Focus on the center of a cupule and watch it transform into a sphere
Because many of these artifact features have no apparent use as "nut cracking stones," "paint cups," or "grinding hollows," the often cited "meaning" or "purpose" for them by North American archaeologists, I wonder if cupules may have had some other, important, function. Having used visual focal points such as the cupule/dome, concave/convex, illusion in the past for my own self-hypnosis purposes, I wonder if they may have been used to invoke or enhance brain trance-states, meditation or self-hypnosis, in prehistory. The two photos above both "work" for me to achieve the alternating concave/convex perceptions. Perhaps you can experience the "cupule as convex" illusion too. Focus on the center of a cupule and watch it transform into a sphere. Imagine the cupule is a dome, globe, or planet.
The "cupule as dome or sphere," rock art convex/concave illusion, and cupule purpose and use as a "stone mantra," are first described here at portablerockart.com, according to my amateur, internet-based, research to date. I do not seem to have access to all of the source materials more readily available to academic researchers but will continue to work on the cupule subject as a layperson.
"The hollow face illusion," described here, also applies to cupules (domes), according to amateur archaeologist Ken Johnston
Take a look at visualfunhouse.com, altered reality section, hollow face optical illusion. The same visual principles of perception and illusion can operate with cupules according to Johnston
"To: Ken Johnston
Date: Wed, 20 Apr 2011 21:40:46 -0500
You can use my name/location if you'd like... my name is Jake Dixon and I live in Knox County, Illinois which is where these were found. They were found 1 mile apart from another in a creek. This is my "hotspot" while arrowhead hunting and typically find artifacts that people have labeled to be an Archaic site with some possible Paleo artifacts as well. Let me know if you need addtional pics or information... it's scary how similar these 2 rocks are in regards to the size and depth of the hole.
Could these have been used as portable meditation stones, or "mantra stones?" The meditative practices could have developed in the "old world" on fixed stone surfaces, such as in caves or along with petroglyphs on stone walls. A highly mobile population could have adopted this practice and used portable stones to meditate in multiple places or in places where no fixed stone surfaces exist.
Duncan Caldwell, Paris, France, identified an "optical illusion" of the European Upper Paleolithic, in 2010, of an elephant/bovid polymorphic sculpture which can viewed alternately as a European bison and a mammoth. Identification of the cupule as convex, or cupule as a dome, optical illusion associated with certain pitted stones, or cupules, (Johnston, 2011), would make cupules/domes the world's oldest optical illusions if they were intended or recognized in prehistory. Cupules are dated to as early as the lower Palelolithic, from 290,000 to 700,000 BCE. They could be then also the earliest figurative art- they are representations and reflections of spheres which activate when the illusion is perceived. It is a symbolic transformational process from cupule to dome which may have been given cultural signification by human ancestors. The cupule illusion phenomena may demonstrate an acknowledgement of knowing something may also be or mean something else- even "opposites" like a cup and a dome. Because they number in the many thousands, on 5 continents, cupules are the ubiquitous optical illusions of prehistory.
nationalgeographic.com, "Worlds oldest optical illusion?" bison/mammoth artifact, could be replaced by the cupule/dome illusion which, if recognized at the time they were made, pre-dates it by a couple hundred thousand years, Johnston says
Thanks go to Jake Dixon for his identification of two pitted stones from Knox County, Illinois, and for allowing us all to see photos of artifacts which could have been used as portable mantra stones.