Mother's watch
Miranda is wearing her mother's watch all the time. She even refuses to adjust the time on it. While on the surface being a symbol of a daughter missing her mother, the significance of the watch goes beyond that. It is a symbol of Miranda's inability to escape the fate of being a copy of her mother, grandmother and great-grandmother and her fall into the hands of tradition, symbolizing the loss of her identity. Miranda even symbolically swallows the batteries of the watch at the end, to poison herself, and surrender to the house.
Coat mannequin
Miranda has a warped image of herself. She doesn't even recognize her reflection when she looks into the mirror; she can't see herself. The mannequin is a symbol of this failure to see herself clearly. It's important to consider the appearance of a mannequin. It is faceless, lifeless with no trace of identifiable features-which is what Miranda is on the way of becoming by losing traces of her identity.
Supernatural
The supernatural elements are building blocks of the plot of the novel, but they are not the main focus. They are rather understated to enhance the psychological effects and intensity of Miranda's deterioration, her inability to battle her eating disorder and her loss of identity.
