out of whack said:
No kidding. Witnesses, even reputable and respected members of society, are notoriously unreliable. I understand this is a recognized problem in criminology: criminal trials are strongly based on eyewitness accounts and unfortunately people have a habit of honestly believing seeing things that never happened, forgetting events that did and/or misjudging what they saw. Our mind seems to work to ensure that our perceptions are consistent with each other and it can be impossible to distinguish between images truly received and those that were self-generated. If a cat suddenly jumps sideways because of a static spark on its muzzle or whatever then the legs must be extended. But if the last direct (non-peripheral) image of the cat was in a recoiled position, this image could be the one retained by a witness. A different witness would not see the legs of a cat moving sideways in her general direction but could readily accept the testimony of the first one to the point of remembering seeing it too. And if both witnesses already believe that things move on their own in the house instead of being misplaced at times or nudged by a hyperactive cat at other times, well a spooky perception of events can result.
Neurologist Oliver Sacks once broke his leg running in terror away from an hallucination. He was hiking up a mountain where there was known to be a wild bull which had attacked people. He put that out of his mind, thinking the danger of an encounter was slim. However...
"I had, indeed, just emerged from the mist, and was walking around a boulder as big as a house, the path curving around it so I could not see ahead, and it was this inability to see ahead which permitted
The Meeting. I practically trod on what lay before me-an enormous animal sitting in the path, and indeed totally occupying the path, whose presence had been hidden by the rounded bulk of the rock. It had a huge horned head, a stupendous white body and an enormous mild, milk-white face. It sat unmoved by my appearance, exceedingly calm, except that it turned its vast white face up towards me. And in that moment it
changed, before my eyes, becoming transformed from magnificent to utterly monstrous. The huge white face seemed to swell and swell, and the great bulbous eyes became radiant with malignance. The face grew huger and huger all the time, until I thought it would blot out the Universe. The bull became hideous, hideous beyond belief, hideous in strength, malevolence and cunning. It seemed now to be stamped with the infernal in every feature. It became first a monster, and now the Devil."
A Leg To Stand On
-Oliver Sacks
Harper Perennial, 1984, page 20
(The upshot was that he turned and ran so recklessly away that he tripped down an incline and suffered a massive injury to one leg. The rest of the book is about, roughly, what it's like for a doctor to become a patient.)
Startle, not to mention outright fear, can do an amazing number on your perceptions.
She was still curled up in a ball.
Ok, well, actually I guess it would, but of a different kind. 
You're ruining my cat story.
