How does Susan Glaspell use imagery in her play Trifles?

Most of the imagery in Glaspell's one-act play Trfiles centers around the Wright home, which is also the crime scene being investigated. The key images become the clues that the women—Mrs. Hale and Mrs. Peters—use to solve the crime, while their husbands come up empty using traditional investigative methods.
Mr. Wright has been murdered, and his wife is being held at the prison. The men who are investigating the crime scene bring their wives along to gather some items for Mrs. Wright. As the women look around the house, they notice several key pieces of evidence ignored by their husbands. First, they notice the kitchen work that Mrs. Wright left unfinished. The imagery of the unfinished canning is the first clue that something went amiss and also the first detail that kick starts the women's empathy with Mrs. Wright. The image of Mrs. Wright's knitting is another major image that also serves as a clue for the women. They notice that Mrs. Wright dropped a stitch in her otherwise perfect knitting, indicating her disturbed state of mind. The most significant images are those of the birdcage and the dead bird. These are the clues that seal Mrs. Wright's motive in the women's minds. They seem the damaged birdcage without a bird and then find the body of the dead bird. This bird becomes symbolic of Mrs. Wright, nee Minnie Foster. One of the women remembers her when she used to sing. They piece together the information in the house and past knowledge of Minnie to determine that Mr. Wright would not let her sing and killed her bird. That is what made her snap and murder her husband. The act of taking the dead bird with them also shows that the women are going to protect Minnie and they understand why she committed the crime.
These major images serve as clues to help the women solve the crime. Significantly, these items and details are also seen as "trifles" by the men, so they are not able to uncover Mrs. Wright's motive.