reply to post by MischeviousElf
Elf, thanks for putting that up, I'd stumbled across it before and forgotten. ALSO, to every one else, thanks too

!
This is a most enjoyable thread. I've always loved optical illusions.
ALL of these are fine examples as to why the concept of Human 'eyewitnesses' is fraught with compexity, and how people who 'witness' the same
event can have such differing interpretations.
The 'mask' example is a perfect illustration of why some people see "domes" in some Lunar photos, instead of craters. But, this is
not the
thread to belabor that....
These show how the Human brain, especially the visual cortex, in combination with the "design" of the eye, and retina, over millions of years of
evolution are far from 'perfect', but have adapted to suit our needs -- well, our
former needs as hunter-gatherers, for example. The
relatively recent development of modern life (since the Industrial Revolution) is challenging.