Speaking at the Stanford Cyber Policy Center, Mr. Obama said the “new information ecosystem is turbo-charging some of humanity’s worst impulses” and deepening cultural divides.

The trend will get worse if more is not done to slow the spread of harmful content, the former president argued.

“Each of us, whether we work at a tech company or consume social media, whether we are a parent, a legislation, an advertiser on one of these platforms, now is the time to pick a side,” Mr. Obama said. “We have a choice right now: Do we allow our democracy to wither or do we make it better?”

“That is the choice we face,” Mr. Obama said.