Nora is Torvald's "doll" in their house. He refers to her by diminutive pet names such as "little squirrel," "little spendthrift," and "singing lark." The macaroons he forbids her to eat represent her deception: she lies to him, forges her father's signature, etc. Playing hide-and-seek with her children, whom Nora regards as "dolls," is also symbolic of her relationsihp with her husband. The tarantella that she dances is a dance meant for couples, but she performs it alone, suggesting the deterioration of their marriage, just as the Christmas tree, which is fresh at the beginning of the play on Christmas Eve but on Christmas Day is already bedraggled. Even the hairpin she breaks by trying to unlock the letter box to retrieve Krogstad's letter shows her desperation and perhaps the loss of her traditional femininity, eventually revealed when she abandons her family. Such an ending was shocking to Ibsen's audiences who believed that a woman should place husband and children above her own needs and desires. That slammed door symbolizes her break with tradition in her quest to discover who she is as an individual.
I have not seen where any of the studies has mentioned this. One of the biggest symbol is that Ibsen uses the bird and squirrel names Torvald calls Nora in a way to make Torvald look silly and kind. However, I it is used to such an extent that I feel Ibsen is trying to emphasize that it makes Torvald feel superior. Therefore giving him control over Nora and she begins to feel helpless and small and unable to take care of herself, actually she even uses it to get what she wants, because she knows that Torvald likes to play the big man. He also uses this bird to teach Nora to obey: Helmer. Nora, Nora, and you would be a party to that sort of thing? To have any talk with a man like that, and give him any sort of promise? And to tell me a lie into the bargain? Nora. A lie--? Helmer. Didn't you tell me no one had been here? (Shakes his finger at her.) My little songbird must never do that again. A songbird must have a clean beak to chirp with--no false notes! (Puts his arm round her waist.) That is so, isn't it? Yes, I am sure it is. (Lets her go.) We will say no more about it. (Sits down by the stove.) How warm and snug it is here! (Turns over his papers.) He is a controlling man and I think that Ibsen wanted to show this. Torvald only has one friend (maybe) and he has told Nora that Mrs. Linde is a bore, etc, limiting her friends. He also continually calls her names “featherhead” : Helmer. What are little people called that are always wasting money? Nora. Spendthrifts--I know. Let us do as you suggest, Torvald, and then I shall have time to think what I am most in want of. That is a very sensible plan, isn't it?
and so forth. She was the perfect wife, because her father was the same type and had trained her to follow the rules. Think as I do, act as I want you to and we will have no problems.