Precognition is a variant rule designed to speed up gameplay, particularly in games with more players. Players draw their new tile immediately after their turn. They do not reveal the tile to the other players until their own turn comes around. This rule gives players a chance to plan their move while the other players take their turns, and potentially speeds up the game.
When playing with the Abbey and Mayor expansion, a player may play his Abbey even if he has already drawn a normal tile. That tile is then kept until his next turn when he must play it.