The Effects of Statistical Format and Population Specificity on Adolescent Perceptions of Cell Phone Use While Driving

Research on risk communication has established that people are influenced by numerical values as well as geographical reference points, or populations, in statistical messages. The ratio bias theory predicts that messages featuring higher casualty numbers will be more influential than similar messages featuring smaller values. However, research on the effects of population specificity predicts that risk messages containing specific populations with naturally lower casualty values will be more effective than similar messages containing larger populations and proportionally greater numbers. This study investigated the contradiction between ratio bias and the effects of population specificity. Students in a drivers’ education class (N = 112) were randomly assigned to read one of four sets of statistical messages about cell phone use while driving that featured either a general (for example, United States) or specific population (for example, Nassau County), and was expressed using one of two statistical formats, frequencies (for example, “9,000 car accidents…”) or probabilities (for example, “25 % of car accidents…”). Participants then rated their intentions to and perceived risk of using cell phones while driving. Participants who viewed messages featuring general populations along with their naturally larger statistics reported lower intentions to use cell phones while driving than those who were exposed to messages with smaller numbers, but more specific populations. Results suggest that emphasizing larger-valued numbers may be a more effective means of risk communication than depicting specific conditions. These findings have implications for the enhancement of driver safety education to discourage the use of cell phones while driving by teenage drivers.