Research suggests that human emotion has an impact on cognition. If you’re in an emotional state – happy, angry, sad – that can influence how you perform complex tasks, how long it takes you to search for something or to react to a stimulus.
Consider the task of driving, which demands all of the above (multi-tasking, close attention, quick reactions). As it turns out, driving can be susceptible to "emotional distraction" too, and from a seemingly insignificant source: roadside billboards hawking sunny beach vacations or warning of lung cancer.
Researchers at the University of Alberta recently found that such signage can impact your driving, and not just because it’s visually distracting. The emotional content of a sign matters, too. In a driving simulation study with University of Alberta students, researchers Michelle Chan and Anthony Singhal found that drivers passing signs with negative words (abuse, stress, prison, war) tended afterward to slow down and drift from their lane. Drivers passing signs with positive words (cash, fame, sex, win) did the opposite, speeding up on the simulated road. As the researchers write in the journal Accident Analysis and Prevention:
Our results demonstrate that emotional distraction can impact driving performance by reorienting attention away from the primary driving task to the emotional content and negatively influence the decision-making process. One implication of our findings is that roadway safety could be improved with a careful consideration for where on the road certain billboard types are placed.
Graphic signs for anti-smoking campaigns, or really bawdy billboards for the Las Vegas Strip, probably shouldn’t be placed at the blind bend in a roadway.
Past studies have suggested that negative stimuli holds our attention for longer, causing slower response times in other tasks. On the other hand, the authors write:
Other related research has shown that positive emotions are associated with better and faster physical performance, including jumping higher or running faster, compared to negative and neutral emotions... It is possible that this same type of faster behavior may also be present in driving, and may be due to similar mechanisms connecting positive emotion to human performance.
We'll also throw out one other unscientific theory: Maybe some of those positively stimulated drivers are just really eager to get to the Stardust slot machines.