New York: The use of Facebook data to target voters has triggered global outrage with the Cambridge Analytica scandal. But the concept is nothing new: Barack Obama made extensive use of the social network in 2008 and stepped up "micro-targeting" in his 2012 re-election effort.
The unauthorized gathering of data on 50 million Facebook users by a British consulting firm that worked for Donald Trump has sparked intense debate on how politicians and marketers -- appropriately or not -- use such personal information.
But Cambridge Analytica, the firm at the center of the firestorm, has stressed it is far from alone in using data gleaned online to precisely target voters.
"Obama's 2008 campaign was famously data-driven, pioneered micro-targeting in 2012, talking to people specifically based on the issues they care about," the British firm said on Twitter.
Former members of the Obama team fiercely dispute any comparison to the Cambridge Analytica case, in which an academic researcher is accused of scooping up a massive trove of data without consent using a Facebook personality quiz, and transferring it improperly to the firm.
"How dare you!" tweeted Michael Simon, who headed Obama's micro-targeting team in 2008, in response to the firm.
"We didn't steal private Facebook profile data from voters under false pretenses. OFA (Obama's campaign) voluntarily solicited opinions of hundreds of thousands of voters. We didn't commit theft to do our groundbreaking work."
Jeremy Bird, a member of the 2012 Obama team, echoed those sentiments, warning: "Do not use the Obama campaign to justify your shady business."
But while Cambridge Analytica's methods for acquiring data are in dispute, the underlying goal -- using social media to take the pulse of voters and find those who are persuadable -- was common to both campaigns.
So-called micro-targeting, which borrows techniques from the marketing world, is as much about mobilizing voters and getting them to the polls as about changing minds.
And micro-targeting long pre-dates the internet, with campaigns as early as 1976 using this method, according to Victoria Farrar-Myers, a political scientist and researcher at Southern Methodist University.
Everyone who uses social media makes a decision to share some personal information, she says, although they "may not be fully aware of how people can utilize that."
"Being able to micro-target a voter down to what magazine they read and what issues might make them turn out does have an advantage for a candidate when they're running for an election."
"The Trump campaign did quite a good job at micro-targeting," she said, noting that it put a heavy focus on seemingly marginal localities that were identified as potentially winnable thanks to socal media, and ended up tipping Republican.
According to documents released by the Federal Election Commission (FEC), Trump's new choice of national security advisor John Bolton also hired Cambridge Analytica to conduct profiling work for his Super PAC fundraising group in support of Republican congressional candidates.
What remains unclear is whether the techniques made a difference in the 2016 US election.
Chirag Shah, a Rutgers University professor of information and computer science, said the data gleaned could have been instrumental to Trump's campaign.
"We know from other applications, not just in the political domain, but also all kinds of marketing commercialization domains that these things are very, very instrumental," Shah said.
"It is however speculative to say this really change the outcome of the election. All we can say is that, yes there were people who were influenced or targeted using this data."
Experts also stress that neither the Obama nor the Trump campaign broke any laws on the protection of private data -- or even Facebook's internal rules -- which were tightened in 2015 to prevent developers from collecting people's data without explicit consent.
Shah noted the concerns about improper use of personal data are not new.
"The problem is once people access the data from Facebook, for which they often pay, that data is out of Facebook's hands and out of Facebook's users hands.
"And there's no way that Facebook will be able to track all of the data being shared by third parties, fourth parties."
Rayid Ghani, a University of Chicago researcher who was chief scientist for the 2012 Obama campaign, defended his team's use of Facebook data while arguing for a need for better information that would allow users to know when and how their personal information is collected.
"The public needs to be aware of what data is being collected about them, what it is being used for, who it is shared/sold to, and what they're doing with it," Ghani said in a Medium blog post.