Social psychologist Stanley Milgram had questions about authority—in the scientific sense. More precisely, he had questions about obedience: Why do some people so willingly do what they’re told to do, and will they object or resist when they realize that their compliance might be hurting others?

His controversial 1961 study, which he devised to study and understand the “just following orders” psychology that enabled the Holocaust, monitored volunteers who were politely instructed to apply painful electric-shocks to a subject strapped to a chair whenever he answered incorrectly. That set-up was a ruse: the volunteers were the ones actually being tested, and Milgram found that 65 per cent of them were willing to zap the subject—an actor pretending—with shocks that would’ve been fatal.

Milgram’s findings became a major news story, and his life and research are now a Sundance movie. Peter Sarsgaard plays Milgram in The Experimenter: The Stanley Milgram Story, which chronicles the controversial obedience research and his subsequent projects, including his Small World social networking experiment (the basis for “six degrees of separation”). Winona Ryder plays Milgram’s wife, Sasha, and Anthony Edwards, Taryn Manning, John Leguizamo, Anton Yelchin and Danny Abeckaser play oblivious subjects of his most famous experiment.

In this first-look exclusive video clip, Sarsgaard narrates as Manning struggles with the experiment’s moral dilemma.

The Experimenter, directed by Michael Almereyda (Hamlet), premieres at the Sundance Film Festival on Jan. 25.