‘One-to-many’ messages technologically mediated through the mass media, making this a distinctively modern form of communication. As a form of long-distance communication it has particular affordances (see distance communication). In terms of communicative functions, its defenders tend to stress information and education functions, while its detractors dwell on entertainment and persuasion functions. The dramatic difference of scale from interpersonal communication highlights the issue of potential influence, leading initially to fears about mass manipulation which later proved to involve an overestimation of media power (see also Frankfurt school; hypodermic model; manipulative model). From a sociological perspective a key difference is its framing within institutions. To be characterized as mass communication, widespread distribution and access are necessary conditions. Issues of power relations are more significant than in other forms of communication. There is no necessary association with the pejorative concept of a mass audience: although the audience is anonymous and widely dispersed, it is also vastly heterogeneous. While it may be live or recorded, it is primarily asynchronous communication—live two-way communication through a mass medium occurs only in such special cases as radio or television phone-ins (which involve broadcast interpersonal communication). Feedback is thus very limited and indirect: it is basically a one-way process. For Mills in 1956, this was one of the two key sociological characteristics of mass communication: the other was that relatively few people could be mass communicators. However, none of these ‘limitations’ renders audiences passive (see active audience theory; uses and gratifications). Technologically, mass communication is conducted through verbal text, graphics, and/or audiovisual media (e.g. film, television, radio, newspapers, magazines, etc.). The diversity of these means (and the need for very different communicative techniques) limits the usefulness of the term mass communication to a broad umbrella concept. See also mass media.