That Damn Amnesia

Amnesia is a very frequently used plot device in narrative works, especially in genres like romance or mystery or melodrama. It’s a perfect way to achieve either of the following (or all):
(a) Draw out a story that should have wrapped up already
(b) Reuse a character’s ‘naïve’ stage of development some more
© Give the villain time to regroup and continue shenanigans
(d) Redo the first stages of romance / threaten to destroy the already existing romance
(e) Let the macguffin fall into the wrong hands / relay information to the antagonist side that the character would never otherwise reveal (and the author can’t think of another way)

I hate the ‘temporary amnesia’ cop out. It always frustrates the audience (as it’s usually used towards the third act and while several things have already developed in the earlier two acts of a story/plot) by forcing the dynamic of the story to feel as being “back to square one”. It also is not such a tame beast as fiction would have us think- it doesn’t come and go like a cold. It doesn’t return with a bump in the head. It doesn’t always return with more shock or trauma, or triggering memories.
Retrograde amnesia, as is the official term for the type of amnesia popular in fiction, also doesn’t often make a person forget all things that happened months before its cause- it usually causes people to forget specific things recent to the trauma’s onset, or even just the trauma related events, while remembering more and more earlier events. It can also be permanent and has no cure. (i.e., the spontaneous recovery cannot be controlled, it happens on its own, if it happens)

What I’m saying is that often amnesia is portrayed extremely well tailored to the needs of the authors, which makes it feel like a gimmick rather than an actual plot twist, used to manage to do things (especially in TV shows) that otherwise the authors couldn’t write into the script, rather than for the merit of the story and its needs.

That said, of course amnesia can be used well for a story. I just don’t see it often.