Deep Insight
Numerous hidden stats existed in RML that the vast majority of players were unable to see. There were simple hidden stats like Mass, which determined a player's total weight with the inclusion of their equipment. Therefore, even if two players had equal Agility stats, if one was wearing heavy armor while the other wore leather armor, the player in leather armor would hold the speed advantage.
There were also stats like Physical Strength that measured one's physical capabilities. And, of course, rare stats like Might also existed that allowed players to step into a new dimension of power.
The Perception granted by Song of the Siren fell into the same category as Mass and Physical Strength. It was a stat every player possessed from creation; however, it could not be viewed like other stats.