The author mainly uses indirect characterization. In the story, Mr. & Mrs. White's personalities, are revealed through their actions, speech and thoughts. For example when Mr. White acquires the monkey's paw from Sergeant Major Morris, he believes that he will be able to handle it and produce positive results.
"Mr. White dropped it back into his pocket, and placing chairs, motioned his friend to the table. In the business of supper the talisman was partly forgotten, and afterward the three sat listening in an enthralled fashion to a second instalment of the soldier's adventures in India."
"If the tale about the monkey paw is not more truthful than those he has been telling us," said Herbert, as the door closed behind their guest, just in time for him to catch the last train, "we shan't make much out of it." (Jacobs)
Even Herbert's personality reveals that he doesn't believe the stories that the Sergeant Major has told, he is eager to try out the wishing process.
When Mr. White makes his first wish, he gets a taste of the evil nature of the monkey's paw, but it does not stop him from using it again.
"I wish for two hundred pounds," said the old man distinctly. A fine crash from the piano greeted the words, interrupted by a shuddering cry from the old man. His wife and son ran toward him. "It moved, he cried, with a glance of disgust at the object as it lay on the floor. "As I wished it twisted in my hands like a snake." "Well, I don't see the money," said his son, as he picked it up and placed it on the table, "and I bet I never shall." "It must have been your fancy, father," said his wife, regarding him anxiously." (Jacobs)
Even Mrs. White's character is revealed through her speech, she does not believe that her husband actually felt the monkey's paw move when he wished, she tells him that he imagined it.
Clearly, the Whites take on the mystical powers of the monkey's paw with a degree of arrogance regarding their ability to control the outcomes and the potential consequences. They learn the hard way through great loss that the Sergeant Major was actually right!