The motorists' perception of the bicyclists' hand signals

The efficacy of both formal hand signals and informal body signals made by bicyclists was measured on 97 subjects ranging in age from 18 to 75 yrs. Slides of a bicycle rider approaching an intersection were shown to subjects whose task was to respond with the intended action of the rider (Left Turn, Straight Ahead, Right Turn or Stop) and to rate their confidence in their response (high or low). Forty-eight slides were shown comprising eight different signal conditions combined with six positions across the width of the roadway. Subjects were able to derive considerable information from rider position and from informal body signals such as looking over the shoulder. Hand signals were not perfectly recognized with about 20% errors for straight-arm signals and 35% errors for bent-arm signals. The implications for changes in the law and in training schemes are given.