Mind Hacking is an esper ability that is used by the main antagonist, and secretly the actual player character, of Zero Escape: Zero Time Dilemma, Delta. The ability allows him to read the minds of others, and to take over a person for a brief moment to control their actions. Throughout the game, Delta, and by extension the player, had been using this ability to take control of the characters when they made momentary decisions. When someone is mind hacked to make a decision, the thought of it is not retained, and to the person the feeling of not knowing why they made the decision seems as if their psyche is rebelling against the decision they made. This is particularly true when the decision is a morally ambiguous one.
Outside of actual decisions, it is easier for someone to notice when their actions were not of their own volition. However, it still is never clear to them as to what exactly happened, other then that their body just seemed to move on it's own.