The amount of information available in the car is increasing. A contributory cause is the introduction of different driver support systems. These Intelligent Transport Systems (ITS) are often designed to display visual information, meaning that they address the human sense most occupied during driving. The additional visual information can reduce traffic safety by increasing the load on the driver and/or by causing divided attention and distraction. Besides consideration of the amount of information, alternative ways of presenting the in-car information are also needed. Visual information presented in the car, including the use of Head-Up displays (HUDs), is still assumed to be acquired via central vision, i.e. via fixation. The main advantage of HUDs being reduced changes of fixation and thus reduced acquisition times. A recent suggestion is that the load imposed on the driver can be reduced if the information acquisition is distributed between central and peripheral vision. This could be achieved by presenting in-car information in the peripheral field of view, provided that the information is designed so the driver can acquire it without shifting the focus of attention from the forward field of view. To our knowledge only the VISOR-prototype for navigation support is based on this idea for road vehicles, although military aircraft have used peripheral vision displays for many years. From the literature it is obvious that human beings are able to perceive visual information in the periphery. But, the number of detected and correctly identified stimuli has been shown to vary with the angle between the stimulus and the fixation point, the visual and/or cognitive load induced in the central field of view and the stimuli characteristics. Generally, in the central (functional) field of view small differences and details in the information can be distinguished and identified with high accuracy, while the main task of the peripheral vision is to detect movements and light changes. In the traffic environment, the demands and complexity of developing situations rather than speed have been reported to determine the extension of the driver's peripheral field of view. According to Miura a reduction of the functional field of view while driving, as a result of attentional focusing, is followed by a corresponding extension of the peripheral field of view. The objective of the study was to investigate drivers' ability to acquire in-car information displayed in the vertical periphery during driving and to determine whether this is achievable without the driver shifting focus from the forward field of view. Based on a literature review, the influence of different codes to convey the information and the complexity of the driving task were also examined. (A)
Abstract