You have a built-in sensory and analysis system that checks the actions and responses of those you communicate with. Such factors as pheromone release, voice timbre, blood flow under the skin and the like are constantly monitored. To be reliable the target must be physically present, a phone conversation or ethereal ghost cannot be analyzed.
While the Stress Analyzer is active, you are almost impossible to cheat, deceive or lie to. You can penetrate most disguises, discover lies and spot other attempts at deceit. Anyone trying to use {Skills/Deceit] against you cannot use an Action Value higher than their Charisma unless using some special means (such as drugs, cybernetics et. al.) to hide his bodily reactions.
Magical disguises and tricks, such as Illusion are similarly hampered, while true transformations, such as from ShapeShift orPolymoprhism are not.
A Shroud makes you immune to a this system.