Every linguistic utterance takes place in a communicative context defined by the speaker’s orientation and the latter’s associated function. When the orientation is toward establishing contact, the function is called PHATIC; when toward the content, REFERENTIAL; when toward the code, METALINGUISTIC; when toward the addressee, CONATIVE; when toward the addresser, EMOTIVE; when toward the message, POETIC. In English the conative function is illustrated by sentences utilizing a verb in the imperative mode or where the addressee is addressed directly in the vocative.
The structural relatedness in language of the imperative and the vocative categories can be seen in the recent emergence in English (on both sides of the Atlantic) of an unusual intonational pattern for the vocative as an alternate to the traditional one, namely a pattern involving a dropping of the voice on the word for the person named rather than before it. Thus, instead of saying “Good morning, Mark” with an intonation involving a drop of the voice at the end of “morning,” this new version postpones the drop until after “Mark.” Conation is the only factor that binds the two categories and explains the assimilation of vocative to imperative in this case of linguistic change.