They look like sentient safes that run around, attempting to avoid being caught by the player. Razputin can open these with a PSI-Punch. Once opened, memories are revealed of the character whose mind the safe is in. Each Mental World (with one notable exception, the Meat Circus) has two memory vaults, for a total of nineteen in the game.
In each Mental World, one of the two vaults is generally in Raz's path when playing through the story. The second vault is in a less obvious spot. The combination of these memories provides insight into the backstory of each character.
The Psychonauts Vault Viewer app for iOS provides a way of viewing the memories outside of the game along with developer commentary.
- Using Clairvoyance on any Mental Vault will reveal they see Raz as a dog catcher.