How to prove amnesia

Question

So basically, a guy (criminal, fraud, con artist and generally very untrustworhy person) is involved in an accident and suffers total memory loss. He remembers absolutely nothing about his previous life. Naturally, he gets captured almost immediately and interrogation ensues. Of course, everybody thinks he is just trying to pull some stunt and do not believe a word he says.

How could this guy possibly prove (or at least convince those people), he really lost his memory?

Notes:

• It is a fictional kind of amnesia, meaning no memories whatsoever up until the accident, no side effects, undetectable by brain scans or similar things, and permanent
• People who captured him are not police, more like some entrepreneurs he ripped off before
• No friends or relatives are available, very little is known about the guy

Answer 1

You aren't going to like my answer. He can't.

Proving that something does exist is possible. Proving that something doesn't exist...that's a harder thing.

The best you can do is provide evidence of absence. Your guy is trying to prove a negative, which, while not impossible, is not completely provable.

In your notes, you have "no friends or relatives" which is bad, because the first thing I thought of was that they could threaten or kill people he formerly loved, and his reaction would tell them that he does not remember them.

This isn't proof, but the best you could do do is set up a situation where him remembering is in his best interest or the best interest of someone he cares about, but he doesn't. Unfortunately, your criminals will already be doing this with torture, and they might just believe that he's difficult to break.

In this case, you don't want to look at what is, but what other characters coming into contact might believe.

If one of them knew him well, they might set up a situation, a test, where they know how he would react if he had all the info that he claims he does not have. This would have to be something more clever than mere torture, and it would not come under the purview of worldbuilding--this would be a plot point, and this site isn't for that.

Answer 2

There are things people forget and things they will always remember. A good psychiatrist will be able to tell the difference between fake and real amnesia, madness etc.

One of the questions will be along the lines of "how many legs does a cow have?" as it's something that you'll never forget but someone feigning amnesia/madness might think they're supposed to have forgotten. However, this is consultant psychiatrist grade examination, whoever picks this guy up off the street is not going to be able to do it.

You're talking about classic fictional amnesia, it doesn't work that way in real life, so you'd need a matching fictional psychiatrist to tell if it was true.

Answer 3

I think you also need to explore the question of "Why bother?" What is the goal of the people who have captured him? Certainly some criminals who have been cheated aren't going to release the guy just because he has amnesia; they'll just kill him anyway. Ask yourself: what difference would it make to their plans if he has real amnesia or is just faking?

Perhaps they think he might know where the money went or somesuch. In that case, they'd likely just treat him like he's pretending amnesia as a way of getting out of torture, and torture him all the harder. Whether the guy resists torture by being tough or by having amnesia doesn't really matter.

I think the others have covered your actual question: bring in psychologists to question the guy, try to trip him up. Shows like Lie to Me and The Mentalist provide good background for how such people might get a faking amnesiac to spill the beans. The motivations of the capturers will be important in picking what experts they might be able/willing to bring in.

Answer 4

So, you give this fictional character a fictional kind of amnesia and want to know how he would go about proving he had it. If he cared, then that would prove he was able to understand his predicament. If he understands his predicament, he clearly hasn't forgotten everything he's learned. The attempt would disprove the claim. I love the inability of people to see the stupendously obvious contradictions in their own thinking.