Empathy, not Sympathy

[Black Rose]

I'm looking for a way to simulate empathy -- not the advantage Empathy, where you can "read" people and get a bonus to certain skills, but rather the state of actually feeling the emotions near you. To make this as open as possible, let's go for four levels:

• level one, where you feel the emotions of others with the intensity of the chill of a nearby iced drink (detectable, but even "disgusting" emotions are entirely tolerable unless completely saturated with excessive amounts of it, like being dropped into an operating death camp)
• level two, where you feel the emotions of others with the intensity of an icy can of whatever-you-drink in your hand (easily detectable, and likely to get annoying in a hurry if you don't care for the emotion in question)
• level three, where you feel the emotions of others with the intensity of plunging your arm into ice water, or getting nailed with a hose (strong effect, but surmountable with force of will in all but the most extreme cases)
• level four, where you feel the emotions of others with the intensity of falling through the ice on a lake (overwhelming, some sort of active countermeasure will need to be in constant use to remain sane)

This idea came to me and I just can't think of how to model it.