In this scenario it sounds like Guy A and Girl A have a strong incentive to assist in establishing their unique identities. Thus the test would be simply be to ask them to attend two different events simultaneously and immediately report on what they saw. Such accounts can be verified from their promptness as quite likely being firsthand and then verified against other attendees of the event later to ensure they were real descriptions from an attendee.
However, I suspect this isn’t the answer you are looking for.
Damn Guap, it ain’t the roommate switch, just ask chick B to meet you and chick A for a drink at a public place. If she’s too paranoid to go for that, you do not want to sleep with her. Don’t you have enough crazy in your life already?
Have you been reading the same post the rest of us have? Not only has Guap explained that’s not the kind of answer he’s looking for, but it’s easy to fake. Email from home, then walk to the library or a Starbucks or whatever and fire off another email.
Guap, the new theoretical example is bound to make for a funnier thread, but regardless of perspective, I still think that the core issue can’t be resolved in the parameters you’ve established. There’s nothing you can do via email that couldn’t be faked by one person if they wanted to in this situation. So I think Ed’s given you the most useful advice you’re going to get.
(1) Building off Nick Walter. Paranoid Girl B enlists two friends – Friend 1 and 2. She tells both Boy A and Girl A to be at two different book stores at the same time some day in the next week. Friend 1 and Friend 2 each go to one of the stores, and arrange to be in a specific section (e.g., self-help, romance) at the specific time wearing some noticeable piece of clothing (ex. scarf or hat in summer of some bright color).
That night, both Boy A and Girl A e-mail Girl B and report the color of the piece of clothing worn by Friends 1 and 2.
(2) Will only work if Girl B isn’t tech-sophisticated. Boy A and Girl A both compose fairly lengthy e-mails that would take a while to write. At a specific time, both send their messages to Girl B. Hopefully Girl B will think "Wow, one person couldn’t have typed a second message so fast after sending the first, " rather than realizing all the ways one person could pull this off (e.g., keep a composed second message in Word & simply cut & paste immediately after sending the first, access to a second computer one room over with the second message typed & ready to send).
Have Girl A set up a webcam so that Girl B can tell her to wave and a particular time and thereby verify that in fact a woman is actively involved in this process. That’s probably all she needs to reassure her.
-or-
Set up a Ventrilo server that she can join and talk to both of you at once.
Or she can just meet them both in a public place at the same time. Tell them to both wear red shirts and stand next to each other and to be in the Joe’s Muggs at the local books-a-million.
Girl B sends Girl and Guy A an email with a short idendifying phrase included. Girl A and Guy A then snap a picture of themselves with today’s newspaper with said phrase written across the front in marker. This proves both that there are two individuals and that the photo is not a random snapshot Guy/Girl A pulled off Flickr.
Yes, Girl A could be a patsy recruited by Guy A to appear in the photo, but if Girl B is that paranoid, then it’s not worth the effort of Girl/Guy A.
Well, you don’t get proof if you’re going to stick to just email. It’s a matter of weighted probabilities, very non-scientifically put together, by…
Discount anything that has to do with gauging reactions, styles of writing, etc.
Oh. Well, no, then.
Similarly, if you talk to two allegedly-different people on the phone in succession, you can’t actually be sure they’re not one person who’s really good at different voices.
Philosophically, even if you meet with two people simultaneously, maybe it’s just one person who’s able to alter their appearance and appear in two places at once. Like, whoa, man. Just think about it.
You have to convey a piece of information that only you can decode as being in it’s true state or false.
Let information be “i”. If 0, it’s off (person does not possess information). 1, they do (it’s on). 0f, they do, but pretend not to.
People are letters.
Two situations possible:
A (i1) = B (i1); C (i0)
or
A (i1) = B (i1); C (i0f)
So a couple of approaches:
Providing information that is impossible to NOT give back. So when you query C, they HAVE to provide i1 or i0.
Second, provide additional information that changes the equation thusly:
A (i1)(j1) = B (i1)(j0); C (i0)(j1)
or
A (i1)(j1) = B (i1)(j0f); C (i0f)(j1)
So, this is hard and/or soft solution, depending on how the information changes the previous dataset; either the information i & j is chosen so well you flip back to my first assertion (it becomes impossible to NOT give it back), or the soft solution, you keep providing alternating data sets to B and C until one reads back incorrectly (mixing up data). This could take awhile, but since this system is human and thus not flawless at some point B or C would make a mistake and throw an error back.
