International Journal of Technology and Human Interaction, 11(1), 33-54, January-March 2015 33 Copyright © 2015, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. ABSTRACT Websites usually offer the same rating scale for all users and all tasks, but users can have very different prefer- ences. In this paper, the authors study rating scales from the point of view of preferential choices, investigating i) if user preferences for rating scales depend on the object to evaluate, and ii) if user preferences change after they have rated an object repeatedly, gaining a high level of experience with the evaluated object. The authors frst defned a model of rating scales, identifying generic classes based on features like granularity and visual metaphor. Then, the authors had users choose between three scales, one for each class, for rating two objects with opposite features, frst in a condition where users had a low level of experience, and then in a condition where their level of experience was high. Results showed that user choices depend on the evaluated objects, while their level of experience infuences their overall preferences, but not their choices when they have to rate a specifc object. The authors conclude with some insights and guidelines for designers of interactive systems. A Study on User Preferential Choices about Rating Scales Federica Cena, University of Torino, Torino, Italy Fabiana Vernero, University of Torino, Torino, Italy Keywords: Interactive Systems, Rating Scales, User Choices, User Interface, User Studies 1. INTRODUCTION Rating scales are visual widgets that are char- acterized by specific features (e.g. granularity, numbering, presence of a neutral position, etc.) which allow users to provide quantitative input to a system. Each system uses its own differ- ent rating scale, with different features such as granularity and visual presentation. Examples of rating scales are stars in Amazon (Amazon), Anobii (Anobi) and Barnes & Noble (Barnes & Noble), thumbs in Facebook (Facebook) and YouTube (Youtube), circles in Tripadvisor (Tri- padvisor), squares in LateRooms (LateRooms), bare numbers in Criticker (Criticker). In recom- mender systems (Adomavicius and Tuzhilin, 2005), users rate items to receive personalized suggestions about other items (similar to the previous ones or liked by similar users). Understanding how users perceive rating scales, and why they might prefer one to an- other, is very important for interface designers in order to create more effective and pleasant web sites. This problem can be framed in terms of preferential choices (Jameson, 2012), i.e., when two or more options are available, none of which can be defined as “incorrect”, but one of which can be preferred for some reason (e.g., tasks, user skills, usage context, habits, etc. (Jameson et al., 2011)). Rating scales are widely studied in the literature, especially in survey design (Garland, 1991; Colman et al., 1997; Amoo & Friedman, 2001; Dawes, 2008) and Human-Computer DOI: 10.4018/ijthi.2015010103