Persuasive technology is the general class of technology that has the explicit purpose of changing human attitudes and behaviours. Persuasive technologies apply principles of social psychology in influencing people; principles of credibility, trust, reciprocity, authority and the like. Social psychologists have spent a great deal of effort over many years in trying to understand how attitude and behaviour change comes about, focusing on the effectiveness of human persuaders, and the persuasive power of messages delivered through non-interactive mass-media, such as newspapers or television. Harnessing the persuasive power of current interactive media, persuasive technology was recently identified as a separate research field, as evidenced by B.J. 1 Fogg’s first discussion of the domain. Fogg characterises computers designed to 2 persuade as the 5th major wave in computing . The scope of technologies that hold persuasive potential is broader than ICT alone, and includes persuasive product design and architectural design, yet the interactive nature of computers uniquely enables user-sensitive and user-adaptive responding, allowing persuasive messages to be tailored to the specific user in question, presented at the right place and at the right time, thereby heightening their likely persuasive impact.