Morsi, Anisa Yasmina;
(2023)
Variations in face perception across the visual field.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Face recognition is widely considered to be “special”, carried out in dedicated brain regions with distinct mechanisms compared to the recognition of other objects. Typically, low-level vision varies across the visual field in characteristic patterns, with our ability to see fine detail better along the horizontal vs. vertical meridian and in the lower vs. upper visual field. Given that faces appear to be processed uniquely, does face recognition vary across peripheral visual field locations in the same way? Using behavioural psychophysics, I uncover a clear advantage for face perception along the horizontal vs. vertical meridian, and a smaller-but-consistent advantage in the lower vs. upper field. Therefore, location influences face perception as it does in low-level vision. I then measured the retinotopic properties of three face-selective brain regions (the occipital face area, pFus and mFus), to determine whether visual field sampling within these regions could explain the variations in face perception. In all three areas there was a greater number of population receptive fields (pRFs) and better visual field coverage along the horizontal vs. vertical meridian and in the lower vs. upper field. These patterns resemble those observed in early visual cortex. Lastly, the process of localising and delineating face-selective areas of the brain was examined. Using novel functional localiser stimuli, I show that the delineation of face-selective brain areas, and the retinotopic properties subsequently measured from them, varies according to whether localiser stimuli were foveal or peripheral. Altogether, these findings demonstrate that the visual field anisotropies of low-level vision also affect high-level face recognition, with similar variations in retinotopic properties. This supports a hierarchical model of vision whereby spatial selectivity in higher-level areas is built upon the selectivity of lower regions, even within specialised face processing.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Variations in face perception across the visual field |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2023. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10182111 |
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