Peter Hall writes about Directing Harold Pinter's Plays.

...These three signs in the text all indicate moments of turbulence and crisis--the Three Dots, the Pause and the Silence. By their use, the unsaid becomes sometimes more terrifying and more eloquent than the said. Pinter actually writes silence, and he appropriates it as a part of his dialogue. The actor who has not decided what is going on in this gap will find that his emotional life is disrupted. The pause is as eloquent as speech and must be truthfully filled with intention if the audience is to understand. Otherwise the actor produces a non sequitur, which is absurd and makes the character ridiculous...