Do fixational eye-movements actively and optimally sample the retinal stimulus? - WCUB, ENWW

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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