Less attention and more perception in cued line bisection

Two experiments tested whether bias in cued line bisection resulted from perceptual grouping or attentional factors. Before trying to bisect a line, subjects had to report two lateralized letters. These cues were either equally spaced (Experiment 1) or asymmetrically spaced (Experiment 2) with respect to the line. No effect of order of cue-report on performance was found, arguing against the role of attentional factors. Bisection was systematically biased toward the closer-spaced cue. These findings in normal subjects suggest that cuing effects are due to perceptual rather than attentional factors.