  According to the subjective Bayesian interpretation of quantum mechanics
(QBism), the instruments used to measure quantum systems are to be regarded as
an extension of the senses of the agent who is using them, and quantum states
describe the agent's expectations for what they will experience through these
extended senses. How can QBism then account for the fact that (i) instruments
must be calibrated before they can be used to `sense' anything; (ii) some
instruments are more precise than others; (iii) more precise instruments can
lead to discovery of new systems? Furthermore, is the agent `incoherent' if
they prefer to use a less precise instrument? Here we provide answers to these
questions.
