Persuasive technologies can be categorized by their functional roles. B.J. Fogg (1998) proposes the Functional Triad as a classification of three "basic ways that people view or respond to computing technologies": persuasive technologies can function as either tools, media, and social actors -- or as more than one at once.
As tools, technologies can increase people's ability to perform a target behavior by making it easier or restructuring it (Fogg 2002, ch. 3). For example, an installation wizard can influence task completion -- including completing tasks (such as installation of additional software) not planned by users.
As media, interactive technologies can use both interactivity and narrative to create persuasive experiences that support rehearsing a behavior, empathizing, or exploring causal relationships (Fogg 2002, ch. 4). For example, simulations and games instantiate rules and procedures that express a point of view and can shape behavior and persaude; these use procedural rhetoric (Bogost 2007).
Technologies can also function as social actors (Reeves & Nass 1996, Turkle 1984). This "opens the door for computers to apply [...] social influence" (Fogg 2002, p. 90). Interactive technologies can cue social responses through e.g. their use of language, assumption of established social roles, or physical presence. For example, computers can use embodied conversational agents as part of their interface. Or a helpful or disclosive computer can cause users to mindlessly reciprocate (Fogg 1997b, Moon 2000).
Persuasive technologies can also be categorized by whether they change attitude and behaviors through direct interaction or through a mediating role (Oinas-Kukkonen & Harjumaa 2008): do they persuade through e.g. human-computer interaction (HCI) or computer-mediated communication (CMC)? The examples already mentioned are the former, but there are many of the latter. Communication technologies can persuade or amplify the persuasion of others by transforming the social interaction (Licklider 1968, Bailenson et al. 2004) or restructuring communication processes (Winograd 1986).
Persuasion is as old as humanity itself, and records exist to show that the available technology of the day has been used to assist with persuasion for many thousands of years, and has evolved over the centuries to become more effective. The earliest persuasive technologies were those which facilitated verbal communication. The first major advancement though was the technology which facilitated books, flyers, pamphlets, billboards and other forms of widely reproduced written and later visual communication. Sometimes these have a profound effect on culture - for example the Shanghai lady image in 1930s China. Today there are a plethora of electronic technologies which can be used for persuasive purposes.
The key difference between "persuasion technology" in the modern sense and the persuasion which might have been used by a Roman emperor or a radical cleric supporting the reformation is the degree of reciprocal technical equality. In ordinary conversation unaided by persuasive technology, an individual may be more eloquent and persuasive than another individual, depending on their relative talents and training. But persuasive technology can give one interlocutor a technological edge and this might be the decisive factor. Improving intrusive technology e.g. RFID tags make this a rather more subversive process.
There are recorded incidences of carpenters or stonemasons defeating highly respected scholars in classical rhetorical history. This would be more difficult today. Carpenters and stonemasons generally do not have the same access to persuasive technology as experts do.
What distinguishes a persuasion technology from simple "persuasion" is that the individual being persuaded cannot easily respond by creating an equally effective counter-presentation in real time - a lack of reciprocal equality. The means used to achieve this dominance or advantage can be considered in two classes:
On the broader macro level, some types of persuasion technology (such as mass media) are largely controlled by a select few individuals. Alternative view points are seldom presented. Because media is paid for by advertising, advertisers tend to have an editorial influence too. It becomes quite difficult to establish any equality between those who control the media and their guests, and those who would wish to challenge them. Edward S. Herman has written extensively on this topic, and considers it a major social question. Concern has been expressed that such techniques disempower those who do not have knowledge of them and access to them. This is of particular concern in a democracy.
Interestingly, the computer industry itself provides some examples of rejecting certain technologies simply for their power to persuade. Scott McNealy of Sun Microsystems declared his company a PowerPoint-Free Zone, which was seen as a simple attack on his rival Bill Gates of Microsoft. But Lou Gerstner of IBM went further, and declared that no presentation technology at all would be used in his office, but that proposals would have to be presented on a single overhead slide with a single color of marker. He spoke strongly against the distraction of effort into persuasive presentations, and away from the core elements of business cases and real customer service. He did not, unlike Sun, ban his own salespeople from using these, a tacit acknowledgement that there was indeed power to sway decisions in such methods and technologies, and that he considered it an obligation to stockholders not to be himself swayed by it in his own office.
Particularly disturbing is the adoption of the PowerPoint cognitive style in our schools. Rather than learning to write a report using sentences, children are being taught how to formulate client pitches and infomercials. Elementary school PowerPoint exercises (as seen in teacher guides and in student work posted on the Internet) typically consist of 10 to 20 words and a piece of clip art on each slide in a presentation of three to six slides -a total of perhaps 80 words (15 seconds of silent reading) for a week of work. Students would be better off if the schools simply closed down on those days and everyone went to the Exploratorium or wrote an illustrated essay explaining something."
Other subjects which have some overlap or features in common with persuasive technology include: