We all feel schadenfreude. We certainly feel it vis-a-vis our enemies. And we may even be secretly gratified when a successful friend gets knocked back a peg or two (even though it may make us doubt our own decency). But we don't find it funny.
And we certainly don't find it funny when we witness a stranger have an accident resulting in, say, stitches. (Where is the humor there? Where is the irony, the unexpected ending, the subtle satire, the taboo truth?)
But the sociopath will find that hilarious. He'll cackle as you or I would if someone had just made an extremely funny joke.
But it's a very distinctive sociopathic trait. Non-sociopaths simply don't find this kind of thing humorous.
There's a great scene in Cape Fear where the sociopathic Max Cady, played by Robert DeNiro, picks up Ileana Douglas in a bar. She starts to tell a joke: "An unmarried woman meets a guy, and he tells her he’s just got out of prison. 'What did you do?' she asks. 'I hacked my wife into 52 pieces with a chain saw….'"
At this point DeNiro laughs uproariously, as if what Douglas has said so far is great cause for mirth.
Douglas then tells the punchline: "She says, 'So you’re single'?"
At that point DeNiro laughs some more, a little less enthusiastically, and says, "That's even funnier."
It was a subtle touch, one probably lost on most viewers, but Martin Scorcese, the director of the movie, knew what he was doing. Only a sociopath like Max Cady would have found the mere fact of a man chopping his wife up into 52 pieces funny.
Keep that in mind the next time you hear someone laugh at an accident.