FIGURE 1.

The flash lag illusion as a consequence of discrete sampling. Following the hypothesis of Schneider (2018), the visual system samples the visual scene, here a clock with rotating clock hand, during reoccurring intervals (“perceptual moments,” indicated by spaces between camera symbols). The end of these perceptual moments or “snapshots” (camera symbols) marks the registration of the stimulus position [the orientation of the clock hand and the flashed cue (red circle)]. The stimuli are registered at the last known position. This is always the correct position for the clock hand, since it is moving at a fixed speed and constantly updated, but not for the transient red cue since the presentation dates back in time, and instantaneous updating cannot occur. Hence, a systematic lag of the red cue is perceived, its magnitude depending on the relative onset between cue and snapshot (camera symbol). In Panel A the red cue is presented very early in the perceptual moment. The temporal distance between the cue presentation and the end of the snapshot is large, leading to a long perceived flash lag. In Panel B the red cue is presented very shortly before the end of the perceptual moment. A short amount of time passes until the stimulus position is registered, and the perceived flash lag is brief.