- ELM (Elaboration Likelihood Model) : ELM is the acronym of Elaboration Likelihood Model which is a theory that posits two (2) routes to persuasion, via either conscious or automatic processing. It is a a theory of attitude change that specifies the conditions under which people will think carefully about the content of a persuasive message. It distinguishes between two types of processing - the central route to persuasion and the peripheral route to persuasion