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Abstract:
In previous studies of saccade curvature the influence of
task-irrelevant, and multisensory, distractors on trajectories have
been relatively ignored. We examined the impact of irrelevant
(experiment 1) and informative (experiment 2) visual, auditory and
tactile distractors on the trajectories of saccades to visual
targets. Observers made reflexive and voluntary saccades to visual
targets above and below fixation in the presence of visual,
auditory and tactile distractors which were located to the left and
right of fixation. Target and distractor stimuli were provided by
LEDs (visual), Piezo sounders (auditory) and linear actuators
(tactile) attached to a vertical stimulus framework: the fixation
stimulus (a cross within a diamond) was presented on a monitor
directly behind the framework. In experiment 1 target location was
indicated by target onset (reflexive) or a central arrow cue at
fixation (voluntary): distractor onset was simultaneous with
fixation point change or target onset. In experiment 2 the target
for voluntary saccades was determined by the distractor location
(e.g., if the distractor was on the right observers had to saccade
to the upper target and vice versa). In control trials observers
made reflexive and voluntary saccades to the target alone. We
observed that irrelevant distractors could influence saccade
trajectories. Further, both voluntary and reflexive saccades showed
evidence of curved trajectories but this effect was modified by
distractor modality. (Funded by Wellcome Trust, UK.)
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