there is a lot of confusion about this,
My understanding is: (I have no idea if it is right or wrong, it's just how I feel it is)

It is about emotions/empathy and about density in a way.
if you remove the d from the scale, and say , on this earth most people score around 3 on the scale, some score 4 or even 5, since they have a higher understanding and a deeper connection to the "source" or "god". they can feel alot more than other people can feel and have labeled them selves (enlightend) this is by no means ment as a score system, that these people are better than those that are at 3, it has nothing to do with that.

it's more like this, the people at 3 run around with shades on, those at 4 have removed the shades in a way, not making them better or superior, but just making the perspective more clear in a way.

this world is 3d, we are all 3d.
some can manifest themselves in what they call the astral plane, moving in a non physical body, this could be considered an extra dimension.
don't worry about the dimensions, focus on getting in touch with yourself, learn to respect,love and have compassion for all things, I don't mean that you should run around shouting I LOVE YOU! to everyone you meet, simply treat them as friends :o)

understand that dying in this 3D world is not a game over, its simply a new start, don't fear it, but don't rush it for your self or others!
and basicly, believe what YOU wan't to believe, what makes sence to you, never just accept something without thinking or "feeling" about/on it, no one should make up your heart or mind for you!