Wood et al. 2012, reflective clothing and cyclist conspicuity at night

Closed-road night-driving study (Accident Analysis & Prevention) of how reflective clothing affects when drivers recognise a cyclist. Retroreflective strips placed on the moving joints, the ankles and knees, in what is called a ‘biomotion’ configuration, let drivers recognise the rider far sooner than a reflective vest holding the same amount of reflective material. A plain reflective vest is a weak cue because it reads as a bright blob; it is the motion of the limbs that makes a driver perceive a human being. Cyclists tended to overestimate their own night-time visibility and to undervalue ankle and knee markers, so the intuitive choice (a vest) is not the effective one. The study is on cyclists, not runners, but the biomotion principle transfers directly: put the reflective material where the limbs move.