Drivers must search dynamic and complex visual environments to perceive relevant environmental elements such as warning signs, pedestrians and other vehicles to select the appropriate driving maneuver. The objective of this research was to examine how an Augmented Reality Head Up Display (AR HUD) for warning signs affects driver Situation Awareness (SA) and attention. Participants viewed videos of real driving scenes with an AR HUDs or no display and were asked to report what elements in the driving scene attracted their attention. At the completion of the first driving video participants were given a warning sign recognition test. Participants then watched a second video and the Situation Awareness Global Assessment Technique (SAGAT), a measure of global SA was administered. Participants eye movements were recorded when watching the videos to investigate how drivers interacting with an AR HUD attend to the environment compared to drivers with no AR HUD. AR HUDs for warning signs are effective in making warning signs more attentionally conspicuous to drivers in both low and high clutter driving environments. The HUD did not lead to increased fixation duration or frequency to warning signs in many situations. However when two driving items were in sight (sign and car) and participants needed to decide where to attend, they experienced attentional tunneling. In complex driving situations participants spent a significantly longer proportion of time looking at warning signs in the HUD. In simple driving situations, AR HUDs appear to make warning signs more salient and conspicuous. However, in complex situations in high clutter driving environments AR HUDs may lead to attentional tunneling
