As these examples indicate, traffic signs in the U.K. are often on the road itself, where the driver should be looking. And most right-of-way signs are informational: there are almost no mandatory stops in the U.K. (The dominant motive in the U.S. traffic-control community seems to be distrust, and policies are usually designed to control drivers and reduce their discretion. The British system puts more responsibility on the drivers themselves.)

Speed limits in the U.K. are also simpler and better. They are set by road type, so drivers know what limits to expect on highways, rural roads, and urban roads—usually without any signs to tell them. These limits are relatively high, set assuming optimum driving conditions, in contrast to the U.S. limits, which seem to be set with something in between the best and worst conditions in mind. (Precisely where on this spectrum U.S. limits fall seems to vary from road to road, engendering mistrust of the signs in some drivers.) Nonstandard speed limits in the U.K. are rare, so you tend to take them quite seriously when they appear, and they are posted frequently—so you don’t risk missing them if you’re, say, watching the road ahead of you.

I’ve given several talks on traffic in the U.S. and have always found members of the audience to be highly skeptical that the U.K. traffic system could possibly be safer than the one on this side of the Atlantic. As noted, there seem to be more fender benders over here. But not all minor accidents get reported to the police, in either country, and definitions vary. So let’s look at fatalities: everyone agrees on what death is, and fatalities are always reported.

Detailed statistics show that as of 2003, fatalities per mile traveled were 36 percent greater in the U.S. than they were in the U.K. Traffic deaths per million people show an even greater disparity through 2006, the most recent year for which full statistics are available. If the U.S. death rate were the same as the U.K.’s, roughly 6,000 fewer Americans would die each year—that’s half again as many Americans as have died in Iraq in the past five years.

As experimentalists like to remind us, correlation isn’t causation, and differences in traffic-control policies might not be the only reason for this huge difference in traffic deaths. Perhaps people drive slower in Britain? Well, no; in my experience, they usually drive faster. Are cars themselves safer in Britain? Again, probably not; they tend to be smaller, with fewer safety features. It is true that SUVs are more prevalent in the U.S., and that SUVs are often lethal when they hit smaller cars; this likely accounts for some of the difference in fatality rates. But it’s also true, for instance, that when traditional intersections in the U.S. have been replaced by roundabouts, collisions have typically been reduced by about 40 percent, and fatalities by up to 90 percent. And as the U.K. has refined and simplified its traffic-control system over the past 30 years, total traffic fatalities have fallen by about 50 percent. Over the same period, fatalities in the U.S. have declined by just 20 percent; in the past several years, they haven’t declined at all.

I Didn’t See the Gorilla in Front of Me

Conjurers and magicians have long known how to distract people so they miss a move that should be obvious. But it is only recently that social psychologists have come up with dramatic demonstrations of just how tight the limits on our attention can be. One of the most compelling is a 75-second video, by the psychologists Daniel Simons and Christopher Chabris, that shows six male and female students, in black or white T-shirts, passing basketballs to one another. The observer is asked to count the number of passes.