It is generally characterized by intolerance of the expression of emotional experiences, which often leads to extreme displays of emotion. Linehan, borderline personality disorder clinician and researcher, proposed the idea that the development of BPD happens during the developmental years, where the child receives the message that he or she should learn to cope with emotions internally and without support from his or her parents.As a result, the child never learns how to regulate or tolerate her own emotions, and fails to learn how to solve the problems that are inciting these emotions.Praise addresses the action or behavior without addressing the emotion behind it.Praise can also be invalidated, because although a child’s behavior is acknowledged and reinforced, the effort or negative feeling they have is not addressed.
Coupled with a genetic tendency to be over-emotional, an invalidating environment is theorized to be one of the two major causes of BPD.
It can be all the more effective if the invalidator finds allies (see flying monkeys section) in their invalidation.
In the movie "The Wizard of Oz," the wicked witch sent flying monkeys to harass Dorothy.
Since then, the term "flying monkeys" was used to refer to those who are manipulated into carrying out abuse for someone with narcissistic personality disorder (Wikipedia).
In terms of invalidation, a flying monkey would be someone who joins in with the original invalidator.