphoria reported the occurrence of mental imagery in real time under task contexts that were emotional (negative and positive verbal cues) and unemotional (neutral verbal cues). Mental imagery generation was assessed under two task conditions: a) when participants were instructed to generate mental imagery in response to verbal cues (Study 1 & 2); and b) when participants were not instructed to generate mental imagery (or verbal-linguistic representations) during exposure to similar verbal cues (Study 2, 3, & 4). Results from all studies, across both instruction types, showed that dysphoria was associated with a loss of positive bias in mental representation generation, driven by reduced positive representation generation (Study 1, 2 & 4), but also by elevated negative representation generation (Study 1, 2 & 3). Interestingly, evidence of a loss of positive bias was most consistently observed when given neutral verbal cues, but also when given positive verbal cues. However, such dysphoria-linked effects were not disproportionately evident for mental imagery relative to verbal-linguistic representations, when both were allowed to naturally occur in Study 2, 3, & 4. Unexpectedly, dysphoria was associated with reduced tendency to generate negative imagery relative to negative verbal-linguistic representations in Study 2, though this finding was not replicated in Study 3 or Study 4. To examine question two, participants provided state mood ratings in addition to reporting mental representation occurrence during exposure to auditory emotional information (Study 3: verbal cues; Study 4: news stories). Dysphoria and mental representation generation was found to be unrelated to emotional response on negative trials (Study 3 & 4). However, greater occurrence of mental imagery, but not verbal-linguistic representation generation was related to greater positive emotional response on positive trials for individuals with dysphoria (Study 3), and all participants (Study 4). Study 5 analysed existing clinical trial data and found that the vividness of positive future event imagery is related to optimism in depression, such that those able to envision a brighter future are relatively more optimistic, and regain optimism more quickly, than those less able to do so, even when currently depressed. In summary, dysphoria was associated with loss of positive bias in mental representation generation, though such effects were not unique to imagery. Importantly, greater occurrence of mental imagery-based, but not purely verbal-linguistic, representations were associated with greater positive emotional response to positive information, and may hold value as a target for future translational research.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:725574 |
| Date | January 2017 |
| Creators | Ji, Julie |
| Contributors | Holmes, Emily ; Murphy, Fionnuala ; MacLeod, Colin |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://www.repository.cam.ac.uk/handle/1810/267883 |
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