Inattentional blindness and information relevance of variable message signs

It has been suggested that Variable Message Signs (VMS) become less effective at communicating important traffic information when irrelevant information is also displayed on them. The purpose of this study was to examine if practice reading irrelevant information on a VMS influenced compliance with, and memory for a detour message. Thirty-nine participants were randomly assigned to one of three groups who drove a simulated road; one receiving only a detour message on the VMS, one group received irrelevant VMS messages before the detour message, and a third group received the same messages but the detour message was inconsistent with their destination. Of interest were both the participants' compliance with the target detour message, as well as their later recall and recognition of the message. The results suggested that, first and foremost, there was significantly lower compliance with the detour message when it had been preceded by irrelevant messages on the VMS. All of the groups showed reasonably good memory for the detour message. The implications of the present study are that presentation of irrelevant messages, including advertisements and safety slogans, may result in reduced compliance to traffic-relevant messages on VMSs.