What determines drivers’ speed? A replication of three behavioural adaptation experiments in a single driving simulator study

We conceptually replicated three highly cited experiments on speed adaptation, by measuring drivers’ experienced risk (galvanic skin response; GSR), experienced task difficulty (self-reported task effort; SRTE) and safety margins (time-to-line-crossing; TLC) in a single experiment. The three measures were compared using a nonparametric index that captures the criteria of constancy during self-paced driving and sensitivity during forced-paced driving. In a driving simulator, 24 participants completed two forced-paced and one self-paced run. Each run held four different lane width conditions. Results showed that participants drove faster on wider lanes, thus confirming the expected speed adaptation. None of the three measures offered persuasive evidence for speed adaptation because they failed either the sensitivity criterion (GSR) or the constancy criterion (TLC, SRTE). An additional measure, steering reversal rate, outperformed the other three measures regarding sensitivity and constancy, prompting a further evaluation of the role of control activity in speed adaptation. <b>Practitioner Summary:</b> Results from a driving simulator experiment suggest that it is not experienced risk, experienced effort or safety margins that govern drivers’ choice of speed. Rather, our findings suggest that steering reversal rate has an explanatory role in speed adaptation.

本研究在单一实验中通过测量驾驶员的三项感知指标——主观感知风险（采用皮肤电反应galvanic skin response, GSR进行测量）、任务难度感知（采用自我报告任务努力度self-reported task effort, SRTE进行评估）与安全裕度（采用车道越界时间time-to-line-crossing, TLC进行衡量），从概念上复刻了三项被高引的速度适应（speed adaptation）相关实验。研究采用一种非参数指标（nonparametric index）对上述三项指标开展对比分析，该指标可捕捉自定速度驾驶（self-paced driving）情境下的恒定性准则与强制速度驾驶（forced-paced driving）情境下的敏感性准则。实验在驾驶模拟器中开展，24名受试者完成了2次强制速度驾驶任务与1次自定速度驾驶任务，每项任务均设置4种不同的车道宽度工况。实验结果显示，受试者在更宽阔的车道中行驶速度更快，这验证了预期的速度适应效应。但上述三项指标均未能为速度适应效应提供具有说服力的实验证据：皮肤电反应（GSR）未满足敏感性准则，车道越界时间（TLC）与自我报告任务努力度（SRTE）则未满足恒定性准则。新增的转向反转率指标在敏感性与恒定性两方面均优于前述三项指标，这促使我们进一步评估操控活动在速度适应效应中的作用。【从业者摘要】：驾驶模拟器实验结果表明，驾驶员的车速选择并非由主观感知风险、任务努力感知或安全裕度所决定，转向反转率反而能够对速度适应效应起到解释作用。