What is the perception of black hole?

There have been numerous studies on black hole study but  referenced for the most part as depth perception and most of the studies have been conducted on babies and toddlers. We have never found a study specifically called the Black Hole Study as it pertains to dementia and elderly. But yet the Black Hole Study is reference or mentioned in many articles, Blogs and books but we can not find this study or any information about this study. Much research that mentions Depth perception cautions the use of putting something dark such as dark tile. dark caret, dark mat etc in front of the door because it may cause undue fear of falling which may work for the moment when you don't want the person to cross that area. But what about when you do need the person to cross that area and exit and they refuse or fearful of falling, regardless if you have now removed the darkened material.  An alternative for exit control would be camouflaging the door and there is much research and suggestions for this concept. 

Mr.Mohammed Ashraf has added quite an interesting perspective to this one!

I agree with Mohammed Ashraf Director of International Business ( Business Development )

agree with answer given by mr. Mohammed Ashraf