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Abstract:
GOALS. Pseudoneglect refers to the leftward bias in perceived
line midpoint (i.e. point of subject equality, or pse) of normal
subjects in line bisection tasks. Left or right cues influence this
bias, promoting shifts in pse to the left and right, respectively.
Trapezoidal lines also influence pse, displacing it toward the
taller side. Two experiments test the hypothesis that the effect of
line geometry, like that of unilateral cues, results from an
exogenous recruitment of spatial attention. METHODS. Right-handed
subjects (N=58) participated in two experiments employing a
tachistoscopic forced-choice line bisection task. RESULTS.
Experiment 1 crossed the effects of cue position and cue contrast,
and the significant interaction between these factors confirms an
attentional locus of cueing effects on pse. Experiment 2 crossed
the effects of line geometry and cue position, revealing that both
factors significantly influence pse (p < .001), and possess a
significant interaction (p = .020). CONCLUSIONS. According to
Additive Factors Logic, the finding that spatial cueing interacts
with line geometry suggests that both variables exert influence a
common site of processing, and that line geometry influences the
spatial distribution of attention. An explanation for the
interaction is offered, based on a compressive nonlinearity that
maps attentional bias to perceptual error.
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