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Areas of research interest

My research interests centre on basic issues of visual perception. I also have a strong interest in applied research that may have practical benefit. I have conducted research on brain plasticity and visual adaptation, as well as on sensory thresholds and cognitive effects on perception, including attention and arousal. Over the last 15 years, my research has focused on migraine and, more recently, photosensitivity, but my principal interest is in visual cognition, how it may become altered in any CNS disorder and the implications that has for the design of the visual environments in which people live.

The research on migraine and photosensitivity has explored changes in vision that exist in-between attacks (i.e. when people appear symptom-free). My approach is to use tasks that are reasonably well understood to explore competing theories of neuronal function in these conditions. I am particularly interested in visually induced migraine (who is affected, what characterises the visual stimuli that can induce migraine, what the underlying visual mechanisms are) and in the causes of visual discomfort (the illusions and discomfort people can experience when exposed to common migraine triggers, such as glare, striped patterns or flicker). Visual discomfort is frequently elicited in daily life. Glare can occur from interior lighting, daylight, or vehicle and road lighting at night. Computer screens, television and interior lighting can flicker. Regular arrays of fluorescent lights, escalator treads, window blinds, building decorations, some art in public spaces and fashion, often present high contrast, repetitive striped patterns.

Understanding the subtle changes in perception that exist in patient groups can inform our understanding of these conditions, with implications for their treatment. Raising awareness that features of the visual environment can have deleterious effects on people by eliciting discomfort or aggravating existing medical conditions is important as many of the problematic features are relatively easy to eliminate.

Dr Alex Shepherd