Towards a theory of user judgment of aesthetics and user interface quality

The article introduces a framework for users' design quality judgments based on Adaptive Decision Making theory. The framework describes judgment on quality attributes (usability, content/functionality, aesthetics, customisation and engagement) with dependencies on decision making arising from the user's background, task and context. The framework is tested and refined by three experimental studies. The first two assessed judgment of quality attributes of websites with similar content but radically different designs for aesthetics and engagement. Halo effects were demonstrated whereby attribution of good quality on one attribute positively influenced judgment on another, even in the face of objective evidence to the contrary (e.g., usability errors). Users' judgment was also shown to be susceptible to framing effects of the task and their background. These appear to change the importance order of the quality attributes; hence, quality assessment of a design appears to be very context dependent. The third study assessed the influence of customisation by experiments on mobile services applications, and demonstrated that evaluation of customisation depends on the users' needs and motivation. The results are discussed in the context of the literature on aesthetic judgment, user experience and trade-offs between usability and hedonic/ludic design qualities.