Are you talking about the blue dolls? I think they're there to show the effect that the world was taking on Ib and Garry. When you first enter that room as a group, you don't see the dolls, you see bunny rabbits. Mary and Ib think they're cute, but Garry is freaking out and wondering how anybody could think they were cute. In a bookshelf in the same room, there is a book talking about falling into insanity, experiencing hallucinations and not realizing that they're hallucinations. Ib had just entered the world and Mary was born in it, so neither of them saw anything strange, whereas Garry had apparently been there for god knows how long so it must've driven him pretty crazy. When you enter the room as Garry alone, you see the dolls and he acts like they were what he had seen all along, he doesn't remark about any rabbits transforming or anything. Later in the game, you see the blue dolls while Ib is in the party too, after she's gone through even more traumatic experiences.
This is mostly just a guess, but I think it was heavily implied. I thought it was a really nice touch.