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To Cut Car Pollution, Ask Drivers to 'Think of Yourself'

Researchers tested different road signs to prevent drivers from idling their engines. “Big Brother” eyes helped, but a simple appeal to the “private self” did even more.

Environment and Behavior

Idling your car unnecessarily pollutes the environment, squanders gas, and offends others’ ears. It’s particularly reprehensible in foul-aired places like London, where cars helped push the city past its yearly pollution quota in just one week last January. Can anything be done to curb this wasteful, boorish behavior?

Some researchers believe so, and their weird solution boils down to a couple of tweaks to road signs: adding “watching eyes” and appealing to the “private self.” Based on principles of behavioral psychology, the researchers believe images of eyeballs and requests for drivers to think about themselves are effective at getting drivers to cut their engines, as described in the latest issue of Environment and Behavior.

Rose Meleady, a psychologist at the University of East Anglia, and other U.K. researchers are the latest to explore the influencing power of eyeballs, something that’s long fascinated the region’s research community. Previous studies have suggested that signs with pictures of “watching eyes” are effective at decreasing littering, increasing charitable donations, and preventing bike theft. The reigning theory is that these images make people feel like they’re under scrutiny (perhaps by Big Brother?), and thus they behave in ways more beneficial to society.

Meleady’s group might well be the first to probe the eyes’ effect on motorists. They chose for their experiment a busy railroad crossing in Canterbury, about 50 miles east of London, where pollution levels at the time barely met the E.U.’s target. Motorists here faced with passing trains wait an average of 2 minutes to cross. Nearby is posted a sign from the city council, stating, “Please switch off your engine when barriers are down to help improve air quality.”

The rail crossing in Canterbury. (Meleady et al./Environment and Behavior)

Few actually follow this directive. So the researchers devised some more unusual signs. One was a textless placard containing just an image of menacing eyes. That didn’t have a positive effect. A second sign paired the eyes with the instruction, “When the barriers are down switch off your engine.” This design, pictured above, did score a slight but measurable difference, raising the percentage of drivers who stopped idling from roughly 20 percent to 30 percent.

But things got really interesting with the third sign, which increased the amount of engine-killing to 50 percent. This version simply read, “Think of yourself: When barriers are down switch off your engine.” What could account for the message’s effectiveness? Again, things get quite theoretical, but the researchers believes it comes down to the words pushing motorists into a state of “private self-focus.”

Here’s the argument in a nutshell: The eyes weren’t having much of an effect because they were making people anxious of being evaluated, a feeling that “disrupts the regulation of behavior.” But by asking them to “Think of yourself,” the signs triggered their sense of internal surveillance. The apprehension of external eyeball-derived judgment was gone, and drivers were free to (as the researchers write) “implicitly ask themselves, ‘Am I doing the right thing?’ and to verify this... check against the available rules or standards in the situation.”

So, there’s that. Obviously much work still needs to be done to figure out when an unending gaze is the best solution. Meleady sums it up: “These findings reinforce the importance of directing attention towards the individual when trying to encourage behavior change, and beyond that, suggest it may sometimes be more effective to encourage self-surveillance rather than using cues suggesting public surveillance.”

About the Author

  • John Metcalfe
    John Metcalfe is CityLab’s Bay Area bureau chief, based in Oakland. His coverage focuses on climate change and the science of cities.