Pricks and Stones

They (O.K., Harvard was involved) showed some "normal" people a video of a hand getting penetrated with a needle.

(Ouch!)

They hooked up their brains and . . .

Those who scored highest on the Psychopathic Personality Inventory (PPI) showed significantly less mirror neuron activity while watching this fright fest. 

But wait, there's more.

A nasty little subset -- those who scored highest on a particularly charming trait called "coldheartedness" -- gave the least damn about the whole "needle through the other guy's hand thingie," so the brain monitoring showed.

Again, these were not patients, malfunctioning psychopaths in jails or hospitals, just regular folk off the street. Your boss maybe. Your ex. 

Geez.