The case of sculpting atmospheres: towards design principles for expressive tangible interaction in control of ambient systems by Philip Ross and David V. Keyson (Personal and Ubiquitous Computing, 11(2), 2007, pp.69-79). The paper addresses an important issue in the field of tangible interactions: the lack of proper design methodologies/principles/knowledge. The authors derived some principles from the literature, which they applied in a case study about a living-room interface:

Consider the context of interaction: An interface that is always present in the home environments should be considered an integral part of home life. (...) the ambient device may become a part of the daily rituals and thus should fit into daily home activities.

Map and relate human expressiveness to physical interaction possibilities: Understand what a person may wish to express via the interface, Devise a model that allows a computational system to describe the human expressiveness, Design physical interaction possibilities that allow a person to express the relevant expressive dimensions, Design a model to interpret the expressive behaviour elicited by the physical device.

Capitalize on the expressiveness of form, materials and movement expression: use of form, materials and movement of physical objects can serve as a strong means to convey expression and offer a rich palette that can be used to elicit expressive actions and create meaning in interaction.

Make actual experience pivotal in the design process: Real-life ‘experiential’ testing is crucial to learn how design decisions may influence the interaction experience of people... A ‘Wizard of Oz’ approach

Consider the subjective nature of expression: each individual may interpret the expressiveness of a system or device differently. Secondly, the physical actions of a person have an individual nature since every individual has a different perceptual-motor system. Even within a particular person differences in expression may occur over time due to factors such as refinement of motor skills, mood changes and motivation. Thus it is important that the expressive interface allows for individual creativity and fluctuations in expression.

The principles they consider aims at providing "guidance" to both design decisions and conception of the design process as well as creating a context for an interaction experience (rather than focusing on technological/ergonomica issues).

It's also interesting to see how they deal with the design of gesturing interactions: they carried out a "gesturing workshop" with designers asked to make gestures corresponding to the living room interactions (expressing activities, warmth or attention). They then translated those gestures into mock-up interaction possibilities that they tested.

Why do I blog this? this sort of design principles are interesting starting points; I use them in discussion with game designers for some private projects. The crux issue in tangible interaction is that there is really a lack of methods (think about designing games for the Wii or the DS), especially when it comes to gestures. This paper is a good step towards what I am looking for but the literature about gesturing interfaces/guidelines is still scarce.