Prompted by Gromit's thread on whether we can choose to feel a certain way, I would like to consider what happens when we choose not to feel. By this I mean, not to replace feeling A with feeling B, but simply to stop feeling A. This could be specific and situational ("I don't like feeling defensive when I receive criticism."), or more general ("I don't like feeling angry, or giddy, or . . .)
This is kinda hard to answer, as I think certain types will be able to 'monitor' their emotional responses, or even change them (via changing perception), whereas others will not or won't even desire to do so. What might be beneficial and 'workable' for some might not be so for others. Anyhow, for myself, I can relate to adjusting perspectives such that, given your example, I can learn not to have an emotional reaction of becoming or feeling defensive in certain situations. So, where, 10 yrs ago, I may have gotten defensive in Scenario A, and experienced that emotion, if the same event happened today, I wouldn't experience that emotion at all. Things like that. So yes, I believe one can adjust ones thinking/perspective such that the emotion isn't triggered; however, this leads into very grey territory, as you then have to ask yourself whether it's even a wise thing to do, a necessary thing, what you would gain/lose from that... do some soul-searching.
Is there a downside to stopping a feeling without replacing it with something else? Is that even possible, or are we always feeling something, even if we do not realize or recognize it? Can we stop too many feelings, such that we end up not feeling much at all? Is there such a thing as an emotional vacuum? If we prevent it from being filled back up with emotions, is it filled by something else?
I cannot speak for others, but in my personal experience when I have tried pushing away emotions, they end up ultimately becoming a more powerful force than had I just accepted them and/or analyzed to figure out what the root of the issue is so as to resolve it. And, depending on the nature of the root issue and how deep it might go or how far it might extend, it may take quite some time to unravel. This took me a number of years to really figure out, but I eventually realized that trying to deny their existence meant I just stayed in that overall state longer than I would have had I just accepted them and either worked through them (if they required active working-through and problem resolution, in terms of external changes), or let them flow through me because by their nature they were short-lived and more of a momentary Mood.
I suspect though that it's possible to train your mind to approach the world in a very emotionless way. Would involve conditioning yourself, I suppose, and hardening yourself. It would be a full-blown thing; to do so I think would involve not allowing yourself to experience even positive emotions, because if you allowed yourself to experience positives, the inevitable absence of the positive would leave a more negative (or neutral) - the contrast itself would be noticeable and the neutral might feel negative in light of the absence of the positive. I would also expect sociopaths to have a similar engrained lack of..emotion.. in the sense most have it. But then, I am not knowledgable at all on that sort of psychology.
My initial thoughts... I'll probably ponder some more and edit a bit.