Large public displays are widely used in public spaces for serving information. The flow of the information is largely a one-way passive communication due to a lack of user-content interaction, which in some ways limits its effectiveness as an information display system. We propose a use of mobile phones as a tool to interact with a public display. Our proposed mobile-public display user interaction uses a mobile phone to control and retrieve information from a public display. In this paper we present results of a usability test of our proposed interaction, which indicated that there was a strong correlation between the information retrieval performances and the participant's level of engagement with the mobile phone.
