George Mason University

News at Mason

A Pulse in Time: Researcher Tests Effectiveness of Auto Warnings

March 12, 2012

By Tara Laskowski and Michele McDonald


Carryl Baldwin, associate professor of psychology. Creative Services photo

Instead of a grating voice telling drivers to turn right or left, or that they’re about to run off the road, motorists could feel a pulse in the car seat.

“We don’t like those voices nagging us,” says Carryl Baldwin, Mason associate professor of psychology. “We don’t like an automated voice interrupting our conversation.”

Baldwin is studying just how safe, effective and even how irritating warnings can be.  She’s using a special driving simulator in Mason’s Arch Lab.

This technology is part of a trend that’s making cars better able to handle different driving conditions, increase safety and reduce ecological waste. These signals also have potential applications in the military and sports.

Other researchers, road safety experts and auto manufacturers could put Baldwin’s study into effect as this technology becomes standard on the road. Safety warning systems could provide a path to a future of autonomous vehicles that drive themselves. But that’s a ways off, Baldwin notes.

“We can’t stop technology, even if we wanted to, so we have to establish effective guidelines to make it as safe as possible,” she says. Guidelines are due out next year.

Car manufacturers are working on these very technologies right now. Last year, Google did an experiment with self-driving cars in California. These cars drove more than 140,000 miles on the highways with only one accident — when another vehicle rear-ended one of the self-driving cars.

With more manufacturers adding these bells and whistles to their cars to warn drivers when they get too close to a vehicle on the road or when they may hit a parked car while trying to back into a parking space, Baldwin looks at the way the alarm systems work and how different they are from vehicle to vehicle.

“The goal is to find a way to match the urgency of the signal with the urgency of the situation it is designed to represent, without either startling or annoying people,” says Baldwin.


The driving simulator in Mason's Arch Lab allows researchers to test different alert stimuli. Photo courtesy of Arch Lab

One area of Baldwin’s research — funded by the National Highway Traffic Safety Administration, among other organizations — focuses on auditory safety warnings that already are available in some cars. She and her team in the Arch Lab study the design and use of auditory in-vehicle displays such as collision avoidance warnings and GPS-based navigational messaging.

In order to examine this issue, Baldwin and her students compare people’s perceptions to auditory, visual and vibro-tactile signals. They have people rate different frequencies of sound and pulse patterns and see how they compare to various visual signals (e.g., color, flashes of light) on things like sense of urgency, annoyance and acceptability.

In other words, they try to find out if this sound is as attention-grabbing or annoying as a flashing light or vibration. They have developed a prototype of a designer’s toolkit to help other researchers working in this field compare stimuli in and across the visual, auditory and tactile modalities.

What Baldwin has found is that in some situations people may prefer a vibration instead of a sound to indicate an alert.  But sounds still tend to get people’s attention focused in the right direction faster than visual or tactile signals.  So, sound may be the preferred modality for time-critical situations such as an imminent crash.

But, when the situation is not so urgent, “Rather than an annoying voice … a vibro-tactile pulse in the seat pan may be the preferred way to tell you to go left or right. It’s noticeable only to the driver, so everyone in the car doesn’t have to hear,” Baldwin says.

“Virtual rumble strips” already can be found in some trucks and cars. They send pulses through the car’s seat when a driver starts to drift into another lane.  “It wakes you up,” Baldwin says.

The technology can go beyond applications in automobiles. Baldwin envisions the military using the warning technology in a belt or sensor built into a soldier’s uniform. Soldiers making their way stealthily through a dark city could receive pulses to tell them to stop or which direction to go, she says.

Baseball coaches, famed for employing elaborate hand signals to give instructions to players on the field, could send information through pulses to their players, who would have the technology built into their uniform or in a belt. “Opposing teams couldn’t see the signals,” she points out.