How much memory can a Mesmerized subject draw upon?

Question

It's been established that in this edition, you can't Mesmerize someone into recalling things for you; if you say, "Tell me your mother's maiden name," what you get is "Your mother's maiden name." But it's also clear that you can use what memories you have to accomplish a task; if I say, "Go to the ATM, withdraw $2000 dollars, and bring it to me," that's something that can happen — even though they'd need to remember their ATM code to do it. (This was demonstrated when, in the third episode of the L.A. by Night livestream, Victor Temple is unable to compel the reporter to say what he knew about the car theft, but he was able to command him to go get his notebooks and bring them to the club.)

So, if I Dominate someone to "sing the Star-Spangled Banner," presuming they know the song, do they do so? Or do they struggle to harmonize on the phrase, "The Star Spangled Banner"? In broader terms, what is a good guideline for what the power of Mesmerism can and cannot accomplish in Vampire: the Masquerade 5th Edition?

Answer 1

The introduction paragraph has very little to say on the topic, namely

"Vampires cannot use Dominate to extract information, as the victim becomes a mindless puppet while under its influence" [V5, Corebook, page 255]

The discipline itself also states the following:

The instructions must be carried out immediately to the victim’s best ability, and must not contain any conditional actions (“...if you see Henry, give him the document”), as this would require the victim to exercise cognition. [V5 corebook, page 256]

I would use the latter as guideline. Your victim doesn't lose the knowledge they had when you dominated them, they're just mindless and do no thinking of their own. They knew how to withdraw money, which means they can do it. They know which notebook they own as well. If you annoyed your GM and didn't specify he might decide that your victim brings you all the notebooks he currently owns, though...

But even if they knew how to sing "The Star Spangled Banner" - deciding that you want that song and not these exact words sung is a step too far, I'd say. They aren't cognizant enough to decide one is far more likely than the other.

Even with this much comes down to GM decisions and precise wording. Giving very careful orders will always get you further - your order must solve all decision for the puppet.