Abstract. Multi-touch tabletops provide new means for co-located people to work together on a task by directly manipulating objects and tools on a single display in unison. Despite their benefits they also entail new challenges. One major concern is how to help users avoid conflicting actions. Previous work discusses if social protocols are sufficient to regulate coordination, and if policies are needed to enforce specific behaviours. Our study on different variants of a tabletop game shows that providing visual cues on ownership can help to follow social protocols and therefore reduce the need for policies.

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