Readers of this blog will know that I believe awareness is the single most important part of self defense.
Now, I exist is a slightly more vigilant state than most. It's not quite paranoia, but I am always scanning my surroundings, scanning for potential threats. Military people, police and security can often be identified just by the way they scan any new bar, restaurant, store, subway car etc, that they are entering. I am guilty of this. My buddy called me on this not long ago when we were out at a pub. He got a kick out of observing me observe others. He wanted to know what I was looking for. He understood about exit points, potential weapons and that sort of thing, but wanted to know what I looked for when I scanned people.
That part is a bit trickier. In the example above, there were several dozen people in a fairly small pub. It wasn't too crowded but there weren't many empty tables.
So how does someone scan 30 people in a few seconds? I have, after all, walked out of an establishment based on a five second scan.
There are two things I try to hone in on. One is the overall energy in the place. No matter what you want to call it, if the place has a bad vibe or bad energy, I'll go somewhere else. I think most people have walked into a place and felt bad energy. Something about the place just didn't feel right. I say trust this. Unless you have to be there, leave. Trust you gut. Call it your sixth sense if you want.
If I'm scanning a room, my mind and my eye easily 'rule out' most people as a threat in an instant. It's those individuals that give off bad energy or intent that I take a second look at. I could walk into a bar filled with martial arts masters of the highest calibre and would most likely rule them all out as potential threats in a heartbeat, providing they were there with good intentions. That's the difference between intent and ability. The masters would have the ability to be a threat were they so inclined, but if they don't have bad intentions, I would skip right past them on my 'threat-o-meter'.
It is actually harder to break down all the different things that combine to give you a good or bad feeling about someone than it is to make the overall assessment.
With the exception of certain professions, it isn't even necessary to break it all down to explain it. Your brain processes all this stuff for you. The neat part is that it's a skill that can be used and improved by anyone in any walk of life. It can even be fun. Make a game of scanning the room wherever you go. Look for bad energy or intent. What's the worst that can happen? Nothing. The best? Maybe you avoid being present for an unpleasant situation, whether or not the bad intentions ever get aimed at you.
And remember, predators watch for victims that aren't paying attention. If they see you paying attention, they'll move on to easier prey.
Be safe. Have fun.