Final answer:
The literary device used to describe Tessie's change of heart in "The Lottery" is irony, which is the use of words to convey the opposite of their literal meaning.
Step-by-step explanation:
The principal literary device used in Shirley Jackson's "The Lottery" to describe Tessie's change of heart about the lottery is irony.
Initially, Tessie is eager to join the lottery, worrying about being late to the event. However, when she is selected, her attitude shifts dramatically to protest against the lottery.
Irony is the use of words to express something contrary to truth or expectation and is employed here to highlight Tessie's drastic shift in behavior. It is a powerful device that demonstrates the theme of blind tradition and its consequences.