How your car’s heads-up display impacts your attention

| July 22, 2015

“Keep your eyes on the road!” Every driver has heard it before. With more and more studies proving that distracted driving is fatal, the admonishment has taken on new meaning in an age of smartphones and other digital distractions. But what, exactly, are the mechanics of a driver’s attention? A study released last month, “The Commingled Division of Visual Attention” by Yuechuan Sun, Sijing Wu and Ian Spence, investigates how one aspect of attention — our visual focus — can be divided when using a heads-up display.

dashboard heads up display

Image from mikepetrucci.

Heads-up displays, or HUDs, project details such as speed and directions directly into the driver’s field of view, which in theory is “saving them from having to look down at an instrument panel or display… to reduce distractions and keep a driver’s eyes on the road,” as ArsTechnica explains. Even if the driver isn’t looking down, her attention can still be compromised.

Divided attention is when, in the case of a driver, attention is devoted to two or more tasks such as talking on the phone while driving or focusing on two different locations that are separated by space. Splitting attention, say the researchers, “almost always exacts a penalty.” Both tasks cannot be accomplished using split attention as well as they can be when completed on their own with full attention. In the researchers’ study, a driver using an augmented heads-up display (HUD), who is also trying to concentrate on the road and traffic, may encounter potentially dangerous difficulties.

While the majority of studies have investigated the mechanics of divided attention when performing one task that requires the subject to receive information from two different locations, such as by looking at a display, then back to the road, this study tackled “commingled division,” a less-studied, and less understood, topic, which essentially means information that may be unrelated but which appears within the same field of vision.

The research team undertook two experiments to investigate the commingling concept. For the first one, subjects were asked to count or estimate the number of black spots that flashed on a screen. The subjects were also required to, at random intervals, take on the second task of spotting a flashing square, which also appeared on the screen within their field of view. For the second experiment, subjects were asked to continue the requirements of the first experiment, plus to identify triangles, squares, and diamond shapes on the screen.

The results? In the first experiment, the subjects were less accurate at guessing the number of spots when more than four spots appeared. Their guesses, however, were not impacted by the square’s appearance or lack thereof. In tests where the square did appear, the subjects’ reaction times increased by nearly a half-second on average. They needed more time both to estimate the number of spots and also to see whether the square had appeared. In the second experiment, there was an even longer reaction time when they were required to identify one of three potential shapes. The reaction time increased particularly when the number of spots increased.

The takeaways? Study participants were warned in advance that there might be a secondary task involved (for example, spotting the square), but, as ArsTechnica explains, a real-world driver “would have less expectation of an alert requiring their attention at the same time as they’re supposed to be concentrating on the road.” The resulting split attention, between the information appearing on a driver’s HUD and the road itself, could lead to, write the researchers, loss of accuracy as well as an increase in reaction time to information coming in externally. Learn more and discover the entire study online.

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Category: Transportation

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