Change detection and occlusion modes in road-traffic scenarios

Change blindness phenomena are widely known in cognitive science, but their relation to driving is not quite clear. We report a study where subjects viewed colour video stills of natural traffic while eye move-ments were recorded. A change could occur randomly in three different occlusion modes—blinks, blanks and saccades—or during a fixation (as control condition). These changes could be either relevant or ir-relevant with respect to the traffic safety. We used deletions as well as insertions of objects. All occlusion modes were equivalent concerning detection rate and reaction time, deviating from the control condition only. The detection of relevant changes was both more likely and faster than that of irrelevant ones, particularly for relevant insertions, which approached the base line level. Even in this case, it took about 180 ms longer to react to changes when they occurred during a saccade, blink or blank. In a second study, relevant insertions and the blank occlusion were used in a driving simulator environment. We found a surprising effect in the dynamic setting: an advantage in change detection rate and time with blanks compared to the control condition. Change detection was also good during blinks, but not in saccades. Possible explanation of these effects and their practical implications are discussed