Almost 1.2 million people die each year in road traffic accidents, with fatalities for children aged 5-9 years four times greater than for adults (Toroyan and Peden, 2007). These statistics highlight the need for a road traffic environment that caters for human error and vulnerability (Toroyan and Peden, 2007). For a pedestrian standing at the kerb, the most salient feature of an approaching vehicle is the relative rate of dilation of the retinal image (tau; Lee, 1976). In order to reliably estimate velocity and time from tau, it is necessary for the rate of looming to be above the perceptual threshold of the observer. Previous research has suggested that children with Developmental Co-ordination Disorder (DCD) may have deficits in visual processing, including dorsal-stream visual motion (Sigmundsson, Hansen and Talcott, 2003). Looming detection thresholds, in eleven children with DCD aged between 6-11 and eleven typically developing age and gender matched controls, were measured under foveal and extra-foveal viewing conditions, for (a) isotropic expansion and (b) isotropic expansion with additional lateral image translation. Our results show that there are situations in which children with DCD may fail to detect optical expansion when the vehicle is 5 seconds away, once the speed of approach exceeds 13 mph. This suggests a developmental immaturity in looming detection sensitivity that may give rise to potential errors in the road crossing behaviour of these children. This research reinforces recommendations outlined by the World Health Organization (Toroyan and Peden, 2007) to set and enforce upper limits on vehicle speed to 19 mph (30 km/h) on roads with high proportions of child pedestrian activity.
- developmental co-ordination disorder (dcd)