An artificial intelligence hiring system has become a powerful gatekeeper for some of the most prominent U.S. employers, reshaping how companies assess their workforce — and how prospective employees prove their worth.

Designed by the recruiting-technology firm HireVue, the system uses candidates' computer or cellphone cameras to analyze their facial movements, word choice and speaking voice before ranking them against other applicants based on an automatically generated "employability" score.

HireVue's "AI-driven assessments" have become so pervasive in some industries, including hospitality and finance, that universities make special efforts to train students on how to look and speak for best results. More than 100 employers now use the system, including Hilton and Unilever, and more than a million job seekers have been analyzed.

On Wednesday, a prominent rights group, the Electronic Privacy Information Center (EPIC), filed an official complaint urging the Federal Trade Commission to investigate HireVue for "unfair and deceptive" practices. The system's "biased, unprovable and not replicable" results, EPIC officials wrote, constitute a major threat to U.S. workers' privacy and livelihoods.

Some AI researchers argue that the system is an unfounded blend of superficial measurements and arbitrary number-crunching that is not rooted in scientific fact. Analyzing a human like this, they argue, could end up penalizing nonnative speakers, nervous interviewees or anyone else who doesn't fit the model for look and speech.

The system, they argue, will assume a critical role in helping decide a person's career. But they doubt it even knows what it's looking for: Just what does the perfect employee look and sound like, anyway? Meredith Whittaker, co-founder of research center AI Now Institute, called it "a profoundly disturbing development."

Loren Larsen, HireVue's chief technology officer, said such criticism is uninformed and that "most AI researchers have a limited understanding" of the psychology behind how workers behave. "People are rejected all the time based on how they look, their shoes, how they tucked in their shirts," he said. "Algorithms eliminate most of that in a way that hasn't been possible before."

HireVue said the system is impartial. It said its board of advisers regularly reviews its algorithmic approach, but the company declined to make the system available for an independent audit.

Harwell writes for the Washington Post.