Allow me to let you in on several of our little secrets. It will likely lead to a silent shunning from my kind, but such is the price I choose to pay.
1) Make your point and stop talking
Most of observation is focus and the greatest inhibitor for us all is often ourselves. This is especially true for the extroverts that feel the need to contribute for the vast majority of the conversation. First, silently focus your mind on restraining your desire to think out loud. Next, continuously choose your battles and strategically make your contributions to the conversation.
2) Stop waiting for your chance to speak
This is where it really gets difficult, especially for us introverts. More often than not, people not talking are waiting for a pause in the conversation or, for those more impatient, a breath to be taken. As difficult as it may be, you need to train your mind to realize you're doing this and stop.
Now that you have a firm grasp of your tongue and mind, let me welcome you to my happy place.
As you know, most communication is non-verbal and therefore your sense of sight is crucial. These next techniques will teach you to hone your vision for observational purposes.
3) Watch how people speak
Our parents teach us to look people in the eyes when speaking, which is respectful, but not always necessary in a group setting. Honestly, someone's eyes don't tell you much. However, their facial expressions, where they are looking, the difference between the direction of their face and eyes, their posture, their arms, their hands and their legs all speak volumes. For example, someone that goes from a relaxed speaking position, to an upright posture, speaking with their hands and fervently looking everyone in the eyes is likely an extrovert thinking out loud that stumbled onto a topic very important to them. They are likely very emotionally attached to their point of view and likely to defend it vigorously. This is where the scientific method can be helpful. Make some assumptions, hypothesize what's behind those non-verbal cues and test your theories later on. Also, once a speaker relinquishes the proverbial podium stay focused on them for a few more seconds. The switch can provide very useful information. For example, an eye roll conveys their opinion of the new speaker.
4) Watch how people listen
Most people tend to focus singularly on the person speaking, going from one to the next and so on. Everyone in the room is always communicating. Even if someone is just starring at the speaker not moving an inch you can hypothesize that they are likely engaged and interested in what's being said. Scan the room. Others may not be as engaged.
5) Don't fixate on a single person
Eventually someone is going to notice you staring at them or potentially your use of these techniques as well. Either way, you need to shift your focus fluidly yet sporadically through the room. This is not necessarily just to avoid detection. Continuously shifting your focus, say every 3 to 5 seconds, allows you to observe more and likely pick up on more queues such as a shift in posture. Recently, I encountered a person that totally freaked me out by fixating on me. I was on a Hertz shuttle bus headed back to LGA and there was a guy sitting 15 degrees off directly in front of me. At first he was staring at my aggie ring, likely wondering what it was from. Next he stared me in the eyes which clued him into the fact that I was observing him, specifically his eyes. So there we were eyes locked. I thought to myself, I'll take this challenge and I'm not going to look away because I want him to know I know he was looking at my ring. After 5 seconds of him staring, which felt as if through me, I conceded and looked away. Either he was the better man or he was the creepy man.
6) Sit where you can see everyone
Once you're skilled in the previous techniques you will find yourself wanting to move to where you can see everyone. Avoid your natural tendency to just sit in the back of the room. Next time, get a seat at either end of the front row.
7) Use your peripheral vision
This is another technique that compounds on the previous. Once you've figured out the most probable general mental state of everyone in the room, start relying on your peripheral vision to notice changes in those mental states. This happens often when the speaker shifts. For example, most people tend to make large shifts in their posture, tilting their heads back or rolling their eyes when they grossly disagree or dislike the new speaker.
8) Look for patterns
People's distaste or opinion of others may manifest itself over the course of multiple body language changes, which may even escalate as the conversation progresses. Or the inverse, someone might sit up every time a specific person speaks. Your memory is crucial for this technique. Don't try to write this stuff down but typing can work if you can stay focused on the room as well.
9) Utilize other extroverts
The other extroverts have likely not made it past the second technique, so you might as well use it to your advantage. Statistically most of you think aloud, which if unguarded can be quite revealing. This tendency can be easily exploited to test your hypothesis. Use this sparingly and, of course, wisely.
As they say, the quiet ones are the ones you need to worry about. We are either deep in thoughtful consideration of the topic or have lost interest entirely. Identify the introverts in the room and make it a point to seek their thoughts on the topic at hand. If you like to plan ahead, request an inventory of everyone in the room's expertise on the topic early in the meeting to use later on to draw out introverts' relevant expertise and reflections on the matter.
11) Stay focused
Your mind is a powerful tool and if let loose it may wonder a bit. Stay focused. Your objective is to glean as much as possible from the conversation and if you stray there's no telling where you'll end up. You might find yourself alone in a dark room, yet such is the fate of the vast majority of this world.