Several experiments explored the possibility that motion-induced grouping would modulate the spatial distribution of the flanker compatibility effect (FCE). Subjects were required to make a speeded decision about a central target letter embedded in a five letter string. On each trial the identity of the near or far letters was either compatible or incompatible with the correct response while the remaing letters were neutral. In contrast to the findings of Driver & Baylis (1989), when the far distractors and the target moved together while the near distractors remained stationanry, the authors did not find that the FCE for the far distractors was greater than the FCE for the stationary near distractors. Moreover, the pattern of response latencies in this moving condition were not different from what was observed when all letters remained stationary. Accuracy was affected, but not in the direction predicted by the view that attention is directed to perceptual groups. Modulations of the distribution of attention in response to motion-induced grouping is not a robust phenomenon. Nevertheless, a simple spotlight model of attention is challenged by demonstrations in the literature that perceptual grouping mediated by static properties such as closure, colour and good continuation strongly influence the spatial distribution of the FCE and that the allocation of attention in search is strongly influenced by stimulus motion.
Abstract