Beginner poker players may assume this only occurs when someone is attempting a country-western style bluff for all of the opponent's chips.
While this is partially true, an avid live poker player will tell you it's sometimes just as difficult to maintain your composure when you're praying for a call while holding the nuts.
The bottom line: regardless of the strength of your hand, your body has autonomic responses in high-stress situations. Despite your best efforts, it may be difficult to control them.
The mind and body, as Bono would say, move in mysterious ways. Without further Bono reference:
Top 5 most difficult body movements to control when an opponent is trying to read you
5) Twitchy Fingers. If you are asked something like how much you have behind, the higher degree of stress and increased blood flow may cause the fingers to tremble.
Not much that can be done to prevent this other than training yourself to lower your heart rate and breathing frequency in times of increased stress.
4) The Inadvertent Grin. When making a full or semi-bluff, it can be very difficult to control the sides of your mouth and eyes. Any movement here may help your opponent glean extra information about your holdings.
If this happens to you, the best solution is to act as if you meant to do it and give the guy the creepy Ronald McDonald stare. It's too late to retreat.
3) The Cracking Voice. Be sure to keep your words to a minimum and if it's not absolutely necessary to speak, don't. Keep your lips sealed.
If you are trying to disguise a bluff, one or two wrong words or changes in your inflection can tip off a strong player. On the contrary, if you are trying to induce a call, sometimes too much talk can unveil your confidence.
Normally it is best to stay silent and let the opponent know nothing about what you're thinking or, more importantly, how you're feeling.
2) The Shifty Eyes. For players who don't wear shades at the table it should be clear that even if you keep your head/body still, your eyes may be running rampant.
Depending on the player you are, if you try to force a fold by staring at someone, you may find that your actions are actually enticing the player to call. Whether your bet was a huge bluff or for value, you should keep your gaze calm and stationary.
Eye contact with the opponent may trigger the aforementioned "Inadvertent Grin."
1) The Gulp/Swallow. Even if it's just your weekly $5 sit-and-go, the tension in these situations can make it feel like your whole body is being suffocated by the largest boa constrictor on the planet.
It comes down to a one-on-one psychological battle and all you can think about is how, suddenly, you feel like you've been stranded in the Sahara without water for three days.
Then it happens: the Gulp. It's inevitable; just hope no one notices.
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