I always figured that it was part of the problems with my autonomic system.
was when my own hair startled me. I saw a lock of hair fall down, or sway back and forth, out of the corner of my eye. And just for a split second I thought, "what's that moving over there? there's no one home!" I felt very stupid.
My husband has startled me so many times that he now makes sure to make some small noise (cough, shuffle, something) rather than walking into a room without me noticing (he can be surprisingly quiet!). And he always calls me before he comes home so that I will know when to expect him. So, yes, spouses can be trained.
The fact that he trained himself is both sweet (that he cares so much, does not want me to be startled and feel those horrible after effects) and sad (because I HATE that this is another example of a change/burden that has been brought by this damn illness).