Abstract
Moving objects generate smeared images across retina creating a spatial signal, a motion streak. On the one hand, the motion streak provides direction information of motion and facilitates motion processing (Geisler, 1999). On the other, the motion smear is suppressed in our perceptual representation (Burr, 1980). Here, we hypothesized that the spatial signal of motion streak could further suppress the persistence of visual representation. In Experiment 1, we measured the effect of an artificial motion streak by adding a streak line to a moving dot along the trajectory and comparing the perceived blur length of moving dots with or without the artificial ‘streak’. With varied refresh rate (24 Hz to 1440 Hz), dots (without the artificial streak, radius: 0.1˚ ) and lines (with the artificial streak, length: 0.2 to 4˚ ) horizontally moved at a constant speed (60, 90, 120˚ /s). Participants were asked to report the length of concurrently perceived persisting images. Perceived length of line stimulus was shorter than that of dot stimulus (F(1,8)=21.48,partial_eta-squared=.695,p<.001). The difference in perceived length of two stimuli increased as refresh rate decreased or speed increased, evidenced by a significant interaction of the stimulus type with refresh rate (F(1,8)=12.21,partial_eta-squared=.601,p<.001) and speed (F(1,8)=8.87,partial_eta-squared=.445,p<.001). In Experiment 2, we adjusted the actual number of dots and lines from 1 to 4 and asked participants to report the physical length of the moving stimuli. We generated line stimulus by connecting dots to match the physical length with dot stimulus. Perceived length of line stimulus was shorter than that of dot stimulus (F(1,5)=7.676, partial_eta-squared=.734,p=.0393), and the difference in perceived length increases as the number of elements increases (F(2,10)=4.36,partial_eta-squared=.304,p=.044). Taken together, results suggest that an artificial motion streak generated by adding a line to a dot stimulus suppresses the visual persistence and shortens the perceived length of fast-moving stimuli.