That's a pretty good question; wish I had an answer for it. I don't think there's a simple rule of thumb, but I guess if you're finding yourself wondering whether your characters are caricatures, then there's a good chance they are.

I suppose it's about knowing your characters and knowing how and why they react to the pressures of your story. I always try and remind myself that a character always views their own actions as justified. Understanding how they can justify their own actions theoretically protects me from caricaturing them (though my success is a matter of opinion).

When you say that you're describing or representing a person's attributes, are you perhaps telling inappropriately? Sometimes showing a character's actions under pressure makes them seem more rounded, even if the implications are relatively one-dimensional (i.e. hero acts heroically, villain acts dastardly).

That's about all I can think of, not sure whether it's helpful at all.

*Edit* Just saw Nate's reply below mine and it's a great one. Whether it's hero or villain, I always try and understand where my characters are coming from. Good or bad, they've all got valid reasons for doing what they do.

Regards,

Nick

Which is to say, it's all about contempt. With your characters, you care about them enough to find out who they are. Caricatures you start out mocking and disliking. You can't find out anything about them because it's all tainted.

A good example is the movie Hamlet 2. Every single character in that movie was a caricature, because it was obvious the writers, the director, even the actors themselves despised the characters they were creating. You couldn't get to know them, you couldn't like them, because there was nothing there but contempt.

It's like Ender's thing. You can't truly know someone unless you love them. Even the villains, the evilest of your characters, have motivations and desires. They have a past and they want to have a future.

I think the answer can be found in one of the quotations InarticulateBabbler posted in the "interesting sayings" topic:

"A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects." - Robert A. Heinlein

With Dickens while there may be exaggeration, and while his characters become extremes in some cases, they never become just an exaggeration. They aren't just a big nose and ears, so to speak. They are a face with inquisitive eyes and a wry smile that happens to have a large proboscis.

I think that it is alright to go into detail on features, physical and personality wise, and even exaggerate as long as your character doesn't become just the exaggeration. As long as they are not hollow underneath. They should still be able to do all of the things on Heinlein's list.