In exacting, scientific terms? Sure, maybe there isn’t a specific “dip” or “valley” that you can chart out. It might not be an exact thing.
I think the problem is the “valley” usage. Maybe Mori was wrong about it being a specific “dip” as you get closer to mirror-image human appearance and behavior. Maybe we’d be better off using other terminology to refer to the general concept of “The Uncanny”.
But one important thing to note is that Mori was writing with a characteristic Japanese style, and that he was making a sort of poetic comparison between the goal of designing robots that people found appealing and the effort of climbing mountains. Thus, in constructing that particular metaphor, the reference to valleys seems to have come along completely naturally.
