Not too long ago I was engaged in a great conversation with a very nice, very interesting guy. Although I was enjoying the conversation and I was focused on what we were talking about, and I was engaged in the conversation, at the same time I had in the back of my mind that I was heading home in a few minutes, which I was looking forward to, and also I knew I had a long drive ahead of me and as more time went by there was a greater chance that I would get stuck in traffic. During our conversation, at one point I noticed that my right foot was a little further away from my body and it was pointing towards my car which was parked behind me and to my right. Being aware of my own body language, I realigned my feet to point in the direction of my conversational partner and finished our conversation appropriately, and then went on my way.
The subconscious mind is very powerful and it impacts our behavior, however most people don't recognize what other people's body language is saying let alone what their own body language is communicating to other people. I didn't intentionally move my foot in the direction of my car; it was my subconscious concern about my drive home, being late, hitting traffic etc. that changed my physical stance.
Such subtle behavior is important be aware of in ourselves as I did in this circumstance, so we can adjust our posture, behavior or other movements to ensure that our verbal and nonverbal behavior is saying the same thing! Failing to do so in this situation may have left my friend feeling like I wasn't interested in the conversation or that I didn't want to talk with him, which was not the case at all, which is why I realigned myself.
Picking up on these subtle behaviors in other people is important as well. In social situations like the one I mentioned above, if you notice similar behavior in the person you're talking with you can say something like, "Hey, I know you have to get going, but let's pick a time and get together again" or something like that. This may address their subconscious concerns and give them an easy out if they are anxious to leave.
In professional settings, like a detective during a police investigation or an insurance adjuster looking into a fraud claim, picking up on this behavior is crucial to interviewing success. It's important to see if you have rapport and engagement while interviewing a witness or victim, so if their feet (or even just one of them) are pointing away from you, you don't have their full engagement yet, or there may be something else going on you need to address. If you are talking with a potential suspect and his/her body shifts and the feet point away from you or towards the door on a particular question or at a particular point in their story, that is a strong signal that maybe they want to get out of there and avoid that area, topic or question, which would be your signal to focus on that spot further!
They key is context as well, recognizing that such behavior may not be only related to deception, but they in fact may be running late to get home too! The first thing is to be aware of it and then to address it and find out why the behavior was present during the conversation. You can't address what you don't recognize, and without proper training most people miss what other people say and do as well as what their own bodies are saying.