This summer, Ayad Akhtar was struggling with the final scene of “McNeal,” his knotty and disorienting play about a Nobel Prize-winning author who uses artificial intelligence to write a novel.

He wanted the title character, played by Robert Downey Jr. in his Broadway debut, to deliver a monologue that sounded like a computer wrote it. So Akhtar uploaded what he had written into ChatGPT, gave the program a list of words, and told it to produce a speech in the style of Shakespeare. The results were so compelling that he read the speech to the cast at the next rehearsal.

“Their jaws dropped,” Akhtar said. “It had preserved the speech that I wrote, using those words in such fascinating ways that it was astonishing to everybody there.”

Ultimately, Akhtar used only two of the chatbot’s lines. But his attempt to mimic A.I.-generated text — an oddly circular process of a human imitating a computer’s imitation of a human — had an uncanny effect: Downey’s delivery of the final speech feels both intimate and strangely disembodied.

“It’s the one secret lie that Ayad tells in the whole play,” Downey said, sitting on the edge of the Vivian Beaumont stage, where he, Akhtar and the play’s director, Bartlett Sher, gathered recently to talk about “McNeal.” “The only thing that isn’t true about this play is that A.I. wrote the final speech.”