As I will discuss in the Section 4, before embarking on more unconventional measures, a central bank is likely not only to fully use its policy rate instrument, but also to exhaust all other options in its existing toolbox in order to preserve price stability.
And, of course, a successful outcome of the more dramatic unconventional actions depends on a sound communication with the public and on the existence of a clear, credible commitment of the central bank with respect to achieving its monetary policy objective (a well-defined definition of price stability in the case of the ECB).