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Title: Investigating the effects of odours on perception using EEG and fMRI
Author: Cook, Stephanie
ISNI:       0000 0004 6422 5380
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2017
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Olfaction and emotion are tightly linked due to the close anatomical coupling of the two systems in the brain. As a result, odours provide an effective means of manipulating hedonic perceptions of other stimuli. This thesis set out to explore the neural mechanisms underlying such effects. Using ERP analysis and event-related fMRI, we investigated how pleasant and unpleasant odours affected hedonic evaluations of visual stimuli, and examined whether these effects were dependent on the timing of stimulus presentation, olfactory-visual congruency, and the focus of the rating task. We also explored bidirectional cross-modal effects of visual stimuli on odour pleasantness and intensity perception. We found that odours consistently modulated hedonic evaluations of faces, objects and flowers, and that these visual stimuli in turn affected odour pleasantness and intensity ratings, and respiratory patterns. Effects of odours on face perception were represented in mid- and late-ERP components. Simultaneous olfactory-visual stimulation and olfactory-visual congruency amplified such effects, particularly in the context of an unpleasant odour. fMRI data showed that activity in regions known as part of the brain's valuation system was related to subjective hedonic ratings, and was boosted by a pleasant odour context. This thesis concludes that odours exert robust effects on hedonic evaluations. Moreover, visual stimuli in turn influence odour perception. The resulting changes in neural activations and respiratory patterns are likely the result of an evolutionary adaptive mechanism responding to ecologically relevant cross-modal information. Effects of odours on hedonic evaluations are represented in mid- and late-ERP components and by activity in the brain's valuation system.
Supervisor: Stancak, A. ; Field, M. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral