GENERAL INTERACTION EXPERTISE TEST:
USER EXPERTISE AND ITS EFFECTS ON USABILITY TESTING OF CONSUMER PRODUCTS

Since the times of Henry Dreyfuss, collaboration between consumer ergonomics and design research have proved to be fruitful for designing ‘easy to use’ consumer products.  However, together with the diffusion of digital technologies to everyday life and inevitable changes in modes of interaction, practitioners of conventional consumer ergonomics research started to experience problems in embracing the broadening scope of interaction.  In order to cope with the new circumstances, the discipline of Human Computer Interaction (HCI) was referred as a source of appropriate ways of comprehending and studying the interface between users and products.  After this interplay of disciplines, usability evaluation techniques, especially usability testing, was successfully added to the repertoire of design research.  Nevertheless, although HCI-based approaches and techniques acted like a quick remedy for surfacing problems, there were certain assumptions that were invalid for the case of everyday consumer products. 

One of the mismatches that will be dwelled on in this study is how users are perceived and how some of the cruicial differences among users are overlooked within the conventional approaches to interaction, which has serious repercussions for sampling schemes utilized in usability tests of consumer products. 

In this study, a sampling tool (General Interaction Expertise Test) that is developed for accommodating and controlling individual differences in expertise during usability tests will be presented.  In this regard, first the concept of ‘user expertise’ will be revisited by addressing the common misconceptions in the literature about user experience related concepts.  As a second issue, the effects of user expertise on user performance will be discussed in accordance with its influences on validity of usability test results.  Thirdly, the structure of the tool, together with the development process and the rationale behind will be presented.  Finally, the results of the empirical studies done and their implications for design research will be comprehensively discussed.