Abstract: Analogous to the physical momentum of objects in the real-world, visual memory for the final position of a moving target is usually displaced along its trajectory. Such displacement is referred to representational momentum. Several different approaches have been applied to interpret the representational momentum, which range from low-level perceptual processing to high-level cognitive mechanisms (Hubbard, 2010). An early approach tried to explain the displacement effect by cognitive factors dealing with principles of “internalized dynamics”. In addition to this cognitive approach, “low-level” explanations of representational momentum also have been proposed, suggesting that sensory factors play a decisive role. In particular, one plausible interpretation attributes the displacement effect to oculomotor action. In addition, it is possible that high-level information regarding physical principles contribute to the displacement by modulating eye movements (Hubbard, 2006b).
We hypothesize that if eye movements modulate or mediate the effects of such information on displacement, disrupting normal eye movement would interrupt the effective information. In the current study, three types of 3D balls (made of paper, wood or stone) rolled from left or right sides accompanied by sound corresponding to the ball material. In Experiment 1, subjects (22 college students) were instructed to indicate the stop position of the ball by pressing a button after tracking its movement for 1037ms and disappeared about 350ms. In Experiment 2, subjects (19 college students) were asked either to pursue the moving target until it disappeared or to track it till it stopped at the center of screen indicating by a “+”. The other procedures are similar to the Experiment 1. The subjects’ eye positions in both experiments were recorded by SMI Hi-Speed eye tracking system with sampling rate of 350Hz.
In Experiment 1, the forward shift in the direction of motion of the stone ball was larger than those of the wooden and paper balls’. There was a significant difference between the forward shift of the stone ball and wooden or paper ball. In addition, the oculomotor overshoot velocity of the stone ball was significantly faster than other two lighter balls’. In Experiment 2, when the oculomotor behavior was controlled, the forward shift in the trajectory and the oculomotor overshoot velocity were reduced compared to those in the eye tracking condition.
The present findings revealed that high-level cognitive factors (mass representation) modulate both oculomotor behavior and representational momentum. Meanwhile, representational momentum is also influenced by oculomotor overshoot. Our results suggest that high-level cognitive factors (mass representation) influence representational momentum by oculomotor-related information. Yet, representational momentum is also affected by many other factors. Our study provides new evidence that perceptual factor (oculomotor information) is not the only way to produce representational momentum.

Key words: representation, momentum, eye movements, oculomotor overshoot