The role of attention in motion extrapolation: Are moving objects 'corrected' or flashed objects attentionally delayed?

Objects flashed in alignment with moving objects appear to lag behind [Nijh awan, 1994 Nature (London) 370 256-257]. Could this 'flash-lag' effect be d ue to attentional delays in bringing flashed items to perceptual awareness [Titchener, 1908/1973 Lectures on thp Elementary Psychology of Feeling and Attention first published 1908 (New York: Macmillan); reprinted 1973 (New Y ork: Arno Press)]? We overtly manipulated attentional allocation in three e xperiments to address the following questions: Is the flash-lag effect affe cted when attention is (a) focused on a single event in the presence of mul tiple events, (b) distributed over multiple events, and (c) diverted from t he flashed object? To address the First two questions, five rings, moving a long a circular path, were presented while observers attentively tracked on e or multiple rings under four conditions: the ring in which the disk was f lashed was (i) known or (ii) unknown (randomly selected from the set of fiv e); location of the flashed disk was (i) known or (ii) unknown (randomly se lected from ten locations). The third question was investigated by using tw o moving objects in a cost-benefit cueing paradigm. An arrow cued, with 70% or 80% validity, the position of the flashed object. Observers performed t wo tasks: (a) reacted as quickly as possible to flash onset; (b) reported t he flash-lag effect. We obtained a significant and unaltered flash-lag effe ct under all the attentional conditions we employed. Furthermore, though re action times were significantly shorter for validly cued flashes, the flash -lag effect remained uninfluenced by cue validity, indicating that quicker responses to validly cued locations may be due to the shortening of post-pe rceptual delays in motor responses rather than the perceptual facilitation. We conclude that the computations that give rise to the flash-lag effect a re independent of attentional deployment.