I get what you're saying, and I think I have a decent (enough) analogy to illustrate the difference.
The memory gaps you are talking about are sort of like lossy compression. The gist of what happened is there, even if you can't remember every detail. Blacking out is more like having a significant chunk deleted from the middle of the file.
The memory gaps you are talking about are sort of like lossy compression. The gist of what happened is there, even if you can't remember every detail. Blacking out is more like having a significant chunk deleted from the middle of the file.