Ms. Shriver criticized as runaway political correctness efforts to ban references to ethnicity, gender or sexual orientation from Halloween celebrations, or to prevent artists from drawing on ethnic sources for their work. Ms. Shriver, the author of 13 novels, who is best known for her 2003 book, “We Need to Talk About Kevin,” was especially critical of efforts to stop novelists from cultural appropriation. She deplored critics of authors like Chris Cleave, an Englishman, for presuming to write from the point of view of a Nigerian girl in his best-selling book “Little Bee.”

Ms. Shriver noted that she had been criticized for using in “The Mandibles” the character of a black woman with Alzheimer’s disease, who is kept on a leash by her homeless white husband. And she defended her right to depict members of minority groups in any situation, if it served her artistic purposes.

“Otherwise, all I could write about would be smart-alecky 59-year-old 5-foot-2-inch white women from North Carolina,” she said.

Ms. Shriver donned a sombrero for much of her speech — an allusion to a case in the United States in which articles of impeachment were drawn up (and later rescinded) against non-Mexican student government members for doing the same during a fiesta-themed tequila party at Bowdoin College. To frequent laughter from the audience, Ms. Shriver warned that the anti-cultural-appropriation movement that began in America had already reached Britain — where she lives most of the year — and might be headed to Australia.

Actually, it seems to have already arrived. In the middle of Ms. Shriver’s speech on Thursday night, an Australian writer of Sudanese and Egyptian origin, Yassmin Abdel-Magied, got up and walked out, making live posts on Twitter about her dismay at what she described as “a poisoned package wrapped up in arrogance and delivered with condescension.”