Downloading software via Web is a major solution for publishers to deliver their software products. In this context, user interfaces for software downloading play a key role. Actually, they have to allow usable interactions as well as support users in taking conscious and coherent decisions about whether to accept to download a software product or not. This paper presents different design alternatives for software download interfaces, i.e. the interface that prompts the user if he wishes to actually complete its download, and evaluates their ability to improve the quality of user interactions while reducing errors in user decisions. More precisely, we compare Authenticode, the leading software download interface for Internet Explorer, to Question-&-Answer, a software download interface previously proposed by the authors Dini, Foglia, Prete, & Zanda (2007). Furthermore, we evaluate the effect of extending both interfaces by means of a reputation system similar to the eBay Feedback Forum. The results of the usability studies show that (i) the pure Question-&-Answer interface is the most effective in minimizing users incoherent behaviors, and (ii) the differences in reputation rankings significantly influence users. Overall results suggest guidelines to design the best interface depending on the context (brand reputation and product features). 
Social and Q&A interfaces for app download