Purpose. The perceived location of a flashed target and that of a moving target differed even when they are physically same. We investigated whether attention on the moving target plays any role in the phenomenon. Experiment. We used circular moving disks around the fixation point as moving stimuli. A flash stimulus was presented near to one of the disks (target) at a time about the middle of 4s disk rotation. The observer judged whether the flash was perceived ahead of or behind the target in terms of rotation angle. Repeating the judgement with controlling the flash location, the observer adjusted the flash angle to be aligned with the moving target (i.e., flash, target, and fixation point were to be collinear). The target disk was cued before the trial in one condition (cue condition) while no cue was presented in the other condition (no cue condition). To examine whether the knowledge of the target influences the flash lag effect, the amount of the flash lag was compared between the conditions. The number of the disks and the disk rotation speed were also varied. Results. Flash location was ahead of the moving target to be aligned perceptually in both the cue and no cue conditions. However, the amount of the difference from physical alignment location (lag effect) was larger in the no cue condition than in the cue condition. When the observer knew the target and tracked it, flash lag effect was smaller. Discussion. The results suggest that attending to the moving target reduces the amount of flash lag effect. Attentional states should be considered in interpreting flash lag effects.
ASJC Scopus subject areas
- Sensory Systems