What should I do?--a study about conflicting and ambiguous warning messages.

Warnings are intended to reduce accidents caused by hazards. Behavioral compliance is the most important measure of warning effectiveness. However, in result of diverse circumstances (e.g., distraction, misuse, negligence), conflicting or ambiguous safety messages can be perceived. Since these are recurrent and can result in wrong behaviors encompassing severe consequences, such cases should be studied for safety purposes. We report findings on the participants' compliant behavior when performing a work-related task, while immersed in a virtual environment, and investigate the effect of conflicting messages on compliance with warnings. Two warnings (one regular and one with an appended out-of-order sign) and two types of signs (static and dynamic) were considered. The warning with the out-of-order sign configures the case of potentially conflicting messages. The gender effect was also investigated. The participants' behavior was assessed regarding to pushing a button as directed by the warnings. In the "out-of-order" warning, compliance was higher in the dynamic situation (53.3%) than in the static one (3.3%). Comparing with the non-conflicting warning, compliance was higher for both situations (static: 76.7%; dynamic: 100%). Women complied more than men. Although these results have limitations in their generalization, they are nonetheless relevant and deserve to be studied further.