Materials, use and contaminated interaction Weston L. Baxter 1 , Marco Aurisicchio, and Peter R.N. Childs Design Engineering Department, Imperial College London, Exhibition Road, SW7 2AZ, London, United Kingdom Abstract Materials help communicate meaning to users. This meaning changes with time as the object transforms due to use. Through a two-phase study, this research develops new understanding of how people appraise used objects and the mechanisms driving contamination—the aversion that one has towards engaging with used objects. In the first phase, observations of indicators of use were collected from participants in order to develop a general typology for indicators of use and deduce the sensorial properties of used objects. In the second phase, these observations were analysed to isolate the data, which caused feelings of aversion. The subset of observations marked with aversion was labelled as contaminated. Further analysis revealed three mechanisms driving contamination—hygiene, utility, and territory—presented together as the HUT contamination model. Sensorial properties from the first study were mapped to contamination mechanisms and properties most frequently contributing to contamination were identified. The properties contributing to the various contamination mechanisms differ significantly. Hygienic contamination typically results from transient object states, utility contamination from permanent changes to object characteristics, and territorial contamination from object settings and contextual factors. As expected, the majority of the indicators contributing to contamination are related to material properties. This work acts as a link between material selection and contaminated interaction with used objects. Keywords Interaction; Contamination; Used objects; Sensorial Properties 1 Introduction Materials have a critical role in user experience. When interacting with objects, materials stimulate users’ senses and contribute to the meaning-making process together with other factors such as shape and context. An example of the importance of the sensory stimuli produced by materials is shown by Schifferstein [1] who looked at how containers made of different materials (e.g. glass, metal, and ceramic) impact the resulting experience of drinking. In many cases, the drinking experience was greatly affected by the cup material and other sensory perceptions of the cup. To understand how users experience materials and derive meaning, research is aiming to characterise their sensorial properties. Currently there is a growing interest in this area and research effort has been directed at supporting the understanding and selection of materials for the creation of specific meaning in new goods [2]–[8]. 1 Corresponding author. Tel.: +44 7913361017; E-mail address: w.baxter13@imperial.ac.uk