This probably will not be a very popular belief here, but I believe there is a subconscious connection between human minds that allows humans to share emotions. I believe most humans have experienced this, but they usually dismiss these feelings as coincidence, or ignore them entirely. Unless you've personally experienced what I'm referring to, you'll probably dismiss this post as "mysticism" talk.
I started studying Taijutsu when I was 12-years-old, and early in my training I performed an exercise where I was sitting outside meditating (mentally picturing myself inside a heightened perception bubble, where I could 'feel' every blade of grass move) and my brother/instructor would sneak up to me and try to touch me on the shoulder. My goal was to raise my hand and point in the direction he was coming from right before he touched me.
After a couple years of this training, with regular meditiation, I eventually got so sensative that I could feel intention (feel the emotion of the person in question) through walls. One time I had a friend sneak into my yard at midnight, and I could feel his overwhelming desire to attempt to be quiet as he did it. I could feel him as he moved around my house, and I sort of followed him through the wall this way as he circled half the yard to make his way to the door to my room. Another time I was woken out of a sound sleep because I could feel someone standing outside the wall where I was sleeping (another friend who had come to wake me late at night).
Science cannot explain this phenomenon, and people who say that it is simply your mind picking up subtle conventional perception cues have probably not experienced the event deeply enough to dismiss this notion. Some animals hunt entirely by sensing tiny electrical impulses that build in the muscles of insects the moment before muscle contraction, and in this way they know when their pray is about to move. It is possible that humans can also sense electrical impulses in the brain, or magnetic polarity changes, or smell pheromones, etc. Regardless of how it happens, I am 100% certain that sensing another human's emotion is something a person can be trained to recognize. Even untrained people experience this, which is why when you're sneaking up behind someone it is important to remember to dampen your intention while doing it. You wouldn't want to be actively starring at their back and thinking, "I'm gonna get you..." If you did this, they would be very likely to inexplicably turn around and lock eye contact with you.
