Mathew Hunter

• Diverse adaptive visual processing mechanisms allow us to complete simple discrimination and more complex visual search tasks in a wide visual photopic range (> 0.6 cd/m2). Despite extensive research ranging from the psychophysical to neurophysiological disciplines, none has examined how these processes behave in the scotopic and low - mesopic luminance ranges, even though we still utilize these processes daily albeit facing considerable decreases in performance. Characterization of perceptual and environmental limitations are needed. Furthermore, visual performance is often enhanced by innate visual - tactile mechanisms, and if patterned properly, application of additional tactile information could attenuate observed decreases in the low luminance spectral ranges. This dissertation will first demonstrate novel behavioural performance efficiency functions for visual discrimination and visual search as one traverses the scotopic to low - mesopic luminance ranges. Second, will demonstrate how various properties of tactile encoding can either attenuate behavioural deficiencies or even facilitate normal performance. Third, these results are supported from both behavioural (eye tracking) and neurophysiological (event related potential) analyses, isolating critical temporal gating windows with more efficient search patterns mediated via a central - parietal network.