Touch interfaces have recently become the de facto interface for various mobile devices, such as smartphone, smartwatch, and tablet devices. Using a touch interface has lots of advantages, such as ease of learning and ease of use. However for various reasons, a touch interface has usability problems and various studies have been conducted to cope with these problems.
In this dissertation, I focus on the possibility of the hover space, a space over/around the touchscreen, as a potential solution to these problems. And I utilize the hover space to propose a new interaction technique that users can conduct it and learn how to use it easily. I review previous studies about the hover space and proceed to find two unexplored usages of a hover space: utilizing the hover space as a quasi-mode for overlapped operations and an extended input space where a user can continue touch gestures. I propose two new interaction techniques for these unexplored usages and show the new techniques can improve the usability of touch interfaces.
I propose a new usage for the hover space that utilizes the hover space as a quasi-mode for maintaining the primary operations while a user conducts secondary operations. As a potential technique, I propose the Push-Push technique. The Push-Push technique is a new drag-like operation that is not in conflict with page transition operations. Thus, page transition operations can be conducted while performing Push-Push.
I propose Transture, which is a design concept that utilizes the hover space as an extended input space for a touch interface. Transture enables users to continue performing multi-touch gestures that are started on the touchscreen but can continue into the air beyond the boundary of the touchscreen without conflicting with traditional touch interfaces.
I design the new interaction techniques that have no conflict with traditional touch interfaces and provide better user experience than traditional touch gestures. I observed users' behavior in the hover space while they used conventional touch interfaces and the observational results were used for minimizing conflicts between the new interaction technique and traditional touch gestures. The findings from the iterative design process of the new techniques show that the hover space can be used for designing a new interaction technique that is easy to use and learn. I discuss three design issues: minimizing conflict with touch interfaces, maximizing consistency to touch gestures, and providing appropriate feedback for finger movements in the hover space, that may have an important role in making proposed techniques have better subjective characteristics.