In "The Lottery", what message might the author be trying to convey to the reader through the treatment of the characters' behavior?
Jackson portrays the characters as rather routined people. She positions them to perform actions regularly performed by people in any society. In describing some of the different characters Jackson narrates:
Soon the men began to gather, surveying their own children, speaking of planting and rain, tractors and taxes. They stood together, away from the pile of stones in the corner, and their jokes were quiet and they smiled rather than laughed.
The women, wearing faded house dresses and sweaters, came shortly after their menfolk. They greeted one another and exchanged bits of gossip as they went to join their husbands.
Within these words, we have stereotypical actions of women and men. Jackson does this specifically to demonstrate that what is about to happen in this story could happen to any society. This includes any society (yours or mine) reading her words today! As the story continues, Jackson reveals her message by expecting readers to infer that while in a given society, it is difficult to see the traditions that are kept which hurt the society. The characters certainly show forms of uncomfortability, but they do not do anything about it.