That's a great point about human conceptual failsafes, but also, the failsafe I would be referring to in your optical illusion example would be the fact that you actually know what you perceive is incorrect, receiving that information from another data source - someone told you what you are seeing is incorrect. There is never a 100% foolproof failsafe, humans can still easily be manipulated and exploited, but manipulation doesn't work 100% across the board for humans either. Is there value in leveraging failsafes across a network? (I'm just throwing ideas out here)