Let's talk a bit about tells - live poker tells.

A lot has been written about tells;  much of it quite silly, much of it quite wonderful.

I'm going to pass on the silly; no sense in giving anyone a reason to flame me.

Let's just give a nod to "the good stuff," of which there are two main progenitors: Mike Caro and Joe Navarro.

Book of Tells: Limited Utility

Mike Caro's Book of Tells outlined how particular classic tells are marked cards displayed.

The book was written relatively early in the poker explosion and shows its wrinkles, although much of the material is still relevant and useful to beginners.

Navarro's unique approach in Read 'em and Reap: A Career FBI Agent's Guide to Decoding Poker Tells (whew!) is newer, based on experience in the "real world."

In the course of his FBI assignments Navarro worked on techniques for detecting lying, subterfuge and misdirection. Unlike Caro's findings, Navarro's are based on scientific research.

If you're curious, Google "Paul Ekman" and follow the trail that emerges. Ekman is a distinguished psychologist who did much of the early work on how human emotions are expressed.

But, and this is the real topic of this article, it is only by integrating Caro's and Navarro's approaches that we can appreciate the real science of tells.

Caro's approach was developed through his years doing battle with some of the toughest opponents in the game.

It is knowledge that came from personal experience. As a result, it's difficult for beginners and even fairly experienced players to grasp what he is talking about.

For example, the "shaking fingers" tell for a monster hand is rarely seen these days.

The last time I saw it it was useless; the guy had a tremor that popped up whenever he felt stressed - which was anytime he put more than two BBs into a pot!

Read'em and Reap: Intuition Is Everything

Navarro's content is based on data collected from experiments on the patterns of reactions through which human beings express emotions and the ways in which experienced individuals come to learn to read those patterns.

These studies showed that well-trained individuals in agencies like the FBI and the Secret Service could spot suspicious activity better than ordinary folks.

They were adept at picking up on patterns of behavior, speech and movement.

Intriguingly, they typically did not consciously know what these patterns were; they only had a vague sense that "something's not right here."

In an earlier piece published on PokerListings I wrote about "intuition," that ability to know things we don't consciously know we know.

What Navarro is doing is trying to get the average poker player to hone his or her intuitive skills, to pay attention to the right cues in the poker world and learn to divine which ones are reliable.

Tells: Not What You Think They Are

But acquiring this skill isn't simple; it takes time.

Ironically, it takes the kind of experience Mike Caro had that led him to write his book.

The first thing to accept is that most tells are not picked up consciously. It is rare for a player to look at his opponent and know from some gesture, some movement that he is bluffing.

I spotted one once. It was so bizarre I thought it was phony marked poker.

This guy bet with his right hand, except when he was bluffing, when he bet with his left!

I only played with him a couple of hours so I never got to find out if it was a setup to trap someone like me or whether it was real, but in years and years of play, I haven't seen anything like it again.

There are a few well-known tells for stressful situations. One is the upward glance or the look at something irrelevant.

You'll see it when a player has made a big bet and now has to wait for his opponent to decide what to do.

He'll get nervous and, unable to hold a Hellmuthian or Fergusonian pose for long, he'll look at the ceiling, the TV, switch his gaze to a waitress walking past or even look briefly at his watch.

Most importantly, this is a sign of high emotion and you can't know precisely whether your opponent is aroused because he's bluffing or because he's sitting on a monster.

It's just like the so-called "lie detector" or "polygraph." It does not detect lies, it detects arousal - which is why evidence from the test is not admissible in court.

Putting Your Book-Learning into Practice

The typical tell is complex and psychologically interesting.

It is usually picked up subconsciously, intuitively and is based on the detection of patterns of behavior, action, speech and - most importantly - of betting.

We all have consistent manners of action, particular ways in which we function in particular situations. These are the marks, the revelations that a good poker player uses.

Tells are rarely specific; they are general, broad patterns of function.

The most common tell of a big hand is not some idealized way of sitting or a specific tone of voice.

It is the way a particular individual tends to sit or a tone of voice they adopt when they have a huge hand or are bluffing. One player may have a forward-leaning posture; someone else may tend to sit back casually.

To detect and read these tells correctly is not easy, and there is no magic bullet here.

It requires practice and experience - in the game in general and with this particular player.

In Search of the Twitch

Have you ever wondered why top pros like to ask players - particularly less-experienced amateurs - what their hand is?

Watch the next time a real master of this gambit like Daniel Negreanu does this.

He'll run through several possible hands he thinks his opponent might have. He's looking to see if there is any change in demeanor or "twitch" when he mentions a particular candidate hand.

This trick, for what it's worth, is one of the more useful in the quiver of the astute customs agent or CIA interrogator. Like them, Daniel isn't looking for a specific reaction, just one that is different.

The take-home message: it's that old one, "Practice, man, practice." You need to put in your hours.

The more time you spend at the game, the more you will develop a sensitivity to its complexities - even though you will be hard-pressed to tell anyone what you're learning.

And, of course, you also need to pay attention; players who focus on the game and what their opponents are doing build up their intuition faster and will learn to detect tells more accurately.