Gwendolyn Reece, Associate University Librarian and Director of
Research, Teaching and Learning, describes this as a “problematic system
of recommendations that reinforces the echo chamber.” As Facebook uses a
preferential ranking algorithm to determine the content and order of an
individual’s news feed, that material narrows in scope to reflect the
biases of the user. Social media as a news source poses other problems
as well. When trusted colleagues or friends share news items, it is easy
to assume that the news story itself is trustworthy or that the sharer
has already vetted the source. The ease with which one can go on to
share that same story with their own network allows for a piece of
unsubstantiated information to spread widely and quickly. Assistant
Librarian Derrick Jefferson proposes that mindful analysis and
corroboration are two of the best tools to combat the spread of
misinformation, saying, “do not blindly accept a headline as a fact.”

(via Libraries and the Fight against Fake News | American University)