There are several kinds of reasons humans may have an innate sense, in fact a biological and genetically encoded imperative, for recognition of rocks which have been gathered or modified by other humans. Examples include:
1) identification of other contemporaneous humans (threats or potential mates) in or near the same geographic space
2) identification of nearby suitable tool stone resources
3) identification of stone tools which are immediately available for reuse or repurpose
4) identification of areas which may good for exploitation of local resources (site habitation, paths of animal migration, seasonal plant foodstuffs, etc.)
5) in the case of examples of culturally originated visual forms, detection of specific information which may encoded in art objects as stone "exograms," or external information storage devices like today's post-it notes
These perceptions and assignment of significance to objects are assisted by our cognitive faculties of pareidolia, apophenia and hierphony.
These intuitive observations which are experienced broadly by non-formally trained persons seem to be intellectually killed by the field of archaeology because of its institutionalized and protected knowledge which has become faulty in a case of déformation professionnelle. The knowledge is mostly all etic (R. G. Bednarik, link on right sidebar) or involving analysis of external cultural phenomena from one's own cultural perspective rather than from a more neutral or empathetic position.
The biases of the discipline of Archaeology cannot prevail over the observations of astute laypersons in the long run, with more free association of images and ideas on the internet as opposed to the closed publication systems in anthropology and their thorough inability to process anomalous artifacts and information.
There is no other academic pursuit than archaeology which has had so many of its major twists and turns and developments and advancements assisted by amateur observers. Despite this, there is still an institutionalized disposition against the portable rock art question- largely pushed by amateurs since Jacques Boucher de Perthes in the mid 19th century. Without any changes and given enough time, the mast of the archaeology discipline will grabbed away from it by those with more functional and open systems of knowledge generation.
The several hundred well intended and intelligent individuals who have contacted me over the years regarding visually significant objects found in concentrated areas have been treated by professional archaeologists as "misguided" or "cloud watchers" or "pareidoliacs" in every case. This kind of patrolling of ideas is seen in cults, not in academic disciplines. Archaeology may defer to the hard sciences when it is convenient but in no way yet adopts the Scientific Method for its own core functions and operations.
Jacques Boucher de Perthes was eventually vindicated on the tools he noticed, later to be accepted as Acheulean handaxes, the most common human artifact in the world after the Mode I modified cobble. Soon enough, he will be vindicated too on the question of pierres-figures, or figure stones, existing right alongside the tools.