Well, I think I'll start answering this question. In the last couple of posts, I have stated that it is not a unique ability. In fact, it's a practice, not an inherent skill.
Why don't you ask yourself if you think you know what reality is. I'm referring to something basic, something that we can all agree with. Is there such a thing?
Lost because it wouldn't fit through the door of my new apartment was the Couch. I was sad when the movers had to donate it to a good home, because that sofa had taught me something truly useful. It was a giant brown couch. Or a giant purple couch. It's color actually depended upon the observer. My son and many of his friends would swear on a stack of bibles (or at least their current favorite DM manual) that the sofa was purple. To me, it was brown, brown like dark chocolate.
What color was it "really"? It should come as no surprise that different people have different experiences of the external world, but I was certainly surprised that this effect extended to basic visual characteristics of things. The discussion of whether this is a sensor problem or a processor problem is left to a future post. The take-home lesson is that your world and my world are not the same.
This effect was initially tested by Daniel Simons and Christopher Chabris at the University of Illinois with a movie that is a classic test of selective attention. It proves that if you're focused upon one characteristic of a scene, you might (many people do) fail to see strange and amazing things in the scene that you HAVEN'T been told told to monitor. The youtube link above contains this video clip.
So, I think that we can agree that we are unable to gather and process all the data presented to us, at least in part because of our focus. We focus on our jobs, spouses, children, pets, hobbies. This to us is "reality." In order to experience the rest of the data that we collect, but are not aware of, we must change of focus. This is not rocket science. Depending upon how deeply we are engaged with what we consider to be physical reality, it may not be easy to change your focus, but it is SIMPLE.
I propose to start discussing the development of the ability to sense the invisible with a simple exercise.
For an entire day, decide to experience every sound without a clear origin as being a message from a disincarnate entity. Your rational mind will hate this, most likely, so be intentional about the way to talk about it to yourself. "What if that sound means a spirit is trying to send me a message." "That faint buzzing sound might be an angel appreciating these flowers in my temple." Don't spend any time trying to convince yourself, just entertain the possibility. Lightly, if possible. Treat it as an experiment.
Like I was saying in a previous post, there's a huge spectrum of information that we're exposed to every day, some of which we can't sense (parts of the EM spectrum, for example) and some parts that we can process (only a small part of our experience is used to derive our notions of "reality"). This little experiment may help to un-glue you from whatever you're used to paying attention to, and open your senses to something a little different. Some of you are doing this all the time, for others it could be the first step into a slightly enlarged world.
Blessed be thou.