Detection without awareness: an investigation of implicit change detection using combined EEG and fMRI

Scrivener, C. (2020) Detection without awareness: an investigation of implicit change detection using combined EEG and fMRI. PhD thesis, University of Reading. doi: 10.48683/1926.00108767

Abstract/Summary

The failure to detect differences between visual scenes is known as change blind�ness. When changes to an image are disrupted in some way, for example by a distractor screen or eye movement, we are often blind to any differences. It was once assumed that change detection is dichotomous; we either see a change, or we don’t. However, the presence of a change can influence our behaviour, even in the absence of full conscious report. It may be possible for us to sense that a change has occurred, even if we cannot specify exactly where or what it was. Using electroencephalogram (EEG), functional magnetic resonance imaging (fMRI), and behavioural measures, we found multi-modal evidence to suggest that sensing a change is distinguishable from being blind to it. In EEG, the late positivity potential, N2pc, and N1 amplitudes were larger for sense trials compared to blind. Additionally, a range of visual (BA18), parietal (BA40), and midbrain (anterior cingulate) areas showed increased fMRI BOLD activa�tion when a change was sensed. These visual and parietal areas are commonly implicated as the storage sites of visual working memory, and we therefore ar�gue that sensing may not be explained by a lack of representation of the visual display. In addition, we compared the EEG recorded inside and outside of the MRI scanner to investigate the influence of the MRI environment. Increased amplitudes were identified in the visual N1 in combined EEG-fMRI data, and almost all peak latencies were reduced. Based on our experience with EEG�fMRI data, we provide a guide for researchers considering combined recording and suggest when simultaneous EEG-fMRI may or may not be necessary.

Item Type	Thesis (PhD)
URI	https://reading-clone.eprints-hosting.org/id/eprint/108767
Identification Number/DOI	10.48683/1926.00108767
Divisions	Life Sciences > School of Psychology and Clinical Language Sciences
Date on Title Page	July 2019
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