There are a number of motifs in "The Open Window." It is the repetition of the motifs that adds to the suspense and creates the effect of what is seen through the open window. A motif is a noticeable recurring device such as a word, image, or verbal formula that catches your attention and helps build an element of the story, such as mood or suspense. The major motif is the open window of the title. This focuses reader expectation on this object, thus forming the foundation of suspense.
"You may wonder why we keep that window wide open on an October afternoon," said the niece, indicating a large French window that opened on to a lawn.
The group of motifs that is next in in importance are those surrounding the tree dead, lost hunters. These motifs tell the reader what to look for and what Framton will be horrified to look for and see: e.g., the three men, the little brown spaniel, the waterproof white coat, the guns under arms, and the words "Bertie, why do you bound?" Another most important motif is the verbal formula that is used for Vera: she is styled as "the self-possessed young lady." This description of her adds to the irony and helps to build the surprise ending and the equally surprising resolution.
Other motifs, like letter of introduction, shooting, nerve cure, and some people help to develop characters in very little space and to build a backstory and sense of setting.
"[H]is sister had said when he was preparing to migrate to this rural retreat; "you will bury yourself down there and not speak to a living soul, .... I shall just give you letters of introduction ...."