Signals are Informative but Slow Down Responses when Drivers meet Bicyclists at Road Junctions

Three experiments used a laboratory analogue to the task of driving assess drivers’ responses to encounters with a bicyclist at a T-junction. Specifically, a comparison was made between the bicyclist indicating an upcoming turn with an arm signal, an informal signal of intent, or no signal. Formal arm signals were observed to be successful in informing drivers of the bicyclist's intentions and they were easier to understand than informal signals. Simple failures to react to the bicyclist in time were more common at shorter thinking times, but incorrect positive responses were not affected by thinking time. These experiments showed that arm signals often dampened the participants’ decision-making processes, leading to a lower probability of their stopping in time when the bicyclist was at risk. The same held for informal signals in which there was eye-contact between the bicyclist and the participant. These effects occur because both arm signals and eye-contact are communicative acts, evoking extra stages of involuntary cognitive processing in the drivers, which slows their reactions.


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  • Accession Number: 01013435
  • Record Type: Publication
  • Files: TRIS, ATRI
  • Created Date: Dec 6 2005 7:52PM