Created by Michael Burgoon, a retired professor of medicine from the University of Arizona, and Gerald R. Miller, the inspiration for LET was sparked by Brooks' work on expectations of language in 1970.
Burgoon, Jones and Stewart furthered the discussion with the idea of linguistic strategies and message intensity in an essay published in 1975.
The theory views language expectancies as enduring patterns of anticipated communication behavior which are grounded in a society's psychological and cultural norms.
Such societal forces influence language and enable the identification of non-normative use; violations of linguistic, syntactic and semantic expectations will either facilitate or inhibit an audience's receptivity to persuasion.
[3] Communication expectancies are said to derive from three factors: Violating social norms can have a positive or negative effect on persuasion.
Usually people use language to conform to social norms; but a person's intentional or accidental deviation from expected behavior can have either a positive or negative reaction.
[3] Positive violations occur (b) when negatively evaluated sources conform more closely than expected to cultural values or situational norms.
Theorists argue further that females and speakers perceived as having low credibility have less freedom in selecting message strategies and that the use of aggressive language negatively violates expectations.