I don’t know if it even has anything to do with MS, as it first happened years ago, but occasionally - very occasionally - I look at my watch, and can’t understand it at all. It’s as if it was an alien device. I still know it’s a watch, and that I’m meant to be able to tell the time from it, but occasionally, I just stare at it, and it conveys no useful meaning.
It usually only lasts seconds or fractions of seconds before the spell is broken and I suddenly know how to read it again. I’ve never spent hours or a whole day unable to read my watch, but it’s very disconcerting when it happens, even for just a few seconds.
I’ve also occasionally been somewhere I knew well, but it was as if I didn’t know it, and I couldn’t find a commonly-used shortcut home. I’ve had to walk all the way round the long way. I went again a few days later, and found the shortcut exactly where it’s always been, and couldn’t understand how I’d got confused and couldn’t find it.
I do think this happens sometimes to otherwise healthy people, too. There’s even a name for it: it’s called “jamais vu” (“never seen”) - the sensation that a familiar place is unknown. It’s the opposite of “déjà vu” (already seen) - the sense that an unknown place is familiar.
Both are probably a glitch to do with memory recording and retrieval. As it (so far) only happens to me very occasionally, and has never lasted long, I’ve not even reported it to anyone. I think it happens about twice a year - perhaps not even that. I think tiredness and preoccupation play a part with me. It’s more likely to happen if my mind has been wandering to other things - I suddenly find I can’t make sense of the here and now!