Andromidius wrote...
Another thought concerning how hallucinations 'have to be built from things you already know'.
While this is true, and even the stranged most surreal things you can dream are twisted memories and thoughts, Indoctrination isn't natural hallucination. The Reapers can add extra details to construct a more convincing lie.
Though that being said, there's not much in the final sequence in ME3 that isn't taken from earlier in the game, unaltered or altered. But its food for thought, just how much can the Reapers manipulate a hallucination or enthrallment attempt?
Something that ties in with other 'visions': the Geth Consensus experience. Aside from the familiar 'gun' Shep uses;
when viewing the historical data on the Geth uprising/Quarian supression Shepard sees them as current Quarians in their full suits. When Shep questions this Legion makes mention that Shepard has never seen an un-suited Quarian so their mind fills in the blanks with the closest reference which is Quarians in suits.
This ties in with our own sense of perception. When we look at a computer generated image; more often than not we can pick up that it is a generated image because it's perfect. Perfection is an unnatural quality so our mind rejects it and we realise it's an illusion. Nowadays they can add in more raw detail like skin discolourations, blurring, higher quality textures and it becomes much harder to distinguish real from creation.
Leviathans indoctrination used people from Shepard's experience 'to give voice to our words' but their version had Shepard in a dank abyss with the figures walking out of nothing. If Harbinger/AI perfected this technique then they could add to this using more than just surface memories but also utilising the suggestive power to convince people they were somewhere familiar by letting them be the ones who 'fill in the blanks' using their own experiences.
I recall a movie in the 50s about a horrid group of monsters and it terrified the various audiences but you never actually saw the monsters themselves. The closest you saw were silouettes against walls as their victims met their fate. People made their own horrors to fill in the gaps left by the filmmakers of the time. A more recent example that invoked terror in me was the Doctor Who episode 'Blink' which featured the Weeping Angels for the first time. They were aliens in the shape of angels that could move almost as fast as light as long as nobody was watching them and it creeped me out even though you never saw them move. The suggestion of how they moved coupled with the very apt placement of the angel props played off my own fears of the unknown, what they did while unobserved, and I found that I too was trying not to blink as much as the characters.
So the Reaper indoctrination might be perfect because it's imperfect, applying enough suggestion to push a mind into the delusion without giving away when they've crossed a threshhold, letting the mind in question fill in the blanks with past experiences just as Shepard did in that Geth consensus.