This paper describes a set of experiments investigating the interaction between the location of eye fixations and the detection of unexpected motion while driving. Both psychophysical and real-world observations indicate that there are differences between the upper and lower visual fields with respect to driving. We began with psychophysical experiments to test whether the detection of unexpected motion Is inherently different in the upper and lower visual fields. No difference was found. However, when texture was added to the driving surface, a large difference was found, possibly due to optokinetic nystagmus stimulated by the texture. These results were confirmed in a driving simulator, and their implications for head-up displays (HUDs) explored. We found that the same upper/lower field asymmetry could be found with digital HUDs but not with analog HUDs. These experiments illustrate how virtual environment technology can connect knowledge from psychophysical experimentation to more realistic situations.

Two experiments examined the effects of pictorial realism, observer interactivity, and delay of visual feedback on the sense of “presence.” Subjects were presented pairs of virtual environments (a simulated driving task) that differed In one or more ways from each other. After subjects had completed the second member of each pair they reported which of the two had produced the greater amount of presence and indicated the size of this difference by means of a 1-100 scale. As predicted, realism and interactivity increased presence while delay of visual feedback diminished it. According to subjects' verbal responses to a postexperiment Interview, pictorial realism was the least influential of the three variables examined. Further, although some subjects reported an increase in the sense of presence over the course of the experiment, most said that it had remained unchanged or become weaker.