Eye movements in time : auditory influences on oculomotor timing

The dominant models of eye movement timing consider only visual factors as modulators of when gaze orients (e.g. EZ-Reader, SWIFT, CRISP, LATEST). Yet realworld perception is multimodal, and temporal information from audition can both aid the predictive orienting of gaze (to relevant audiovisual onsets in time), and inform visual orientation decisions known to modulate saccade timing, e.g. where to orient. The aim of this thesis was to further the current understanding of eye movement timing to incorporate auditory information; specifically investigating the implicit and explicit capacity for musical beats to influence (and entrain) eye movements, and to quantify the capacity and limitations of direct control when volitionally matching eye movements to auditory onsets. To achieve this, a highly-simplified gaze-contingent visual search paradigm was refined that minimised visual and task factors in order to measure auditory influence. The findings of this thesis present evidence that self-paced eye movements are impervious to implicit auditory influences. The explicit control of eye movements, as small corrections in time to align with similarly timed music, was very limited. In contrast, when visual transitions were externally timed, audiovisual correspondence systematically delayed fixation durations. The thesis also measured the extent of direct control that can be exerted on eye movements, including the role of auditory feedback, as well as modulating visual complexity to further increase inhibition and temporal precision. These studies show a predictive relationship between the level of direct volitional control that an individual can affect and how synchronised they are. Additionally, these studies quantify a large subpopulation of quick eye movements that are impervious to direct control. These findings are discussed as provocation for revised oculomotor models, future work that considers the temporal relationship between shifts of attention and gaze, and implications for wider psychological research that employs timed eye movement measures