| Summary: | Deciding where to direct our gaze is one of the most ubiquitous decisions we make, and this process can be viewed as a competition between objects in the visual scene (Findlay & Walker, 1999). Here we investigated the decision making process involved in target selection, and the impact it has on saccade metrices and dynamics such as latency, landing position and trajectory. We manipulated the evidence available for selecting one target over another, by varying the motion coherence level in a random dot kinematogram (RDK). In chapter two, we investigated the quantity of evidence available, and the period over which it was accumulated, to ascertain the effect this had on eye movements. The results suggest that increasing the quality (motion coherence) of the evidence had a larger effect on saccade trajectories than increasing the quanity (duration) of the evidence, and that the last piece of evidence viewed has the largest impact. In chapter three the role of confidence was examined and we successfully dissociated confidence ratings from the evidence underlying the decision, suggesting that confidence is not based on the same neural structures which are involved in eye movement control.
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