There’s no question that motorcycles pose a particularly potent hazard on the roadways. Bikers are up to 30 times more likely to experience a deadly accident on the road than drivers of passenger cars, according to US government statistics. And more than half of motorcyclist deaths involve at least one other vehicle.
One of the primary reasons that motorcyclists are so vulnerable to traffic accidents may be their paucity, according to a recently published study.
Psychological scientist Vanessa Beanland of Australian National University and her colleagues found evidence that car-and-truck drivers don’t notice bikes because they encounter relatively few of them on the road.
Beanland and her research team used a driving simulator to test 40 adults on their ability to detect and respond to two types of vehicles: motorcycles and buses.
The researchers varied how frequently these vehicles appeared in the simulated traffic. Half of the subjects were subjected to a high prevalence of motorcycles and a low number of buses, with the other half experiencing the reverse.
Although participants were explicitly instructed to search for both buses and motorcycles, the researchers found that the attention of the observers was biased toward whichever vehicle occurred more frequently during the simulated detection drive. This in turn affected the speed at which drivers were able to detect low-prevalence targets.
In the simulated test in which motorcycles occurred more frequently, the car drivers were able to detect them on average from 51 meters farther away than in the tests where they occurred less often. In effect, at a driving speed of 60 km/h, this allowed the drivers an extra 3 seconds to respond. Similarly, drivers had an extra 4.4 seconds to react to buses in situations where they occurred more frequently.
The results, published earlier this year in the journal Attention, Perception, & Psychophysics, suggest that drivers’ inability to always notice motorcyclists is partially due to the fact that motorcycles occur relatively rarely on our roads, and that drivers are simply not on the look-out for them. This implies that the more motorcyclists we encounter while driving, the more easily other drivers notice them.
Beanland, V. et al. (2014) Safety in numbers: Target prevalence affects the detection of vehicles during simulated driving. Attention, Perception, & Psychophysics. DOI 10.3758/s13414-013-0603-1