It's now unlawful to shave or use a mobile phone while driving, but reading billboards is still OK. Or is it?

In a recent article published in , University of Alberta researcher Michelle Chan makes a case for regulating emotional while driving.

Chan and U of A co-author Anthony Singhal devised an experiment using a driving simulator, in which participants drove past 20 in one of three scenarios. The billboards in each scenario contained different types of words:

  • Positive words (such as beach, love, cheer or win)
  • Negative words (such as cancer, stress, ulcer or killer)
  • Neutral words (such as engine, statue, lawn or pencil)

Chan hypothesized that drivers would react to the emotionally charged words. The results showed that all three groups showed some , but the highest levels—and those indicating greater driver risk—occurred with the emotionally charged words.
  • For both positive and negative words, participants slowed down when passing the billboards, showing that processing of the emotional words was taking place.
  • Participants viewing the negative words not only decreased speed when passing the signs, but also tended to drift and veer from their lane.
  • Drivers viewing the positive words sped up after passing the signs.
  • Participants increased speed when passing billboards with a target-sign word (one that tested drivers' response time by having them push a button on the when they saw it).

The results showed that drivers' attention can be compromised from viewing billboards, a finding that could be used to make changes to driver training programs, legislation or road design.

Chan says that encouraging marketers to self-regulate billboard language content may be a better first step than to regulate billboards into distracted-. She points to Australia as an example of a country with developed billboard content laws, but says ultimately the responsibility for safe driving rests with the driver.

For now, she says, it may just be safer to keep eyes forward when passing billboards, regardless of what's on them.

"Any kind of distraction is risky when you're driving. But there would appear to be a larger risk when it comes to emotional stimuli."