Head-up displays and similar augmented reality systems make driving more dangerous, not safer, according to a new study by the University of Toronto. That's because the array of information that appears on the windshield can easily distract people behind the wheel, offsetting the benefits they're supposed to offer in the first place.
“Drivers need to divide their attention to deal with this added visual information,” said Department of Psychology professor Ian Spence. “Not only will drivers have to concentrate on what’s happening on the road around them as they’ve always done, they’ll also have to attend to whatever warning pops up on the windshield in front of them.”
With the help of two students, Spence measured the impact of this added visual information through a series of tests. First, participants had to identify the number of randomly arranged spots (between one and nine) displayed on a screen as quickly and accurately as possible when prompted. While the test was still ongoing, a black-outlined square randomly appeared on the screen, and participants had to report whether they saw it or not.
The results? Accuracy was high when the square was absent, meaning that little attention was required to confirm that the square had not appeared. However, when the square appeared along with a small number of spots, it was missed about one in 15 times on average.
Furthermore, when the number of spots increased, participants missed the black square about one in 10 times. This suggests that if attention is increasingly occupied by the primary task, people will have more difficulty attending to the secondary task stimulus.
While augmented reality systems are great for accessing key vehicle data in real time, Spence and his team found that it's not enough to simply see something unexpected; one must identify what is seen and respond adequately.
Making things even more difficult, participants were then asked to identify the appearance of a random distinctive shape – a triangle, square or diamond – among the spots. In cases with larger numbers of spots, the shape was often misidentified or missed altogether and as with the first experiment.
“Observers made both judgements more slowly when the shape appeared among the spots by as much as 200 per cent,” said Spence. “The two visual tasks interfered with each other and impaired both reaction speed and accuracy.