Abstract
It is important to research driver's sensory function like movement of the eyes and the area which we can perceive an object during driving. Because we consider that it is useful of planning safety car, constructing a road etc In this paper, functional visual field during driving was measured experimentally In the case, the subject is given the additional loads about auditory or visually information the differentiation of the each functional vosuaI field was researched. As the results, if the subject was given the auditory and visually load at the same time, the functional visual field was the narrowest any other condition. In addition, relation between the degree of "image" transition which was defined by using optical flow vector. Broadness of functional visual field was considered There is a little correlative relation between these two features.
