The question of Physical Seances and the reasons why phenomena only occurs in dark room conditions was recently discussed in a Psychical Research Forum. Kai Muegge of Felix Experimental Group had this to say when chatting with a researcher.
I believe it is righteous for you to say, that you do not get persuading evidence in the dark, that for you Light is needed.
I know a lot of people, including me, that have been present at Seances- in which supernormal proof was given, either Survival Evidence or phenomenological evidence – in darkness.
If people e.g. see self consistent movement of ectoplasm in good red light, materialized hands waving in good red light or columns of ectoplasm building up in the seance room, the proof thing has worked – for them!
Because let us be aware, that proof is ALWAYS a personal thing.
The moon landing was well documented, even though many think it was a hoax.
So to find conditions, that we can term as proof-giving for all will be very hard to achieve.
Furthermore as far than I know, Darkness is a certain condition, that is deeply connected with this part of Western trance Work culture. We know so many reasons, beginning with the observereffect, over psychological or mental effects and ending at several biological effects (photosynthesis), that seek for darkness.
Then there are the philosophical imlications regarding the occult – the whole word comes from the term “darkness” and there are many guides that tell, that darkness sets the human mind into the special condition, that make it receivable for the “Unseen”.
Furthermore controls have claimed, that that what happens in the dark cannot be grabbed completely by our cognitive system and because our awareness is built that way, that it fills out gaps in the perceivement with known matters, darkness is needed.
Here the danger develops, that sitters see things, that are not actually there (like an astronaut would do on the moon – after a few hours, maximum after one or two days, the human mind projects into the empty land of the moon known things from earth!)
That is because our mind is scompletely built for the range of perceivement of our 3 dimensional spacetime.
Moreover the entities claim, that the final proof won t be given to us easily and that “doubt”, like a the process called cognitive dissonance is permanently holding us in a reflective thinking process, that shall broaden our thinking processes and involve others to take part in the awareness process!