GC-BC is a special case within the larger category of reward-punishment behavior modification.
The best defense against all forms of it are to be aware of it and how it works (of course; knowledge is power), and to play the game of psychological warfare back at them, playing hard, and playing for keeps:
GENERAL RULES
• If someone wants to be nice to you, do you favors, accept them graciously, always superficially behaving as if there were no strings attached (i.e., don’t do anything at all to reciprocate other than warmly saying “thanks”) unless they make very explicit quid pro quo proposals
• If someone is being hostile towards you and making threats, deal with the threats as if you did not even for a moment comprehend any implicit “unless” tradeoffs; be dense enough to extract very explicit promises / threats.
• Retain (if only in your own head) the clearest possible sense of what you would be doing if there were no rewards and no punishments being offered, other than whatever positives & negatives are intrinsically part of the decision that they appear to be trying to influence
CONTEXT NOTES (THIS IS IMPORTANT!)
• All forms of r&p, including GC/BC, are at their most dangerous when the people making use of it are able to isolate you from any contact other than themselves, without you realizing it. When it is not practical for them to isolate you and surround you exclusively like that, their next best choice (and a common modality) is to isolate you and several others they are similarly trying to control and form a “community” in which they retain the final authority. (They can manipulate you folks against each other, making the community of victims behave as Good Cop, or even as Bad Cop, while Staff take the other role). The more that you can obtain feedback from people genuinely outside of the scenario, the less they can control all sources of interpersonal gratification. Or of criticism, for that matter. Be aware of being cut off, either as an individual or as part of a population.
• R = C/S where R = whatever positive reinforcement you are able to receive from the people in your social context, C = your confidence of being able to cope with and participate in the social context, and S = your self-will, or tendency towards personal stubbornness in determining what you will & won’t do rather than doing what others around you want you to do. With that in mind, accept that as a human being you need C. (That is, over time you need, often enough, to feel that you are a part of the social context and can participate in it and get what you need, socially speaking). Well, the manipulators are deliberately controlling R, or as much of R as they can control, hoping that you will respond by reducing S in order to get some C out of the situation. Being aware of all this won’t make it change, insofar as you remain human. You do not, however, have to get it (a nice hit of C) “right now”, and as long as you can get it from somewhere you don’t need to get it from them. If there is a source of positive reinforcement without hooks embedded in it somewhere in a context you’ll be part of reasonably soon, you learn to hold out for that and, metaphorically speaking, hold your breath in the meantime.
• From the above section, you get a sense of how the passage of time plays a part here. The routines they use kick in and start working well after they’ve had you deprived of other social contexts long enough to feel it. Know it, expect it, watch it happen, and outwait them. It costs them a lot of dedicated persistence to isolate you as an individual. The group-community scenario is designed to work over a much longer period of time, and is more pernicious, but it’s also inherently weaker as the other victims of the scenario can be a source of positive reinforcement and connectedness if you play them and don’t just let the manipulators play you and the other victims. Remember, you, too, are a source of reinforcement and feedback to everyone in the environment, so you, too, need to reward and/or withhold reward and approval and whatnot in keeping with the extent to which the others are supporting what you need to see supported. And, ultimately, the other victims are being mistreated by the manipulators and therefore, by definition, have an axe to grind if you can help them catch them out at it.
• It is theoretically possible that you can get them to realize you understand what they are doing, know how it works, and aren’t going to be played like that, and that they will come out and say, in essence, “OK, we’ll deal with you straight”. But I’ve never seen it and I think you should not expect it. You should certainly not make that your goal. Much more commonly, they will get frustrated and annoyed. With you, certainly (count on it!), but also with each other. If you’re really really good you can play them off against each other despite being in a much more precarious position, if only because they will often be unaccustomed to having the tables flipped on them.