This definitely belongs to the never try this at home department.  Better yet, never try it.  That is, never try it until you must.
 
My husband and I were driving along the cliffs in the Atacama desert admiring the magnificent views and the goats scrambling up and down ledges.  We stopped at a lookout. It was dead calm. My husband was making a motion to get out when I screamed,  "Whatever you do don't go near the edge." Moments later a huge updraft came out of nowhere. "I could have been blown of the cliff" he said In a calmer tone than I would have used.
 
He was calm.  He has a sense of balance and that rare mix of adventurousness and caution, I was the one who was rattled.  My mind was spinning with wild spiderman recovery tactics.  "If you ever fall over a cliff try to catch an updraft and ride it to a ledge" was my plausible advice.  I am the acrophobic in the family.  Not in normal living but on cliffs and mountains.
 
This story is not the ravine run. Its just an appetizer for the main course.  Just in case my husband's adventurousness should get ahead of his caution, I did some survival research.  I had some intuition that everything you ever heard about acrophobia is wrong. Why the waviness, the spooky urge to jump, the startle reaction.  Nature, unlike Hollywood, is not interested in producing special effects for the hero's demise. Anxiety may contribute to acrophobia, but I've been anxious for math tests and I never saw way lines. Not once. And if we had an urge to jump our ancestors would have jumped to extinction and the issue of acrophobia would be mute.  Why a ravine when a bathtub would provide ample opportunity for disaster? Why does  this wooziness seems to disappear in planes where there is no connection to the ground.? Why do even non-acrophobics waver more on a 10 foot platform? The Pleistocene huntress in me called survival  mechanism and I was on the trail.
 
I remember a dream where I was falling and I heard a voice saying "break the fall", "break the fall". I sometimes wonder if dreams are virtual reality simulations where we can practice survival tactics. On a hunch I asked my husband if he thought anyone had ever recovered from a fall of a cliff by ratcheting to safety.  It seemed at least marginally more plausible than the updraft idea. To my astonishment, he  said, "Oh yes, that's how I took a fall from a 120 foot ravine and landed safely on my feet."  He said this in the detached tone normally used for analyzing Jack Nicklaus' latest serve.  He has the deadpan style down.
 
He once lost his footing hiking alone on a ravine. All of a sudden, he was falling. Time went slow-mo, suggesting an autonomic nervous system takeover. Apparently the jump reflex took him to the nearest ledge on his feet He briefly regained his balance, deflected and carried his momentum to the next ledge in a switchback motion. And so on, all the way to the abyss on his feet without a scratch! He felt not a moment of fear through all this surrealistic ballet. He looked up at the ledge and said in his understated way "Close call."  I guess.
 
I suspect that a club called Ciff Fall Survivors would have few members.  For all practical purposes it's a one of. But since you'll probably never see another case like this, lets analyze it. Several things were in his favor.  He was young, in shape and with excellent balance.  He was in control, no wavy lines, no spooky voices from his midbrain.  The jump reflex kicked in at precisely the right instant and the takeover by the midbrain was smooth.  The cortex is way too slow to negotiate the ratchet maneuver.  Another critical factor was that he fell on a ravine, not a cliff.  Not as in sheer drop, Our Pleistocene ancestors were not cliff dwellers. They evolved on the savanna. Cliff gazing would have been a bad idea anyway.  Your enemy would be too likely to sneak up on you and push you over before you  had time to worry about acrophobia.. But our ancestors may have negotiated ravines from time to time as they hunted. At times they lost their balance and recovered. 120 feet is a stretch but 10, 8, 6? .Their tunings, however, would be set to "lets get back before nightfall and sabertooths are out", not "be careful, it's a cliff."
 
At the Chilleno cliff, however, my husband needed an acrophobic at his side for ballast.  It was a calm day, no wind, no apparent reason for alarm.  However acrophobics believe at some visceral level that God made pigeons for perching on cliffs  I sensed danger.  I gasp to think I may have saved his life!
 
My take on acrophobia is that the spooky symptoms occur when information is coming at you so fast that the signalling in the brain loses synch. The brain is processing so fast that it can't weave the signals from various parts into a single coherent signal. At this point you start eavesdropping on the neurophysiology of your brain. You hear your midbrain signal time to jump. Your cortex fires back no way.  The wavy lines are proposed trajectories for the ratchet maneuver. You think you are going crazy.  If so you might want to check the working of your cortex.  What ever gave you the idea you ought to be standing over a 6000 foot drop?  In my experience as a motion control engineer, I've seen this signal uncoupling.  In control processing its called stalling.  The rule of thumb is, if there's a particularly weird bug, check the timing . Well I've got a conjecture that would explain the dizziness.
 
Hiking on a trail, your visual cortex continually searches for a trajectory ahead.  No wonder you become confused at a cliff. Your mind is frantically searching for a path to ground. Your engine stalls. You feel an out of sync impulse to go forward.  You gasp.The motor impulse is tuned for a trail but it is mismatched to a cliff situation. Anxiety desensitization and facing your fear can only go so far.  It may free up some brain cells that are tied up with the anxiety loop, but as anyone with a credit card knows, at some point maxed out is maxed out. "Think happy thoughts and you can fly" doesn't work.
 
If you don't believe this model, and I don't blame you, you don't have to.  With modern tools like PET scans and VR we could  safely check how the brain responds to height. I bet the visual cortex would become more and more swamped as the height increased.  The eyes would track the best path to safety. If any of you have "ratchet ride" recovery stories, I invite you to share them. We may find that cliff dwellers have a tendency to shift the upper body, tightrope walker style, rather than jump to balance.
 
We owe this to the so called "wimps".  Some people may not have the nervous system tunings for cliff walking.  John Wayne was brave but he had a canny survival instinct.  Some of the "face your fears" rhetoric may be a bit overheated. 
Sometimes, the prevailing message almost suggests that acrophobia is some kind of character flaw.  If you want to try some daredevil stunt who am I to say no?  Some Japanese couples celebrate their engagement by sharing a puffer fish dinner.But don't base your decision on a sales pitch or a misunderstanding of how the nervous system works. If someone calls you a wimp, stand tall, look them in the eye and say "No, I am a canny survivor."
 
I may be wrong. But to paraphrase Einstein, if I knew I wouldn't be a researcher.
 
IMPORTANT DISCLAIMER: These ideas are pure speculation.  IN NO WAY should they be construed as medical or safety advice.  Consult specialists in these areas for advice.
 
 
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