Drivers Are More Likely to Brake at Yellow Lights If They’ve Just Seen a Depressing Billboard

After seeing positive or neutral ads before a yellow light, drivers were more likely to run it. But after negative ads, they were more likely to break

Yellow traffic light
Courtesy of Flickr user Beaufort's The Digitel

The light has just turned yellow; what do you do? Floor it, or hit the brakes?

Most drivers think they've mastered the rules of the roads. (After all, doesn't everybody rate their own driving above average?) But in this case, the decision might have more to do with the type of roadside advertisements right before the light than a driver's own judgment.

In a recent study, scientists looked at how billboards along the road affected the decisions drivers made at yellow lights. The idea, they say, is that billboards can create positive and negative emotions in drivers, and those emotions can impact how they drive. What they found was that when drivers saw a positive or neutral ad before the light, they were more likely to speed through a yellow. If they saw a negative ad, they were more likely to brake.

Eric Horowitz at the blog Peer Reviewed by my Neurons explains the logic, and some shortcomings of the study:

[Alberto] Megías believes that negative emotions make people more likely to envision negative outcomes, and that this makes them more cautious. While the study provides some evidence that it might be possible to induce certain behaviors through visual stimuli on the road, there are two things worth mentioning. First, it’s possible that running the red light, and thus avoiding the possibility that somebody rear-ends you, is the safer action. The point being that even if you could theoretically nudge people toward a certain behavior, it’s hard to know which behavior is optimal. Second, it’s probably good to be skeptical of any idea that hinges on drivers paying attention to distractions.

Still, Horowitz suggests that this kind of research might soon impact city planning. Cities might take this kind of finding into consideration when placing their ads: the greater good might mean keeping positive ads away from intersections to avoid accidents.

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