[1] Jan-Petter Blom and John J. Gumperz coined the linguistic term 'metaphorical code-switching' in the late sixties and early seventies.
They wanted to "clarify the social and linguistic factors involved in the communication process ... by showing that speaker's selection among semantically, grammatically, and phonologically permissible alternates occurring in conversation sequences recorded in natural groups is both patterned and predictable on the basis of certain features of the local social system."
They therefore did a study in Hemnesberget, a diglossic community in Norway, to test their hypothesis that switching was topic related and predictable.
When informants listened to the recordings of their conversations, they not only were appalled that their speech had diverged from their dialect, but they also "promised to refrain from switching during future discussion sessions.
"[2] An example of metaphorical code-switching comes from conversation recorded by Susan Gal in Oberwaert, an Austrian town that is home to many ethnic Hungarians.
[4] Another example comes from testimony to South Africa's Truth and Reconciliation Commission by Muhammad Ferhelst, a man who was imprisoned and tortured during apartheid.
"[7] He said "'proper' usage dictates that only one of the theoretically co-available languages or varieties will be chosen by particular classes of interlocutors on particular kinds of occasions to discuss particular topics.
"[7] Though they did not define specific universal domains, Fishman and Greenfield observed five in a study that they published in 1970 on Puerto Rican communities in New York.