Memory is a tricky thing.
Recent studies on how the human mind creates memories helps to explain how two people can give diametrically opposed stories while each believing they are telling the absolute truth. Your spouse may not be intentionally lying. He or she may have formed a bad memory.
A memory is a reconstruction of a past event, an event that a person relives in one's mind. When there is a crisis, i.e. an argument or a domestic violence incident, the participant may form gaps in his or her memory due to the volatile nature of the argument. Research shows that the human mind wants to fill that void with something that makes sense to the individual person. Because each spouse on each side of the equation may have different gaps in their own memories, each spouse's brain may fill in those gaps with recollections of totally different events. Sometimes, each recollection completely contradicts the other.
A person's recall tends to be self-serving.
This may explain why two spouses have entirely different stories regarding the exact same event. Each person's mind has filled their gaps in memory with explanations that tend to be self-serving, and logically congruent with their own pre-existing perceptions of the world. Some people say that the judge listens to the husband and listens to the wife and finds the truth somewhere in the middle. That model of weighing the facts is no longer congruent with what we know about memory. The truth is, the truth may not resemble anyone’s recollection.
Don't forget about forgetting.
Not only do people remember things that may not have occurred, people forget things too. The benefits of forgetting are well documented. If you didn't forget, you'd recall all kinds of things from your life that would drown you in a sea of inefficiency. Emotionally, forgetting about your past can help you focus on your present, or “move on” with your life.
This tendency to forget runs headlong into the fact that at trial, people are sometimes asked to recall emotionally traumatic events with specificity. In such cases, the brain is often trying to both reconstruct a narrative that it had forgotten and fill in the gaps from memories that were never fully formed from the beginning. A person’s testimony can turn into a strange brew of some facts interlaced with natural figments of his or her imagination, with no intent to deceive or defraud. Yet, the testimony is just as unreliable.
Want to combat a faulty memory?
One simple method is to keep a journal. Writing down a few thoughts and events every day not only makes a tangible record, it also requires you to reflect. Elaborating on why your memories were meaningful lays down additional memory traces in your mind, making your memories stronger. Taking photographs and labeling them reinforces memories too.