Evaluating strategies for visual search and stimulus discrimination: implications for training eye-movements
Dewhurst, Richard Charles (2009) Evaluating strategies for visual search and stimulus discrimination: implications for training eye-movements. PhD thesis, University of Nottingham.
Eight experiments are described exploring the consequences of training eye-movements. Training is related to Findlay & Walker’s (1999) model of saccade generation, and consists of strategies for visual search and stimulus discrimination. These two components are separated in an effort to link training to the hypothesised Move and Fixate centres, respectively, within Findlay & Walker’s framework. Training directed towards the Move centre thus consistently improved visual search, and in Experiments 1-4 it was also shown that training directed towards the Fixate centre could further improve performance (in terms of target response discrimination) in an additive way over Move Training alone. Experiments 5-7 investigated the idea that training which promotes activity in the Move centre, independently, may actually be detrimental. This hypothesis draws upon the reciprocal inhibitory relationship between the Move and Fixate centres described by Findlay & Walker: training people where to look may increase activity in the Move centre and consequently hinder information processing during fixational eye movements, owing to an associated diminution of activity in the Fixate centre. Partial support for this conclusion was found. When training encouraged saccades away from a task-relevant centrally located stimulus, towards a visible saccade target in the periphery, there was evidence of premature disengagement when fixating, causing sub-optimal processing of the central stimulus in the first instance (Exp. 5). However, this effect was sensitive to changes in task (Exps. 6 & 7). This may explain why Move training did not encumber performance in a driving task (Exp. 8). Nevertheless, the findings reported herein have implications for training eye-movements in applied settings, because they suggest combined eye movement training directed towards the Move and Fixate centres in concert may produce cumulative performance gains, and offset detection failures associated with a sole emphasis on visual scanning.
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