Reflexive gaze orienting induces the line-motion illusion.

When a static line is presented near a brief cue, participants report motion within the line from the cued end towards the uncued end. Attention may mediate this effect by speeding the processing of the attended end of the line; however, apparent motion mechanisms between the cue and the line may also contribute. This study uses a new type of attentional cue, reflexive gaze orienting (RGO), which recruits attention automatically but uses a cue presented remotely from the line. Thus, RGO rules out motion mechanisms that might be recruited by a cue appearing in the vicinity of the line, and allows one to evaluate the contribution of attention per se to the illusion. In three experiments, RGO induced the line-motion illusion, establishing attention as a source of the illusion. Although attention may accelerate processing at the attended location, alternative mechanisms by which attention could cause the line-motion illusion are considered.