  In this paper, we consider the problem of visual scanning mechanism
underpinning sensorimotor tasks, such as walking and driving, in dynamic
environments. We exploit eye tracking data for offering two new cognitive
effort measures in visual scanning behavior of virtual driving. By utilizing
the retinal flow induced by fixation, two novel measures of cognitive effort
are proposed through the importance of grids in the viewing plane and the
concept of information quantity, respectively. Psychophysical studies are
conducted to reveal the effectiveness of the two proposed measures. Both these
two cognitive effort measures have shown their significant correlation with
pupil size change. Our results suggest that the quantitative exploitation of
eye tracking data provides an effective approach for the evaluation of
sensorimotor activities.
