I think this is an incredibly complicated question. One of the things you learn about psychology if you study enough of it is that people really are all different, and we all deal with things in different ways, so anything is possible. But if you follow a large enough population, you do start to notice certain trends.
I can’t say anything definitive about repressed memories, but I would like to talk a little bit about two important concepts in psychology. The first is the idea of the misinformation effect. This was made famous by a psychologist named Elizabeth Loftus, who showed through a series of experiments that you can literally implant memories in people’s minds by asking them the right kinds of leading questions. For instance, in one experiment, she had study participants watch a video of a car running a yield sign and colliding with another car. When she later questioned study participants about the car running a stop sign, they remembered the car running a stop sign—not a yield sign.
A great deal more work in that field has been done and it has all been hotly contested, so it’s hard to say anything definitive about misinformation and false memories at all. I personally think it’s very compelling research and that it casts a lot of doubt on things like repressed memories.
I thought I had a good term for the other psychological concept I wanted to talk about, but after some research I realize I’m cobbling together a couple different ideas. Basically, our brain has a lot of mechanisms for protecting us from things that are just too painful for us to experience. One of those defense mechanisms is dissociation. Based on what I know about the neurobiology of emotional memory, tt seems to be not a huge stretch to go from dissociating an experience to failing to encode it properly.
So I think this then begs the really interesting question of whether a repressed memory is actually encoded differently in the brain (and if it was encoded improperly, how would you recall it later, anyway?) Scientists have a pretty good idea of how memories are formed, and memories are ostensibly physical networks in your brain. So if repressed memories do actually exist, I think there should probably be something physically different about them, or at least about accessing them. And I don’t think we have enough information to state anything definitive about that, but I also have yet to see any evidence of that in research on repressed memories.
So, in summary: I don’t think they exist. But it doesn’t seem impossible, either, and we don’t really have any way to know for certain.
And most importantly, I hope none of this is pejorative or minimizes the experience of people who have undergone a great trauma and struggled to deal with it.