Tetrad of media effects

The tetrad first appeared in print in articles by McLuhan in the journals Technology and Culture (1975)[2] and et cetera (1977).

[3] It first appeared in book form in his posthumously-published works Laws of Media (1988) [4] and The Global Village (1989).

The laws of the tetrad exist simultaneously, not successively or chronologically, and allow the questioner to explore the "grammar and syntax" of the "language" of media.

McLuhan departs from the media theory of Harold Innis in suggesting that a medium "overheats", or reverses into an opposing form, when taken to its extreme.

[6] Visually, a tetrad can be depicted as four diamonds forming an X, with the name of a medium in the center, where the left/right direction reflects the figure/ground association.