Gj. Hole et L. Tyrrell, THE INFLUENCE OF PERCEPTUAL SET ON THE DETECTION OF MOTORCYCLISTS USING DAYTIME HEADLIGHTS, Ergonomics, 38(7), 1995, pp. 1326-1341
Voluntary daytime headlight use by the majority of motorcyclists might
endanger those not using lights: it has been suggested that drivers m
ight scan for lights rather than for motorcyclists per se. Two experim
ents are described that attempted to investigate this issue in the lab
oratory. Subjects had to decide as rapidly as possible whether or not
a motorcyclist was present in each of a series of slides depicting tra
ffic. Experiment 1 showed that headlight-using motorcyclists were more
quickly detected than unlit motorcyclists, especially when they were
far away. However, repeated exposure to headlight-using motorcyclists
significantly delayed detection of an unlit motorcyclist. Experiment 2
showed that this delayed-detection effect occurred when only 60% of t
he motorcyclists shown were using their headlight. Under laboratory co
nditions, at least, subjects readily appear to develop a 'set' for res
ponding on the basis of headlight-use, even when this is an unreliable
guide to the motorcyclists' presence.