Using fixation-related potentials to investigate cognitive processes
thesisposted on 2022-03-28, 17:41 authored by Peter De Lissa
The aim of this research program is to explore and develop a relatively new technique for measuring the neurological processing of naturalistic visual images. Fixation-related potentials (FRP) combine eye-movement recordings with electroencephalographic recordings (EEG) so that brain responses can be measured to points of interest within a whole ecologically valid stimulus (e.g., to eyes within a whole face, or to a word within an entire paragraph). The first paper reports an experiment that used FRPs to investigate the neurological processing of faces when subjects' eye fixations were directed to eyes and mouths within a whole face. This experiment revealed that neural activity to faces is modulated by point of gaze. The second paper presents the results of an experiment that used FRPs to examine the neurological processing of faces when subjects' eye fixations were free to roam freely within a whole face. This experiment revealed that early occipito-temporal activity associated with face processing (N170) is elicited upon presentation of a face, and is not present in subsequent fixations, supporting suggestions that this brain potential reflects a face-detection process. In the third paper, the focus of the research program shifts from faces to words. Specifically, it reports an experiment that tracked the development of neural responses to novel words as they were repeatedly presented within a paragraph. This experiment revealed that unfamiliar words elicit different neural activity compared to familiar words when read for the first time, but that upon subsequent encounters this difference is no longer apparent. The fourth paper provides a methodological review of the combination of the FRP technique, using the insights gained from the first three experiments in this research program to build upon the seminal literature utilising this new neurological technique.