Public interactive displays with gesture-recognizing cameras enable new forms of interactions. However, often such systems do not yet allow passers-by a choice to engage voluntarily or disengage from an interaction. To address this issue, this paper explores how people could use different kinds of gestures or voice commands to explicitly opt-in or opt-out of interactions with public installations. We report the results of a gesture elicitation study with 16 participants, generating gestures within five gesture-types for both a commercial and entertainment scenario. We present a categorization and themes of the 430 proposed gestures, and agreement scores showing higher consensus for torso gestures and for opting-out with face/head. Furthermore, patterns indicate that participants often chose non-verbal representations of opposing pairs such as ‘close and open’ when proposing gestures. Quantitative results showed overall preference for hand and arm gestures, and generally a higher acceptance for gestural interaction in the entertainment setting
