The number of deadly car accidents increases substantially a few days after a terrorist attack, according to a new study published online this week in the Proceedings of the National Academy of Sciences. The findings bolster researchers' long-standing belief that terrorism has effects on behavior and health that reach far beyond the site of the attack.
Surveys conducted after terrorist attacks have consistently found increases in posttraumatic stress and anxiety, particularly among those closest to the violence. But there has been little direct, observational evidence of how terrorism affects the population at large.
To measure an immediate social consequence of terror attacks, demographers Guy Stecklov of Hebrew University in Jerusalem, Israel, and Joshua Goldstein of Princeton University in New Jersey analyzed traffic accidents in Israel during an 18-month period in 2001 and 2002. Controlling for factors such as fluctuations in traffic volume and day-of-the-week patterns in accidents and terrorist attacks, they found a 6% drop in minor accidents 1 day after terrorist attacks and an 18% drop after attacks in which 10 or more people were killed. The authors speculate that the pattern may reflect more cautious driving or more reluctance to report minor accidents in the midst of a larger tragedy. In any case, the short-lived decrease in minor accidents was soon followed by a rise in fatal accidents. Three days after terrorist attacks, traffic fatalities increased by 35% above the normal rate. After larger attacks, traffic deaths surged 69%. Fatality rates returned to normal by the next day.
The authors suggest that some fatal accidents may be disguised suicides. Other accidents may reflect a resurgence in aggressive driving that was at first suppressed in the spirit of social solidarity. The most likely explanation for the increase in fatal accidents, Goldstein believes, is that people return to their normal routines while they are still distracted or upset. He argues that research on other societal consequences of terrorism, such as domestic violence and cigarette consumption, should help clarify whether increased stress is at the root of the traffic fatalities.
"These are very useful, very rare findings," says Arie Kruglanski, a social psychologist at the University of Maryland, College Park. "We know that anxiety and depression go up after terrorist attacks." The new study, he says, is a clever demonstration that terrorism causes cultural trauma "even among so-called normal people who seem to be coping with it and handling it well."