Abstract
In today's competitive market, User Experience (UX) has emerged as a critical determinant of product success. Beyond usability, UX encompasses the emotional and cognitive aspects of user interactions, shaping perceptions, preferences, and behaviors. However, effectively evaluating UX remains a challenge, particularly in the context of tangible products and complex interactions, such as those found in engineering and industrial design. At the same time, the development of advanced technologies has transformed how designers design and how people interact with products. These advancements have not favored the communication of design intentions during the design process, making it challenging for designers to effectively convey their product ideas to potential users. As the concept of UX gains traction in the design field and its assessment results crucial, literature contributions have so far failed to operationalize UX and make it an asset during design processes. UX multifaceted and complex nature contributes to complicate its effective implementation in practice. The lack of clear definitions and standardized evaluation methodologies for UX has been the first tackled literature gap and primary concern faced in this thesis. By the way, this gap is particularly evident for tangible products without digital interfaces, where traditional evaluation methods may not fully capture the nuances of user experiences. As a consequence, the aim to operationalize UX knowledge particularly applies to product design in this doctoral. An additional concern is the fact that, during prototyping and development phases, designs of ideas are attributed different forms and those can prompt different experiences. In this framework, the overall objective was to develop and employ methodologies for evaluating UX according to multiple dimensions, namely affective, cognitive, and functional (ergonomic). These different perspectives were the results of a state-of-the-art analysis and were deemed to ensure comprehensiveness in UX assessment, as well as favor the development of a holistic concept of UX in product design. In line with the multifaceted aspects of UX, the methods used consider the effects of different degrees of completeness and specification of the represented product, the role of context, different sources of data needed for characterizing UX. More specifically, parallel experiments were conducted using various product representations, including traditional representations and advanced prototyping tools such as Virtual Reality. Initially, the aim was primarily to test the effectiveness of a mixed data acquisition approach combining both subjective (participants’ evaluations) and objective data (through biometric tools). These experiments focused on a limited number of products (a wooden tiny house and iconic candy gummies) but allowed the candidate to identify relevant factors influencing product evaluation and discard others. These findings were then used to design a more complex experiment to explore the simultaneous interaction of various factors and investigate others, which were not tested beforehand. The early experiments provided evidence of the relevance of different forms of product representation. Conversely, it was found that context-clarifying supplementary product information had a negligible effect on product evaluations. This prompted the candidate to investigate other types of contexts, including functional and graphic/functional cues. The importance of familiarity was also introduced as a distinctive element of user experiences. The forms of representation and contextual cues (connected products, representation backgrounds) have all proved their impact in human evaluation of products, despite this takes places unevenly across the three UX dimension. The considerable role of familiarity urges designers to carefully consider appropriate representation and communication forms when new and creative products are being developed. These findings have originally contributed to the understanding of the crucial factors for assessing UX in industrial and engineering design. This research serves as the first step towards developing a repeatable method to evaluate UX holistically industrial and engineering design.