Now a bit longer post about auras and how our visual system makes them.

They are not "hallucinations" as Little Hawk wrongly claims skeptics say (and only shows by that he doesn't know what he's talking about in a very verbatim sense). Hallucinations come from the central visual system and are not based on peripheral input. They are usually not shared, so if one person has a hallucination the others around can not see it.

"Auras" are input based and a result from the first few stages of neural processing. They are real in one sense of the word: Everyone with an intact visual system and the right instruction how to look can see them. The input into the central visual system is real (completely different from a hallucination) but has no physical correspondence in the outside world.

How that? Our viasul system has a 2-D input on a curved surface and must make 3-D sense of the input. From a long line of evolution, some "clever" wirings of the neural circuitry enhance contrast (by lateral inhibition). That makes a lot of sense for it helps to split up the visual array into different objects. So, at the border between two object (or object and background) the visual system exaggerates the physical difference in brightness, colour etc.

Artists know that or are taught how to use it. An artist who pencil-draws a sun on white paper knows how to make the white paper look whiter on the spot where the sun is. Like our visual system, the good artist shows the world not as it is objectively but as it is perceived subjectively. The artist exaggerates, makes thing longer, shorter, darker, lighter, larger than they are in the physical world in order that what we perceive when looking at the artwork is close to our perception of reality. (That's what is missing in boring photographs BTW)

Back to the visual system. Contrast enhancement will make the immediate surround of a body look different than the rest of the background. Then something else comes into play too. We always have microsaccades (tiny eye movements). They are necessary for seeing. With a completely stabilised eye (curare does a good job, unless you forget artificial respiration), after very few seconds we see nothing at all, we become functionally blind (those who have made it describe it as a scaring experience). If something now moves we can see the thing that moves but nothing else. The reason is that with a stabilised eye the borders between objects always fall on the same bunch of neurons and they adapt quickly. All our senses are triggered by changes, our visual system too.

Third factor is adaptation. All cells adapt that is they do not "fire" at prolonged input as they did in the first half second (That's why alarm mostly go doo   dooo   dooo   dooo...; one doesn't adapt easily to on-off stimulation. Partial adaptation of course is what mostly happens unless there is completely white light. That is one subset of neurons fires less than before and the other neurons that are not adapted still can fire full speed. That leads to afterimages at first in the opposite colour, and if you look longer it can change the colour due to the differential recovery rate of different neurons.

Now we have all we need: (1) eye movements (2) contrast enhancement (3) adaptation and afterimages. If for instance a prophet gives a sermon on a mountain the lower seated listeners will see him with a clear sky as the background. If he is good at what he does, they will listen and watch like spellbound and they will not take their eyes off him. If you look at any dark figure before a bright background, the immediate surround will after some time look brighter than the rest of the sky. To all of the onlookers! The prophet now has a bright halo around his head.

Why don't we see that normally. Because we switch attention and gaze too quickly for these effects to be seen. But if someone (something captures our attention so that we keep our gaze for a minute or so, we can see the brightest colours around persons (and inanimate objects likewise) chnaging in time. It is fun. I used to do it in boring lectures with the prof.

So that's what skeptics think about "auras", and not Little Hawks parody of a skeptic.

Wolfgang