Honestly, I don't think the paranormal community does enough about this phenomena. It intrigues me so much that I incorporated into my book on Kindle and Nook "Josiah: Undead Cowboy."
Shadow people are a very odd phenomena with lots of theories. Here's the most typical features:
1. They can be seen anywhere, new home, old home, haunted, not haunted, park, public building...
2. They are first seen usually out of the corner of one's eye. When the viewer turns his head, he might see it whiz off or he might watch it a few moments before the shadow person perceives being seen and then startles and disappears.
3. They sometimes come with feelings of dread and doom to the viewer that is palpable, not just a fear reaction, but a sense of something bad about to happen.
4. They are often times seen as 3-4 feet tall, human shaped, completely opaque black as if they have mass. Sometimes, they are seen as tall and slender and are sometimes even reported with a top hat.
What if they are interdimensional and are used to being in our space, but when they see that we know they're there, they freak out and leave. It's like they're used to being unseen. Why are we sometimes catching glimpses of them? Perhaps modern day human eyes are changing. There are theories that fast refreshing screens on computers and TVs are making our eyes trained for things they hadn't been before looking at things in a natural world outdoors.
What if shadowpeople are harbingers? The first time I ever heard of the phenomena was at a SciFi convention I was speaking out. A Native American woman said, "I was in a hospital when I saw a little person who looked like a shadow. It was all black and not defined. It peered around the corner at me and a few times I saw it cross my room. I worried it might mean I was going to die." My son and his friend had a lengthy encounter with one in a graveyard. Others report them showing up in their homes during marital troubles and family issues. Are these terrestrial mothmen? Hmm...
This one is bantered around a lot. I have a lot of issues with this concept, the main one being, nothing freaking bad happens when they show up. If they don't want to be seen, you'd think a noncorporeal (a being that has never inhabited a human body) or a demon would be sharp enough not to be seen. They'd also manage to get their job done. When they show up, they'd do the dirty deed (whatever that dirty deed demons and noncorporeals are believed to do).
These continue to surprise us, especially because there is no particular place or person they show themselves for. It can happen to any of us, at any time. I have encountered 2 adult-sized ones and one short one and all 3 times, I sensed them before I even saw them. It was an odd feeling, as if you know someone is in the room and you assume it's a family member.
My son and his best friend had a very peculiar encounter in a graveyard. Mind you, my son is a gifted kid with a scientific and practical mind, but he knew his friend would be creeped out to go into a cemetery after dark. It was one I had a lot of weird things happen in. They approached the huge almost 2-story tall stained glass wall and both stopped. Something very dark was huddled next to the 4-foot tall altar. They assumed it was a homeless person, so my son took his camera and hit the button for the siting laser and it hit the object, showing that it was black and solid. It darted behind the altar. That shocked the boys because it was on 2 feet and just shorter than the altar. They rushed up to it and my son took turned on his flashlight only to find the altar was attached to the wall. There was no behind!
The boys both felt an intense feeling of doom and awful dreadful feelings. They rushed away, turned back to see it peeking around the wall at them with a human shape to it, no details, just place, and the boys ran through the cemetery where they saw it dart between some headstones.
That experience so upset my son's logical mind that he submitted a tryout for the first season of Ghost Hunters Academy and got a call from the producer as one of the top picks. We talked about his college studies and he decided to keep his scholarship, but he still wanted to know more. What were these things? How were they possible?
All we know that these things have in common is that they can appear to anyone, anywhere, not particularly haunted locations, and they bring with them often a feeling of doom or dread and when they realize they are being seen, they rush away. So, it would seem that we are being watched by something that does not like for us to know they are watching.
You might also like my upcoming post about Black-Eyed Children in relation to shadow people on Thursday.