Congress is starting to show interest in prying open the "black box" of tech companies' artificial intelligence with oversight that parallels how the federal government checks under car hoods and audits banks.

One proposal introduced Wednesday and co-sponsored by a Democratic presidential candidate, Sen. Cory Booker, would require big companies to test the "algorithmic accountability" of their high-risk AI systems, such as technology that detects faces or makes important decisions based on your most sensitive personal data.

"Computers are increasingly involved in so many of the key decisions A...