Why Young Children Don't Notice Coming Cars.

Children as young as 6 and 7 years old lack the perceptual skills of even slightly older children to interpret important pedestrian safety cues, such as engine and tire noises, a study in Accident Analysis & Prevention suggests. Those skills may start to reach adult levels after about the age of 10, researchers said. More than 13,000 children, ages 5 to 9, are struck and injured by cars while crossing the street in the U.S. every year, according to the National Center for Injury Prevention and Control, a national traffic-safety-monitoring agency.

Experiments at the University of Idaho compared traffic-detection skills in 35 adults ages 19 to 40 and 50 children ages 6 to 9. Participants listened on headphones to 24 recordings of a car approaching at 5, 12 and 25 miles per hour, from both directions, and pressed a computer key when they detected the vehicle, identified its direction and thought it had arrived at their location. The computer was programmed to calculate distances in relation to key presses.

Adults detected the car significantly earlier than children, though 8- and 9-year-olds heard the car before 6- and 7-year-olds. Adults detected the vehicle traveling at 5 miles per hour at a distance of about 48 feet, compared with 35 feet for younger children and 41 feet for older children. On average, the vehicle was significantly closer to children than adults when it was detected.

The vehicle traveling at 25 mph, when engine and tire noises are loudest, was detected significantly earlier than at other speeds. But researchers noted faster-moving vehicles would close in on a pedestrian more quickly and have greater potential to cause a fatal injury. A vehicle approaching from the left was identified with more accuracy, possibly because Americans are accustomed to vehicles moving on the right side of the road, the study suggests. Older children were better than younger children at determining when a vehicle had arrived at their location.

Caveat: The recordings didn't include distractions that normally confront pedestrians. The study had a grant from Nissan Technical Center North America, which provided the vehicle in the recordings.

Title: Developmental differences in auditory detection and localization of approaching vehicles