Lars Hallnäs

Bio: Lars Hallnäs is an academic researcher from University of Borås. The author has contributed to research in topics: Logic programming & Interaction design. The author has an hindex of 18, co-authored 46 publications receiving 1741 citations. Previous affiliations of Lars Hallnäs include Chalmers University of Technology & Swedish Institute of Computer Science.

Slow Technology – Designing for Reflection

Abstract: As computers are increasingly woven into the fabric of everyday life, interaction design may have to change – from creating only fast and efficient tools to be used during a limited time in specific situations, to creating technology that surrounds us and therefore is a part of our activities for long periods of time. We present slow technology: a design agenda for technology aimed at reflection and moments of mental rest rather than efficiency in performance. The aim of this paper is to develop a design philosophy for slow technology, to discuss general design principles and to revisit some basic issues in interaction design from a more philosophical point of view. We discuss examples of soniture and informative art as instances of slow technology and as examples of how the design principles can be applied in practice.

From use to presence: on the expressions and aesthetics of everyday computational things

Abstract: 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.

Informative art: using amplified artworks as information displays

Abstract: Informative art is computer augmented, or amplified, works of art that not only are aesthetical objects but also information displays, in as much as they dynamically reflect information about their environment. Informative art can be seen as a kind of slow technology, i.e. a technology that promotes moments of concentration and reflection. Our aim is to present the design space of informative art. We do so by discussing its properties and possibilities in relation to work on information visualisation, novel information display strategies, as well as art. A number of examples based on different kinds of mapping relations between information and the properties of the composition of an artwork are described.

A Proof-Theoretic Approach to Logic Programming. I. Clauses as Rules

Abstract: In this paper definite Horn clause programs are investigated within a proof-theoreti c framework; program clauses being considered rules of a formal system. Based on this approach, the soundness and completeness of SLD-resolutio n is established by purely proof-theoretic methods. Extended Horn clauses are defined as rules of higher levels and related to an approach based on implication formulae in the bodies of clauses. In a further extension, which is treated in Part II of this series, program clauses are viewed as clauses in inductive definitions of atoms, justifying an additional inference schema: a reflection principle that roughly corresponds to interpreting the program clauses as introduction rules in the sense of natural deduction. The evaluation procedures for queries with respect to the defined extensions of definite Horn clause programs are shown to be sound and complete. The sequent calculus with the general elimination schema even permits the

A stage-based model of personal informatics systems

Abstract: People strive to obtain self-knowledge. A class of systems called personal informatics is appearing that help people collect and reflect on personal information. However, there is no comprehensive list of problems that users experience using these systems, and no guidance for making these systems more effective. To address this, we conducted surveys and interviews with people who collect and reflect on personal information. We derived a stage-based model of personal informatics systems composed of five stages (preparation, collection, integration, reflection, and action) and identified barriers in each of the stages. These stages have four essential properties: barriers cascade to later stages; they are iterative; they are user-driven and/or system-driven; and they are uni-faceted or multi-faceted. From these properties, we recommend that personal informatics systems should 1) be designed in a holistic manner across the stages; 2) allow iteration between stages; 3) apply an appropriate balance of automated technology and user control within each stage to facilitate the user experience; and 4) explore support for associating multiple facets of people's lives to enrich the value of systems.

Reflective design

Abstract: As computing moves into every aspect of our daily lives, the values and assumptions that underlie our technical practices may unwittingly be propagated throughout our culture. Drawing on existing critical approaches in computing, we argue that reflection on unconscious values embedded in computing and the practices that it supports can and should be a core principle of technology design. Building on a growing body of work in critical computing, reflective design combines analysis of the ways in which technologies reflect and perpetuate unconscious cultural assumptions, with design, building, and evaluation of new computing devices that reflect alternative possibilities. We illustrate this approach through two design case studies.

Heuristic evaluation of ambient displays

Abstract: We present a technique for evaluating the usability and effectiveness of ambient displays. Ambient displays are abstract and aesthetic peripheral displays portraying non-critical information on the periphery of a user's attention. Although many innovative displays have been published, little existing work has focused on their evaluation, in part because evaluation of ambient displays is difficult and costly. We adapted a low-cost evaluation technique, heuristic evaluation, for use with ambient displays. With the help of ambient display designers, we defined a modified set of heuristics. We compared the performance of Nielsen's heuristics and our heuristics on two ambient displays. Evaluators using our heuristics found more, severe problems than evaluators using Nielsen's heuristics. Additionally, when using our heuristics, 3-5 evaluators were able to identify 40--60% of known usability issues. This implies that heuristic evaluation is an effective technique for identifying usability issues with ambient displays.

Slow Technology – Designing for Reflection

Abstract: As computers are increasingly woven into the fabric of everyday life, interaction design may have to change – from creating only fast and efficient tools to be used during a limited time in specific situations, to creating technology that surrounds us and therefore is a part of our activities for long periods of time. We present slow technology: a design agenda for technology aimed at reflection and moments of mental rest rather than efficiency in performance. The aim of this paper is to develop a design philosophy for slow technology, to discuss general design principles and to revisit some basic issues in interaction design from a more philosophical point of view. We discuss examples of soniture and informative art as instances of slow technology and as examples of how the design principles can be applied in practice.

A review of stimuli-responsive polymers for smart textile applications

Abstract: Stimuli-responsive polymers (SRPs) are smart materials which can show noticeable changes in their properties with environmental stimulus variations. Novel functionalities can be delivered to textiles by integrating smart SRPs into them. SRPs inclusive of thermal-responsive polymers, moisture-responsive polymers, thermal-responsive hydrogels, pH-responsive hydrogels, and light-responsive polymers have been applied in textiles to improve or achieve textile smart functionalities. The functionalities include aesthetic appeal, comfort, textile soft display, smart controlled drug release, fantasy design with color changing, wound monitoring, smart wetting properties and protection against extreme variations in environmental conditions. In this review, the applications of SRPs in the textile and clothing sector are elucidated; the associated constraints in fabrication processes for textiles and their potential applications in the near future are discussed.