Retrospective kappa effect: Attention can retrospectively distort the perception of time interval

Time perception is influenced by the spatial factors of visual stimuli. When observing a moving visual stimulus, a longer moving distance is judged to be longer than a shorter moving distance, even if the moving time is the same (the kappa effect). In the present study, to examine the effect of retrospective attention on the kappa effect, two visual stimuli with different moving distances were presented simultaneously. Immediately after these stimuli disappeared, the stimulus to which attention should be directed was specified. Participants judged the time interval to be longer when the stimulus to which they directed retrospective attention moved a longer distance than when it moved a shorter one. This finding indicates that stimulus features (distance moved) affect time perception by directing attention to a specific object in the memory after the disappearance of visual stimuli.