In the Fr?hlich effect, the initial position of an object that suddenly appears in motion is perceived as being shifted in the direction of its motion. Here we establish that this shift is not an obligatory consequence of motion, but it is driven by focused attention. In href="#s2" class="sectionLink">Experiment 1href="#s5" class="sectionLink"> using different cueing conditions, we found that invalid cues produced larger perceptual shifts, although the Fr?hlich effect was still present for valid and neutral cues. These results support Müsseler and Aschersleben's (reveal-id="i1534-7362-17-1-3-musseler1" class="revealLink refLink">1998) proposal that the Fr?hlich effect is the result of the time it takes to shift focal attention to the moving stimulus. In href="#s3" class="sectionLink">Experiment 2href="#s5" class="sectionLink"> we found that the Fr?hlich effect increased when the valid cue arrived more than 100 ms after the start of motion, suggesting again that a delay in attention's arrival shifted the location of the perceived motion onset. In href="#s4" class="sectionLink">Experiment 3 we compare the motion-induced shifts when the subjects attended to a set of moving stimuli as a group and when they attended to an orientation singleton. We showed that Fr?hlich effect was only present when the target was individuated and disappeared when the stimulus was perceived globally. We conclude that the Fr?hlich effect is a predictive spatial shift produced and modulated by focal attention.
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