Research in inclusive design has shown the importance of prior experience for the usability of interactive products. Prior experience, however, is an ill-defined and inconsistently used construct. A number of different definitions and operationalisations of experience exist, but the differing power of these operationalisations to predict the usability of products for older users has rarely been investigated systematically. This study seeks to fill that gap. It is argued that the construct of experience has at least three components. It is proposed that two of these components, exposure and competence, are directly relevant for the current discussion about prior experience in inclusive design and that they can predict to different degrees the usability of a product for older users. In an empirical study, these facets of expertise are each operationalised on three levels of specificity and their impact on usability is assessed. The results show that measures of competence predict usability variables more strongly than measures of exposure and that levels of medium and high specificity are the best predictors. The application of inclusive design principles to a redesigned version of a ticket vending machine-although not resulting in a difference of overall usability-changed the impact of prior experience on usability measures implying an enhanced inclusiveness of the redesign with regard to prior experience. The implications of these findings for the effectiveness of inclusive design for older users are discussed.

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Designers in inclusive design are challenged to create interactive products that cater for a wide range of prior experiences and cognitive abilities of their users. But suitable design guidance for this task is rare. This paper proposes the theory of primary metaphor and explores its validity as a source of design guidance. Primary metaphor theory describes how basic mental representations of physical sensorimotor experiences are extended to understand abstract domains. As primary metaphors are subconscious mental representations that are highly automated, they should be robustly available to people with differing levels of cognitive ability. Their proposed universality should make them accessible to people with differing levels of prior experience with technology. These predictions were tested for 12 primary metaphors that predict relations between spatial gestures and abstract interactive content. In an empirical study, 65 participants from two age groups (young and old) were asked to produce two-dimensional touch and three-dimensional free-form gestures in response to given abstract keywords and spatial dimensions of movements. The results show that across age groups in 92% of all cases users choose gestures that confirmed the predictions of the theory. Although the two age groups differed in their cognitive abilities and prior experience with technology, overall they did not differ in the amount of metaphor-congruent gestures they made. As predicted, only small or zero correlations of metaphor-congruent gestures with prior experience or cognitive ability could be found. The results provide a promising step toward inclusive design guidelines for gesture interaction with abstract content on mobile multitouch devices.@en

By 2020, one in every two European adults will be over 50 years in age. As old age brings along reductions in sensory, cognitive, and motor abilities, product development methodologies have to adjust. While sensory and motor abilities are relatively straightforward to measure, cognitive abilities are more elusive. The paper discusses how different sources of prior knowledge can inspire inclusive design. Special emphasis is put on knowledge derived from basic sensorimotor experiences. This is proposed to complement previous studies investigating the effects of tool knowledge on inclusiveness. Image schema theory as an account of sensorimotor knowledge is introduced and its universality, robustness, and multimodality are discussed. Current evidence for the usefulness of applying image schemas in user interface design is reviewed and implications for inclusive design research are derived. More specifically, a research program is developed that includes theoretical, empirical, as well as practical studies to promote the ideas developed in this paper.@en