If you're talking about contemplation of citta, as in the Satipatthana sutta
then a common interpretation of that section of sutta is that it's about "mood" or "general emotion", and sometimes is translated "mind state", or "state of mind":
"And how does a monk remain focused on the mind in & of itself? There is the case where a monk, when the mind has passion, discerns that the mind has passion. ... without passion ... aversion ... without aversion ... delusion ... without delusion ... constricted ... scattered ... enlarged ... surpassed ... unsurpassed ... concentrated ... not concentrated ... released ... not released ...
One of the difficulties with this aspect of satipatthana is that the "mind state" tends to be relatively stable. Just as the climate can be relatively stable, even though the weather changes from day to day, the mind state tends (at least for most people) to be relatively stable (scattered for a while, unscattered for a while, etc...). With a little work I can see body sensations, feelings, thoughts, etc. come and go with great rapidity, so their impermanent and not-self characteristics are somewhat obvious. However, as concentration builds the mind state can actually seem more
stable (unscattered!), and it may well be the last thing that one takes as a "true self". ("This is mine, this is my self: this perfect, calm, super-meditator mind...").