This would in general imply that the central bank should embark on an aggressive policy action in response to expectations instability. And, this will add to the degree of activism displayed by the policy rate.
I will argue that, whilst the central bank must always be ready to take aggressive action if needed, a well-designed institutional framework, which undisputedly assigns the central bank the primary objective of price stability, and the adoption of a clear monetary policy strategy, which quantitatively defines price stability and does not pretend to fine-tune directly the business cycle, can make the latter type of policy activism unnecessary in many circumstances.