Playing on users expectations to create a trick device facet or mechanic.
Misdirection is a puzzle mechanic that creates a contradiction between players expectations and the actual rules of the puzzle. This tends to create quirky moments for the player, arousing feelings of pseudo-shame that they "didn't get it.". Misdirection must be limited in use, and obviously resolved, as to not become something bad, like a red herring.
An example I remember from childhood is this, which works best if you read it out loud, or ask it of another person: "Spell 'pots' backwards. What do you do when you come to a green light?"
Now be honest, did you say "stop"? If yes, reread the actual question asked. The first request, to spell "pots" backwards, appears to prime the brain, which then have listens to the question and thinks it knows the answer. Though it's curious, even if asked in isolation, without the pots prompt, some people answer "stop". The question itself can be seen as misdirection as one typically asks about red and yellow lights, not green ones.
A physical example is a book that opens from the binding: opposite how it normally would. For bonus misdirection, a lock can be added to the book, to dissuade a player from inspecting the book more closely, assuming they need a key. An escape room player will kick themselves later for not seeing this, as they're aware that they need to investigate and not be deceived.
Misdirection needs to be subtle and significantly related to the puzzle at hand. Puzzle pieces that lead the user astray, or are superfluous to the puzzle's device, are called red herrings, and they have no place in games.
For example, suppose an escape room player finds a golden key. They will proceed to try that on any lock they find, particularly ones of import. However, if the key is never used, or worse, no locks are ever opened, the key is a red herring. It served no purpose and the player had no ability to know that it served no purpose.
On the other hand, the key might bear symbols which are used to press panels on a locked door. In this case the user would attempt the key, thinking it doesn't work, but if they pay close attention would realise the symbols on the key unlock the door. In this case of misdirection the key is a vital piece of the puzzle, and it's correctly associated with the door.
An attentive person can see through misdirection, but may be unable to identify a red herring.
I would like to create fish themed escape room that has an actual red herring, using other fish as misdirection to finding it. Then I'll send unaware puzzle designers into the room and watch as they try to analyse what's going on.
Misdirection doesn't fundamentally alter the device of a puzzle, therefore it isn't a device facet. This creates a bit of an uneasy feeling about puzzles which are fundamentally only a misdirection puzzle.
Back to the "pots" example from before, the fundamental puzzle question is "What do you do when you come to a green light?" This is a basic trivia device, but the trivia on its own is completely uninteresting. It is some simple that we'd barely consider it a puzzle at all.
But maybe this strengthens the distiction between puzzle aspects, that focusing on any part of a puzzle can lead to interesting results.
If you have any questions, need an example, or want clarification, then let me know. Ask on Discord or Twitter.
Assume everything in this reference is a working draft, there's prone to be some mistakes and inconsistencies. I figure it's best to publish and get feedback rather than write for years in secret. The terms will change, the structure will shift, and the bugs will be chased out. It'll take a while.