Toronto, June 26 (IANS): In a contradictory finding, researchers say the Augmented-reality head-up displays (AR-HUDs) are a threat to safety.

AR-HUDs present digital images on windshields to alert drivers to everything from possible collisions to smart phone activity and are meant to make driving safer.

However, University of Toronto researchers now claim that AR-HUDs are a threat to safety.

"Drivers need to divide their attention to deal with this added visual information," said department of psychology professor Ian Spence, who examined what happens when two sources of information are present in the same visual field.

"Not only will drivers have to concentrate on what is 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," Spence said.

The researchers designed two tests to measure the impact of this added visual information. Participants first completed a series of computer-based trials in which they reported a number of randomly arranged spots (between one and nine) displayed on a screen as quickly and accurately as possible when prompted.

On some trials, they were presented with a secondary stimulus in the form of a black-outlined square and asked to report whether they saw it or not.

The spots and shape were displayed together and the shape appeared unpredictably in only some of the trials.

Accuracy was high when the square was absent, suggesting 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.

When the number of spots increased, the rate climbed to one in 10 instances, suggesting that if attention is increasingly occupied by the primary task, participants will have more difficulty attending to the secondary task stimulus.

The accuracy of the number of spots reported also diminished as the number of spots increased, suggesting that as a primary task becomes more demanding both tasks compete with and interfere with each other.

In a real-life situation - such as driving a vehicle - even more is demanded of a driver. It is not enough to simply see something unexpected, one must identify what is seen and respond appropriately, researchers said.

"It would be necessary to distinguish, for example, between warnings of a collision and a recommendation to make a turn," said Spence.

"Otherwise competing warnings may be more dangerous than no warning at all," he said.