I'm still not convinced to like this one (despite some rather cogent and intelligent arguments from other listeners).
I get that - according to the internal to the logic of the story - he's imprinting only on sight.
But the internal logic doesn't make any sense to me... why should imprinting only occur on sight? Isn't sound, touch and even smell just as much (or more) concerned with how a child connects to mommy and figures out who they are? How would it be possible to separate out those connections to only "reset" on sight alone?
But let's give a bogey here to the argument that "the creator of the opt wanted it to be that way."
Again, why?
If you're making an opt, why go to all the trouble to make the reimprint happen only at sight? Wouldn't it be easier and more total to make the child reimprint at any new physical stimulus from a person? And why would the opt creator go to all that trouble to make it only happen at sight and leave the apparently obvious risk (to me) that the child will innocently reimprint at sight, but be scared out of their gourd at the abuser/opt creator's voice or smell, which presumably doesn't reset and would carry over in their memory to associate with fear from one impression to the other? Isn't that completely at odds to their purpose?
I still argue that - even internally - it doesn't make sense, if one just takes a bit of time to think about it. The simple answer, to me, is that the opt creator simply wouldn't create an opt this way.
But the author would, because that the way it needed to be for their twist ending.
I'm all for twist endings, but not at the expense of the rest of the story. Too much was sacrificed on the altar of the twist, and I just can't abide by it.
With this society's level of modding I don't think it would be impossible to tie it only to sight. There's a whole section of the brain, the occipital lobe, dedicate entirely to managing sight. Seeing seems easy to us, but there's a whole lot of automatic interpretation and filtering that happens completely outside of our awareness. I work in computer vision, a very difficult field, and much of the difficulty comes from teaching a computer to interpet images in meaningful ways, images which are immediately obvious to a human despite our relatively slow processing speed. There's a lot of stuff going on up there to handle all the optical information. And I think if you restrict your tinkering to only the occipital lobe then I expect that sight would be the only one to be altered.
Some thoughts on WHY only sight:
1. If the mod was engineered for intentional child abuse, maybe it's part of the game. If someone got pleasure from a child's fear, then they could repeat the experience anew without the child ever being able to cope. I think sight would be a bit more reliable than sound because it seemed that his memory would not reset as long as the adult was IN SIGHT. But how do you create that same experience if you're dealing with voice-triggered resets? You can't just say his memory won't reset as long as the adult is IN HEARING because then what happens if the adult stops speaking for a while? Sight, being a passive sense makes more sense as a reset trigger if the reset is intentionally programmed.
2. We never found out for sure that this mod was intentional, I don't think. It could very well just be a botched mod intended to do something else. In which case the details don't have to be desirable to anyone.
So, in short, I think that this all makes sense in the context of the story, not just authorial tinkering.