Crash Warning Interface Metrics Task 3 Report: Empirical Studies of Effects of DVI Variability

This report documents the methods and findings of Task 3 under the project “Crash Warning Interface Metrics (CWIM).” The CWIM project has the objective of examining the potential advantages and concerns of Advanced Crash Warning Systems (ACWS), with a particular focus on the driver-vehicle interface (DVI). Task 3 involved new empirical research to address issues of DVI variability for ACWS systems across vehicles. Two experiments were performed. Experiment 1 addressed whether driver response to a forward collision warning (FCW) acoustic alert suffered when the participant switched from a vehicle with one acoustic alert to a different vehicle with a different acoustic alert. After the alert was switched, participants displayed substantially delayed brake reaction times, particularly in one direction of shift. This comparison provides some evidence of a potential negative transfer effect. Experiment 2 investigated whether people who are unfamiliar with ACWS features were able to identify and comprehend status displays for a variety of existing ACWS. Overall, individuals were not particularly accurate in assessing whether an advanced crash warning system was present (more than 40% of these responses were incorrect), but participants were nonetheless confident in their responses. A degree of familiarity with an ACWS (from reading owner’s manual materials) improved comprehension slightly, but there was no finding of a systematic trend toward either positive or negative transfer. The final section of the report discusses methodological assessments and implications for each experiment.