WASHINGTON — A former Facebook product manager who turned into a whistle-blower gave lawmakers an unvarnished look into the inner workings of the world’s largest social network on Tuesday and detailed how the company was deliberate in its efforts to keep people — including children — hooked to its service.
In more than three hours of testimony before a Senate subcommittee, Frances Haugen, who worked on Facebook’s civic misinformation team for nearly two years until May, spoke candidly and with a level of insight that the company’s executives have rarely provided. She said Facebook had purposely hidden disturbing research about how teenagers felt worse about themselves after using its products and how it was willing to use hateful content on its site to keep users coming back.
Ms. Haugen also gave lawmakers information on what other data they should ask Facebook for, which could then lead to proposals to regulate the Silicon Valley giant as it increasingly faces questions about its global reach and power.
“I’m here today because I believe Facebook’s products harm children, stoke division and weaken our democracy,” Ms. Haugen, 37, said during her testimony. “The company’s leadership knows how to make Facebook and Instagram safer but won’t make the necessary changes.”
After years of congressional hearings on Facebook and other large tech companies, Ms. Haugen’s appearance stood out not only for the inside look but for the way she united Republican and Democratic lawmakers around tackling the issue of the platform’s harm to teenagers. Some senators called her testimony a “Big Tobacco” moment for the technology industry.
The lawmakers said Ms. Haugen’s testimony, and the thousands of pages of documents she had gathered from the company and then leaked, showed that Facebook’s top executives had misled the public and could not be trusted.
“This research is the definition of a bombshell,” said Senator Richard Blumenthal, Democrat of Connecticut, who led the hearing.
Ms. Haugen’s testimony to the Senate Commerce subcommittee on consumer protection capped several intense weeks of scrutiny for Facebook after she leaked thousands of pages of internal documents to The Wall Street Journal. The newspaper’s coverage last month set off one of Facebook’s worst public relations crises since a data privacy scandal in 2018 with the consulting firm Cambridge Analytica.
On Sunday, Ms. Haugen’s identity as the whistle-blower became public when she set up a personal website and appeared on “60 Minutes.”
Facebook has repeatedly pushed back on the criticism, saying its research was taken out of context and misunderstood. On Tuesday after the hearing, the company defended itself by questioning Ms. Haugen’s credibility. Lena Pietsch, a Facebook spokeswoman, said Ms. Haugen had never attended a decision-making meeting with high-ranking executives.
“We don’t agree with her characterization of the many issues she testified about,” Ms. Pietsch said.
Lawmakers were in broad agreement during the hearing about the need to hold Facebook to account. They raised a variety of legislative proposals, including bills that would force companies like Facebook to provide more transparency on the spread of misinformation and other harmful content.
“The tech gods have been demystified,” said Senator Roger Wicker, a Republican of Mississippi. “The children of America are hooked on their product. There is cynical knowledge on behalf of these big tech companies that this is true.”
But the senators didn’t provide a clear path for addressing the many problems raised by Ms. Haugen. Dozens of bills on data privacy and changes to speech laws have stalled in Congress. House lawmakers approved a series of bills meant to strengthen antitrust laws this year, but the full House has not taken up the legislation, and its prospects in the Senate appear dim.
Ms. Haugen suggested legislation that would force companies like Facebook to open their systems to researchers to study the prevalence of hate speech and other harmful content.
“We can afford nothing less than full transparency,” Ms. Haugen said, who added that she did not believe antitrust action to break up Facebook would address core problems in the business model. “Left alone, Facebook will continue to make choices that go against the common good.”
Though the title for the hearing was “Protecting Kids Online,” lawmakers peppered Ms. Haugen on a wide variety of issues. They asked how Facebook had amplified dangerous speech leading to the Jan. 6 Capitol riot, how misinformation about the coronavirus and vaccines spread on its services, and how false information contributed to ethnic violence in Ethiopia and Myanmar.
Ms. Haugen gave detailed answers and repeatedly said executives knew more about the problems than they were letting on.
She also offered technological expertise on the technology behind the company’s services. She talked about the dangers in the way that Facebook gives priority to posts based on how many likes, shares and comments they generate. She contrasted it with iMessage, Apple’s text-messaging platform, which ranks messages in the order in which they arrived.
In addition to promoting harmful, hyper-engaging content in the United States, Facebook’s engagement-based ranking system is “literally fanning ethnic violence” in places like Ethiopia, she said.
Ms. Haugen also criticized Facebook’s focus on technology tools to detect vaccine and other misinformation. Facebook is “overly reliant on artificial intelligence systems that they themselves say will likely never get more than 10 to 20 percent of the content,” she said.
Several senators excoriated Facebook’s chief executive, Mark Zuckerberg, for making decisions that eschewed safety and privacy. Mr. Zuckerberg approved of promoting posts that generated the most engagement.
“So here’s my message for Mark Zuckerberg: Your time of invading our privacy, promoting toxic content and preying on children and teens is over,” said Senator Edward J. Markey, Democrat of Massachusetts.
Mr. Blumenthal said after the hearing, “Facebook is a black box, and Mark Zuckerberg is the algorithm designer in chief.”
Ms. Haugen studied electrical and computer engineering at Olin College and got a master of business administration degree from Harvard. She then worked at Silicon Valley companies including Google, Pinterest and Yelp. She left Facebook after nearly two years handling counterespionage as part of the civic misinformation team, according to her personal website.
At Facebook, Ms. Haugen said, she noticed a pattern of the company’s choosing to ignore warnings of harm done by its service. The final straw came in December when the company disbanded her group, which was charged with stopping the spread of misinformation.
“It really felt like a betrayal,” Ms. Haugen said.
In addition to sharing the documents with lawmakers and The Journal, she sent some to the offices of at least five state attorneys general and the Securities and Exchange Commission. Lawyers at Whistleblower Aid, a nonprofit law group that represents Ms. Haugen, have pressed the S.E.C. to open an investigation that Facebook withheld evidence that would affect its financial performance.
Mr. Blumenthal said after the hearing that he would ask the Federal Trade Commission and the S.E.C. to open investigations into Facebook for “a number of misleading claims” that have been made to consumers, the public and investors. He added that Mr. Zuckerberg should appear before Congress.
“If he is in any way in disagreement with anything that has been said here, he’s the one that ought to come forward, he’s the one that’s in charge,” Mr. Blumenthal said.
Reporting was contributed by Mike Isaac, Sheera Frenkel, Ryan Mac and Kevin Roose.