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The coming ubiquity of computational things urges us to consider what it means for something to be present in someone's life, in contrast to being just used for something. "Use" and "presence" represent two perspectives on what a thing is. While "use" refers to a general description of a thing in terms of what it is used for, "presence" refers to existential definitions of a thing based on how we invite and accept it as a part of our lifeworld . Searching for a basis on which these existential definitions are formed, we argue that the expressions of things are central for accepting them as present in our lives. We introduce the notion of an expressional , referring to a thing designed to be the bearer of certain expressions, just as an appliance is designed to be the bearer of a certain functionality. Aesthetics, as a logic of expressions, can provide a proper foundation for design for presence. We discuss the expressiveness of computational things as depending both on time structures and space structures. An aesthetical leitmotif for the design of computational things---a leitmotif that may be used to guide a normative design philosophy, or a design style---is described. Finally, we describe a practical example of what designing a mobile phone as an "expressional" might be like.
Hallnäs et al. (Sat,) studied this question.