A naturalistic study of the impact of message framing on highway speeding

Speeding is the most common road violation, and is one of the main causes of crashes. To protect road users, authorities use sanctions and preventive measures to prompt drivers to observe speed limits. However, the efficacy of prevention messages varies according to a number of factors, among which risk framing is important. We ran a study to test whether gain is more effective than loss (framing effect). Four anti-speeding messages were presented on variable-message signs, along one side of a busy 8-lane highway in France (speed limit: 130 km/h - 80 mph), during 6 weekends. Within a between subject design, the messages differed in orientation (gain vs. loss vs. no message) and theme (crash vs. fuel consumption). The drivers' speed was recorded on the highway 2 km (1.25 miles) after the sign (6486 recordings of speed). The results showed that speed was lower when a message was displayed than in the control condition, and when the message was gain-framed rather than loss-framed. These effects were stronger on the left lanes (overtaking lanes). Hence, gain framed messages are recommended for prevention campaigns at least when no risk factor is salient.