The Conclusion of a Driving Study about Warnings Depends Upon How Response Time is Defined

Response time, a common measure of driving performance, is not defined consistently in the research literature, making it difficult to compare studies. To determine if the definition mattered, an experiment was conducted. Sixteen subjects drove on simulated expressway while following a lead vehicle and responded to forward collision warnings associated with the lead vehicle braking and cut-ins (46 total encounters, 4 potential collisions). Six response time types were defined per SAE J2944 by their start (e.g., vehicle movement, warning onset) and end points (e.g., brake pedal contact). Mean times for the warning/no warning response time combinations explored varied from 1.19 to 8.87 s. For this data set, response times that began with the warning presentation and ended with an intermediate-final response (e.g., accelerator release (option A) and maximum jerk (option B)) identified significant warning/no warning differences (p=0.044) but were insensitive to encounter differences (p=0.952), so that definition is preferred.


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  • Accession Number: 01708838
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 24 2019 5:19PM