Impact of haptic warning signal reliability in a time-and-safety-critical task

The bulk of current haptics human-factors research focuses on mapping basic human perceptual limits. However, many realistic applications demand a better understanding of how to construct more life-like but often less controllable experiment scenarios. In this paper, we study this problem in the context of advanced automobile interfaces. We employ a throttle pedal with programmable force feedback to indicate potentially undesirable situations in the external environment and to gently but steadily guide the driver away from them. We have found evidence that within this scenario, errors in such a warning signal can have a negative effect on the behavior of the driver within the conditions studied. These experiments required a complex protocol and necessarily permitted a variety of participant tactics. Post-experiment analysis revealed that very subtle variations in participant instruction produced large differences in tactics and consequent experiment outcome.