I have a friend, we'll call him Bob (since it's the only name he responds to) who I play poker with. Bob's a nice guy but he's not much of a poker player. If he's got a full house, I know it. If he's sitting there with the world's worst hand, I can tell. Do I cheat? No, not in this instance.
Bob follows patterns. For instance, if he's leaning back and looking upward like he's imagining how he's going to spend his vast fortune in the Bahamas and his body is relatively still, I know it's time to fold and cut my losses. If, on the other hand, Bob is upright, taps his fingers, fidgets and is generally active, it's time to bet the Christmas fund.
Bob is not subtle, that's obvious. But all people exhibit patterns like these in response to a given stimuli (full house). How could your Dad (Mom, teacher, spouse, bookie, etc.) know that you were lying just by looking at you?
They learned your patterns. Maybe it was the look in your eye, your shuffling feet, the cookie crumbs on your chin or something not quite definable, but they knew.
NLP looks for patterns and one of the earliest patterns noticed in humans was a tendency for the eyes to look in a certain direction when thinking in a certain way.
More specifically, people generally look up and to your right when thinking about a remembered image (Aunt Martha), up and left when constructing an image (Aunt Martha sitting on top of a flagpole), directly right for a remembered sound (Aunt Martha's gravelly voice), directly left for a constructed sound (Aunt Martha saying she's included you in her will), down and to your right when having an internal dialog with themselves ("Boy, I hate Aunt Martha") and down and left when experiencing feelings (experiencing how you really feel about Aunt Martha).
These only provide information about how someone is thinking not what they're thinking, an important distinction. So, what good is this? Good question, listen.
Example: If you are trying to convince your teenager to clean his room and every time he refers to his lack of interest in the subject, he looks up and to his right, he's probably constructing an image, possibly an unpleasant image of himself cleaning his room. If you continue telling him how nice it would feel to have the room clean, you're not likely to get far. You're trying to appeal to how it feels to have a solution when all he's seeing is a problem. You're not speaking the same language representationally. If you were to recognize this difference and tell him how nice his room would look with everything appearing neat you would have a better chance of getting some action out of him (were he not a teenager).
Recognizing whether someone is seeing, hearing or feeling, allows you to match the sensory system they're using and communicate with them much more easily.
More importantly, if you play poker with the same people again and again, you might begin noticing some patterns that might prove profitable.
By the way, it's wise to check to see if anyone at the table is NLP so you can abruptly switch your patterns (all's fair in love and poker).
Note: Watching someone's eyes and then referring to a chart often makes others nervous (at least in my experience), so I would suggest finding a friend and making an eye-accessing chart. Have them hold it in front of their chest and as they move their eyes around, call out the sensory system they're using. Getting the movements down usually takes only a few minutes.
Alternatively, if you happen to be able to use Shockwave files, you can use our Roving Eye (7K) exercise to learn.