what is the psychoanalytical theme of the open window by H.H. Munro?

Though it is a remarkably short piece of fiction, "The Open Window" explores a number of important themes, including the difference between appearances and reality. It is no surprise that Mrs. Sappleton's niece tells a story that is easy to believe. She begins with an object in plain view, an open window, and proceeds from there. The window is obviously open, but as for why it is open, the reader is completely at the mercy of Mrs. Sappleton's niece's explanation, at least while she tells her story. The open window becomes a symbol within this story-within-a-story, and its appearance becomes its reality. When Mr. Nuttel and the reader are presented with a contrary reality at the end of the story, the result is a tension between appearance and reality that needs to be resolved. Which is real? Can they both be real?

Deception provides another key theme in the story. The action and irony of the story revolve around the apparent deception practiced by Mrs. Sappleton's niece. It remains to be seen, however, whether this deception is a harmless prank or the result of a sinister disposition. If the niece's deception is cruel, then the reader must question the motives behind the deception practiced by all tellers of stories, including Saki himself.

In addition, "The Open Window" shows us just how fine the line can be between sanity and insanity. Mr. Nuttel's susceptibility to deceit is no different from that of the reader of the story. Yet Mr. Nuttel is insane, and the reader, presumably, is not. To maintain this distinction, Saki forces his reader to consider the nature of insanity and its causes.