So my thoughts are running in three (I think...let's see...) related (I think related) directions:

• starting with a definition of proprioception, from Nature 432 (Nov. 4, 2004): "...the body's sense of posture and movement relies on different types of tiny receptors densely packed in the muscles and tendons. In 1906 Charles Sherrington coined the term proprioception (perception of one's own) for the sensory modality based on these receptors and called it our 'secret sixth sense'....proprioception provides information on the physics of the body....these complex calculations not only guide body movement, they also measure the geometry of external space."
• juxtaposing it with a description of what a friend (a racehorse vet) was certain were "proprioceptive deficits" : "A chestnut hurricane, Category Five, the sick filly instantly has a top speed above 135 mph...the two year old...departs the stall in a low graceful forward roll...stopped by the opposite block wall....she lands tail-first, and keeps thrashing....she has uncoordinated tremors and contractions, definitely of neurological origin, horrible and fascinating to witness."
• and with some musings by an art history student who read a portion of our on-line conversation: "for me performance art is often about the human need to act out atrocity not in order to 'not feel' it but to feel it even when it's not happening and to know that what goes on in the world-space we all inhabit is much more complex and multiplicitous than any individual space that we inhabit at a given moment. sometimes performance art can enact the narrative of history....sometimes performance art can stop time for a bit or remind us of that which happens more in circles and cycles rather than in a linear way? Performance allows things to go back and across."
• ...led me to hazard this answer to my earlier question: why insist on viewers re-experiencing atrocity in performance? For a heightened, constant awareness of the danger, not only of the obstacles of the outer world, but of the unreliability of the one within. Performance art demonstrates the atrocity of life, its constant impingement on that temporarily homeostatic/ carefully put-together thing we call "self." It performs the multiple ways in which the boundaries we construct to keep ourselves out of harm's way (a proscenium arch, a horse's stall) do not--will not--hold.