What they don't know is that we have two separate memory systems—we all do—and that all these problems with memory are just the natural results of things our two memory systems sometimes do to keep us alive and functioning under threat.  We don't choose whether or not our memory systems will react that way to an immediate threat, and it's not tied to how strong or brave or smart we are.  It's a reaction to the way all our natural chemicals sometimes work together under stress and threat.

Just deciding not to remember or think about what happened won't make things better, because the memory system we use when we choose (or don't choose) to remember something isn't the one that sometimes causes problems later.  Our two separate systems deal with:

• Conscious, "narrative" memory—like what we did yesterday, where we grew up, what we learned in school, where we are in the novel we're reading, what people we know look like, how to do our work, how to get home, etc.
• Unconscious, "emotional" memory—vivid sights, sounds, smells, emotions, and physical sensations linked to positive (happy, pleasing) situations or negative situations like the experience of loss, pain, or danger
  

The conscious memory system keeps its memories pretty much out in the open, and we can usually find them when we choose to and ignore them if we want to.  But the unconscious memory system keeps its memories tucked away until our brain systems tell it we need them for survival purposes (to pull us toward things that will bring us pleasure, or warn us about things that will cause us pain).  Then it pulls them out and puts them right in front of us where we can't ignore them—as images, sounds, or smells "in our heads," strong emotions, or sensations in our bodies.

Two common examples from ordinary life:

• You went to a movie yesterday that really affected you in a positive way.  Today you're just going about your life, and something reminds you of someone or something in the movie.  Right away, a powerful image from the movie comes up in your mind, and for a few seconds you feel the same pleasure you felt watching it yesterday
  
• Last week you were in a minor accident with someone else driving.  Now you're a passenger again, and even though it's not the same person driving, your body gets tense every time the traffic gets dicey or the driver gets too close to another car, and you feel anxious or annoyed with the driver.
  

That unconscious, emotional memory system is kind of like the nearsighted guy who isn't wearing his glasses and says "good morning" to a parking meter.  It gets things wrong a lot.  Anything that even vaguely reminds it of its memories of pain and danger can seem like a threat and trigger strong survival reactions.  And it can do all this without even paying any attention to the conscious, narrative memory system that understands what's really going on.

But why do we sometimes forget times of extreme pain and danger—like the women who forget the pain of childbirth, the adults who don't remember bad things that happened to them as kids, or the veterans who can't remember firefights or explosions they were in?  That's because of the way our different brain chemicals work together under stress and threat.  In some cases, our brains may "record" intense unconscious memories of sights, sounds, smells, and feelings, but have trouble recording the conscious memories that would help us piece together what happened.  In both cases, this is the body's best guess at what will protect us and help us survive.

So in the old movies, when Doctor Freud says, "You don't remember it, because you're blocking it out!" he's wrong.  You're not blocking anything out.  Your brain just decided not to record it in conscious memory, because it wanted to protect you.

The good news is that there are some excellent treatment approaches, therapies, and courses of skill-training that can help the conscious and unconscious memory systems pool their information and work together for our well being.