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Date
Publisher
Springer Nature
Abstract
In natural behavior, our eyes must coordinate two types of movements when looking between points
in space: conjunctive movements (where both eyes move together) and disjunctive movements (where
the eyes move in opposite direction to change their convergence angle). Here we investigate how
the initiation of these 2 different types of eye-movements is coordinated. We used the Size-Latency
effect to modulate saccadic latencies. To elicit combined saccadic and vergence eye-movements, we
displayed large ring targets at different vertical offsets and disparities relative to fixation. This allowed
us to easily dissociate version and vergence eye-movements. We found that saccadic latencies were
strongly modulated by the eccentricity of the targets as well as their hemifield, but not by the disparity
of the targets. The opposite was true for vergence: vergence latencies were modulated by the disparity
sign and amplitude of the targets, but not by their eccentricity or hemifield. We found a complete
lack of correlation between saccadic and vergence latencies, both across and within conditions.
Finally, we found that distributions of vergence latencies have a markedly reduced skewness as
compared to distributions of saccadic latencies, a hallmark of evidence accumulation. Overall, our
results demonstrate that the initiation mechanisms for these two types of eye-movements operate
independently.
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Except where otherwise noted, this item's license is described as Attribution 4.0 International