Their purpose was to validate and reinforce partisan viewpoints and to keep the inhabitants of each of these social bubbles in a constant state of anxiety over outcomes that could interfere with their beliefs. The most extreme were vituperative outpourings of hate speech.
New Zealand is unlikely to experience the extremes of fake news during the 2017 campaign. Our small and relatively integrated population provides a diminished environment for a Big Lie to take hold.
We have limited exposure to the extreme politics and, one hopes, the ground on which hate speech can take root.
While there will be disaffected individuals who attempt to use the fake news phenomenon to spread extremely warped ideas, there is little evidence of the extremes to which populism gave vent in the Northern Hemisphere.
We are probably too small to attract the attention of the Macedonian fake news creators who made easy money from Facebook and Google advertising during the US presidential campaign...or the attention of the devious cyberwarriors of the Kremlin.
We are far more likely to see a version of fake news that operates at a lower level of intensity: Distortions and embellishments of facts - together with some plausible falsehoods -- that are designed to heighten anxiety levels and push voters away from the centre ground toward more fixed positions.
This fake news will appear on blogs and social media, interposed with authentic material that gives it the appearance of fact.
It will trigger a chain of emotional responses - interest, followed by annoyance, followed by satisfaction that what you thought of "the other lot" was right all along.
These items of fake news will not be isolated. They will be part of a series designed to work progressively upon an existing belief to amplify and reinforce it.
Fake news has gained a reputation as a tool of the far right, witness the investigation of Marine Le Pen's Front National in the lead-up to the final vote in the French presidential election.
However, it works just as effectively at the opposite end of the spectrum. It is, after all, one of the established tools of propaganda designed to use emotions to cloud rational thinking.
British Conservative MP Damian Collins has called fake news "a threat to democracy". He chaired a House of Commons inquiry into fake news until it was discontinued as a result of the snap election.
Scott Ludlam, an Australian senator involved in a similar enquiry across the Tasman, has described it as "very targeted, co-ordinated and well-resourced efforts to undermine democratic processes". So how will New Zealand electors cope with such an insidious phenomenon?
Our mainstream media will have two principal roles to play. They must guard against becoming unwitting fake news accomplices and must independently verify information before they publish it.
And they must call out - name and shame - fake news creators and give the lie to "alternative facts".
The New Zealand public, for its part, must be vigilant. Last year the Annenberg Public Policy Centre's FactCheck Project published a list of ways to detect false news: Check the source and author, read beyond the headline, search the websites of quoted sources, look elsewhere and so on.
A more problematic entry on their list was "check your biases", difficult because we don't always recognise or acknowledge our beliefs.
Nonetheless, one of the best protections against fake news will be to ensure that our heads and not our hearts do the thinking.
• Dr Gavin Ellis, a media commentator and lecturer in media and communications at the University of Auckland, will be conducting a public panel discussion on fake news and the 2017 general election next Thursday, June 8, from 4.30pm in the university's Science Centre (38 Princes St).
