The formation of this belief requires a certain level of threaten and a certain time of exposure to these extreme anxiety and stress. It is in somewhat degree similar to "learned helplessness" since in some cases even when the victims is going out and apparently have the opportunity to call for help, they give up the chance because of the belief.
These 4 conditions are never fulfilled at a short time-span, it is progressed over different stages. Normally four stages of progression took place. (Namnyak, M. 2007) The first stage is fear. This is the direct feeling when being victimized, we may refer it as the "Life change". A sudden loss of freedom definitely makes it the worst terror. The second stage is struggling. It is quite intuitive that we will try to escape under the unsafe condition and environment even there may be life danger. We may classify this as the "pressure" type of stress since it is a fight back under extreme danger. The third stage is giving up (exhaustion). Victims stop trying since they know it is impossible. As mentioned earlier, "learned helplessness" mechanism may take place here. It is like "frustration" type of stress because it contains a trial and failure process. The fourth stage is empathy and help, which is the manifest of the syndrome. The victims show positive feeling towards the captors while show negative feelings toward rescuers. We may classify this as the "conflict" type of stress since that there must be a contradiction in humanity for such situation. But this may also be a truly "learned" or "trained" new personality (after "de-personalization") and there is no conflict.
From the social psychology perspective, we may want to first point out the importance of the isolation. Isolation is quite important for the victims to give up struggling and start the "de-personalization" process, which is giving up some basic right and tight one's emotion and behavior to other people (in this case, it is the captors).