Stable individual differences predict eye movements to the left, but not handedness or line bisection.

When observers view an image, their initial eye movements are not equally distributed but instead are often biased to the left of the picture. This pattern has been linked to pseudoneglect, the spatial bias to the left that is observed in line bisection and a range of other perceptual and attentional tasks. Pseudoneglect is often explained according to the dominance of the right-hemisphere in the neural control of attention, a view bolstered by differences between left- and right-handed participants in both line bisection and eye movements. We re-examined this observation in eighty participants (half of whom reported being left handed) who completed a computerised line bisection task and viewed a series of images. We failed to replicate the previously-reported effect of handedness on eye movements in image viewing, with both groups showing a large average bias to the left on the first saccade. While there was a modest effect of handedness on line bisection, there was no correlation between the two tasks. Stable individual differences, as well as a shorter latency on the initial saccade, were robust predictors of an initial saccade to the left. Therefore, while there seems to be a reflexive and idiosyncratic drive to look to the left, it is not well accounted for by handedness and may have different mechanisms from other forms of pseudoneglect.
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