A great deal has been learned about the control of saccades by studying the influence of visual onsets that appear with the target stimulus. Such distractors can reliably modulate when a saccade is initiated, and these effects can be dissociated from the spatial modulation of where saccades land and the paths (or trajectories) of these movements. These behavioural effects depend on the spatial and temporal relationship between the saccade goal and competing distractor. Lévy-Schoen (1969) first reported an increase in saccade latency when two targets appeared simultaneously on opposite sides of fixation. We subsequently found that the latency increase, now known as the remote distractor effect (RDE), is maximal for near-simultaneous onsets and depends on distractor eccentricity, rather than the target-distractor spatial separation as might be expected. In addition distractors can modulate the trajectories of saccades with deviation towards and away from the distractor being observed. The distractor-related modulation of saccade trajectories is coarsely coded and can be related to the timing of when a saccade is initiated - with deviation away from a distractor emerging slowly over time. Over the past few decades much progress has been made in developing our understanding of these deceptively simple behavioural effects. Here I will provide an overview of some of these findings and the mechanisms proposed to account for them based on converging behavioural and physiological findings.
Robin Walker graduated from The University of Newcastle upon Tyne and went on to study for a PhD at the University of Durham (UK) under the supervision of John M Findlay and Andy Young. After a post-doc spent at Durham he went on to a work with Chris Kennard in London. He then joined the Department of Psychology at Royal Holloway, University of London in 1997 where he is now a Professor of Cognitive Neuroscience.
His earlier work involved studies of oculomotor distractor effects in normal populations and in people with cortical brain damage along with interests in visual field defects (hemianopia and macular disease). His recent work includes projects examining the oculomotor functions of the human superior colliculus using functional brain imaging techniques (fMRI). Current projects also include studies of reading dynamic scrolling text in people with a loss of central vision as well as in non-visually impaired individuals. This work has led to the development of an iPad app as a reading aid for people with macular disease.