By DAVID KLEPPER (Associated Press) WASHINGTON (AP) — The powerful algorithms used by Facebook and Instagram to deliver content to users have increasingly been blamed for amplifying misinformation and political polarization. But a series of groundbreaking studies published Thursday suggest addressing these challenges is not as simple as tweaking the platforms’ software. The four research papers, published in Science and Nature, also reveal the extent of political echo chambers on Facebook, where conservatives and liberals rely on divergent sources of information, interact with opposing groups and consume distinctly different amounts of misinformation. Algorithms are the automated systems that social media platforms use to suggest content for users by making assumptions based on the groups, friends, topics and headlines a user has clicked on in the past.