"Parental alienation" may be simpler to accomplish than you think.
Some recent leading edge research using fMRI (functional Magnetic Resonance Imaging-a scan of the brain at work) to investigate the patterns of brain activation in observers of sporting events yielded confirmation of a long held belief of neuroscientists: watching an emotionally engaging event is indistinguishable, at the brain level, from actually participating in it. Same neurons fire, same brain regions are activated, same physical sensations are registered. Or, to be more concrete, watching your favorite football team on TV activates your brain just as if you were playing the game yourself. An entire class of brain cells, called mirror neurons, has been discovered, and the their apparent function, documented many times, is to "mirror" in the brain what the senses detect in the world. Great for football fans, potentially hazardous for children living with conflict.
It has long been assumed by many family lawyers that when children exhibit behaviors indicating that they are afraid of, or angry toward, a non-custodial parent, and when those lawyers represent a parent who complains that they are the victim of a campaign of sustained "brainwashing" by the custodial parent, it must be true. How else could the little angel have become such a strangely fearful and angry child? Now we know.
Children are way more interested in the interaction of their parents than the most rabid football fan. Their very existence depends on the outcome of the conflict leading up to and through the divorce. It's safe to say that the children's mirror neurons are activated every time they witness anger, bitterness, verbal insults, and especially violence between their parents. When one parent is suddenly absent for long periods of time (between periods of possession for the non-custodial parent, for example) and the remaining parent continues to behave in the same angry, resentful, bitter, and critical fashion toward the absent parent, the child's mirror neurons are working overtime, reproducing in the little brains the sensations and emotions that they see, hear, and feel in their crumbling, unstable divorce world.
With this crucial understanding of the underlying neural processes at work, it's easier to understand why a conscious, intentional campaign to "alienate" the child from the non-custodial parent is NOT necessary to create a fearful or angry "alienated" child. All that's required is opportunities for the child to observe the parent with possession to repeatedly talk about or act out the alienating scenario. The child's mirror neurons will do the rest.
This little piece of science also explains why experts who interview children as part of custody evaluations rarely find a "smoking gun" pattern of intentional, pre-meditated parental brainwashing. Children nearly always deny that either parent is actively programming them to dislike a parent. As this research demonstrates, it is not necessary for a parent to "program" the child--all they need to do is act out their disdain, rage, and accusations in the presence of the child. Mirror neurons in the child will do the rest.
One important difference between children of divorce and football fans: children don't have a favorite team--no matter who "wins" in this game, the kids lose, because they are rooting for both "teams". So if those mirror neurons are firing when cheering for one favorite team, imagine how many more are firing when both of your teams are playing each other! It is this over-activation that has led to the standard instruction to divorcing parents to keep their conflict and the communication AWAY from those little eyes and the mirror neurons they are connected to in those little brains. Those little brains are not only overloaded by this lose-lose scenario they are literally a part of, they are permanently altered by the over-stimulation and trauma.
Parental alienation is not just a social problem; it's an insidious disease with permanent consequences for developing brains.