Do fixational eye-movements actively and optimally sample the retinal stimulus? - WCUB, ENWW
Lead Research Organisation:
University of Oxford
Department Name: Interdisciplinary Bioscience DTP
Abstract
Fixational eye movements are small eye movements that occur during visual fixation. They are necessary to prevent fading of a visual stimulus, as fading is reported when a stimulus is stabilised on the retina by counteracting eye movements (eg. Martinez-Conde, Macknik, Troncoso, & Dyar, 2006; Riggs, Ratliff, Cornsweet, & Cornsweet, 1953). Thus, counterintuitively, movement is required to fixate on and see stimuli, as without these movements the perceptual world would continually fade to a featureless grey.
In my DPhil I want to investigate how fixational eye movements are influenced by the stimulus, i.e. whether certain qualities of the stimulus, such as size, luminance and shape, in relation to the individual photoreceptor mosaic of the observer, change the patterns of fixational eye movements. Fixational eye movements are known to display qualitative differences in different conditions (eg. Ditchburn & Ginsborg, 1953), but it is not known what drives this. This project will use an adaptive optics scanning laser ophthalmoscope (AOSLO) to extract fixational eye movements at single cone resolution and reference them to the photoreceptor mosaic. Unlike other current research into fixational eye movements, which is largely focussed on attentional effects, I am interested in testing whether fixational eye movements adapt to the stimulus and to the way in which that stimulus is sampled by the individual's photoreceptor mosaic, which is as unique as an individual's fingerprint. This project considers vision as an active process, whereby the movement of the eyes is a fundamental part of visual sensation (Findlay & Gilchrist, 2003).
BBSRC Priority Areas: Technology development for the biosciences, Brain Science and Mental Health
In my DPhil I want to investigate how fixational eye movements are influenced by the stimulus, i.e. whether certain qualities of the stimulus, such as size, luminance and shape, in relation to the individual photoreceptor mosaic of the observer, change the patterns of fixational eye movements. Fixational eye movements are known to display qualitative differences in different conditions (eg. Ditchburn & Ginsborg, 1953), but it is not known what drives this. This project will use an adaptive optics scanning laser ophthalmoscope (AOSLO) to extract fixational eye movements at single cone resolution and reference them to the photoreceptor mosaic. Unlike other current research into fixational eye movements, which is largely focussed on attentional effects, I am interested in testing whether fixational eye movements adapt to the stimulus and to the way in which that stimulus is sampled by the individual's photoreceptor mosaic, which is as unique as an individual's fingerprint. This project considers vision as an active process, whereby the movement of the eyes is a fundamental part of visual sensation (Findlay & Gilchrist, 2003).
BBSRC Priority Areas: Technology development for the biosciences, Brain Science and Mental Health
Organisations
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| BB/M011224/1 | 01/10/2015 | 31/03/2024 | |||
| 1810152 | Studentship | BB/M011224/1 | 01/10/2015 | 30/09/2019 |
| Description | The most important finding from my DPhil so far has been an improvement in research methods. I have developed a new way of identifying microsaccades (a type of very small eye movement) in binocular eye tracking data, which appears to work well on two separate data sets. The publication relating to this is currently under review after preliminary acceptance in abstract form into a special issue on microsaccades in the Journal of Eye Movement Research. My main experiment to date has shown that how stable we can keep our eyes is related to the eccentricity of visual stimuli - the further from the fovea (the area of the eye we use to focus with) a stimulus is presented, the more unstable our fixation is. There appears to be no strong link between spatial structure and fixational eye movement. We are currently exploring if the effect of eccentricity is related to our ability to detect motion. |
| Exploitation Route | My findings will inform the rest of my DPhil, as I am trying to contribute to our understanding of fixational eye movements. Other researchers in this field might benefit from my findings as well as clinicians who work with patients who have central vision loss. |
| Sectors | Healthcare,Other |