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Title: Salience across chromoluminance space
Author: Hardman, Amanda
ISNI:       0000 0004 7967 6766
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2019
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Most researchers agree attentional selection occurs through direction of attention towards the most 'salient' (i.e. 'attention-grabbing') point of the visual field. Some researchers propose that salience is computed in extrastriate visual cortices and is dependent on all visual features summed linearly, but with different 'weights' given to the different visual features. Others believe it is computed in the striate cortex and is dependent on only the feature with the highest salience. This thesis investigated attentional salience in chromoluminance space. It aimed to determine: (1) which colour representations drive attentional selection; (2) how attentional selection differs for isolated and combined colour and luminance signals; (3) whether the impact of the attentional selection 'subprocesses' of target selection and distractor suppression is different for colour, luminance and both presented in conjunction and (4) which spatial properties affect the perceived contrast, and, therefore, salience, of chromatic stimuli. Through combined EEG and behavioural methods, it was shown that attentional selection is different between colour-isolating and luminance-isolating and colour-luminance combination stimuli. This indicates both that attentional salience of colour is driven by higher-level colour representations and that attentional selection is dependent mainly on the higher-salience feature dimension but on non-linear summation of dimensions when they are of similar strengths. It was also demonstrated, however, that attentional selection processes and perceived salience are affected by the presence of shared target/distractor feature dimensions as well as which colours are used and the level and distribution of contrast within a stimulus. Thus, researchers should be wary of generalising the results of specific paradigms and stimuli into overall models of attentional selection. In conclusion, non-linear processing of combined colour and luminance signals also impacts on their attentional selection. Stimulus salience varies between different colours and contrast distributions and is thus defined by both spatial and chromoluminant properties of the stimulus.
Supervisor: Martinovic, Jasna ; Sahraie, Arash Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Vision ; Visual fields ; Attention ; Electroencephalography