The main characteristic of the expressive function is that it is speaker-reflexive. The speaker wants to articulate his own position so as to clarify his own position it for himself, to justify his actions or to reach a decision. The main projections within the dramatic structure, where the expressive function predominates, are sudden exclamations and soliloquy. The latter has an intrinsic element of reflection and deliberation.
An utterance always has an expressive function in the external communication system even if this function does not dominate the internal communication system. An example of this is Poor Thing. An utterance with a predominantly expressive function does not always change the dramatic situation; in some cases it is just a clarification of the dramatic situation as seen from the viewpoint of a certain figure. In other cases, it is as its name suggests, a display of the emotions of a certain figure. A splendid example of the latter is Macbeth's soliloquy after hearing his wife's suicide(V,v):
To-morrow, and to-morrow, and to-morrow,
Creeps in this petty pace from day to day,
To the last syllable of recorded time;
And all our yesterdays have lighted fools
The way to dusty death. Out, out, brief candle!
Life's but a walking shadow; a poor player,
That struts and frets his hour upon the stage,
And then is heard no more: it is a tale
Told by an idiot, full of sound and fury
Signifying nothing5.5
Here the dramatic situation is not changed but the speaker (Macbeth himself) displays his emotions. However if, in a predominantly expressive speech, a decision is reached the dramatic situation is changed. And example of this is the Epiphany from Sweeney Todd. In this emotive speech, Todd expresses his frustration and anger toward the rest of the world. And during this outburst of emotion, he changes his plans: instead of wanting to kill one man, he now wants to kill all men. A more in-depth analysis can be found in the next chapter.