Google's chief executive has expressed concern that we don't trust big companies with our data - but may be dismayed at Facebook's latest venture into manipulation

If Facebook can tweak our emotions and make us vote, what else can it do?

Around the time of the Indian election in May, a badly-headlined story began spreading which asked "Did Google affect the outcome of the Indian election?" The answer was no, it hadn't. But beneath the headline was an iceberg.



A non-peer-reviewed study, not carried out by anyone affiliated with Google, looked at the effects on undecided voters of tweaking the search engine's search results on different candidates - showing positive or negative results. Though not rigorous, it did highlight the possibility that if Google were so minded, it could influence floating voters, and so any close election.

Google responded that "Our results reflect what's on the web, and we rigorously protect the integrity of our algorithms. It would undermine people's trust in our results and company if we were to change course."

Larry Page, Google's chief executive, expressed his frustration last week with peoples' lack of trust in "big data" companies like his own. If only we would let companies mine our health data, we could save 100,000 lives every year, he argued. "We get so worried about [data privacy] that we don't get the benefits," he said.

Undermining the feed

Page, and others at Google, might therefore be unhappy at the way that Facebook is again undermining our trust. During a January week in 2012, around 700,000 English-speaking Facebook users were chosen, without their knowledge (or explicit consent) to be emotional lab rats. The researchers found that if you tweak what people see in their Facebook Newsfeed - the scrolling information on your page - to suppress or heighten certain emotional words, readers' emotions will shift to match.

It's not only emotions Facebook can nudge. It can make you vote too. On presidential election day 2010 it offered one group in the US a graphic with a link to find nearby polling stations, along with a button that would let you announce that you'd voted, and the profile photos of six other of your "friends" who had already done so. Users shown that page were 0.39% more likely to vote than those in the "control" group, who hadn't seen the link, button or photos.

The researchers reckoned they'd mobilised 60,000 voters - and that the ripple effect caused a total of 340,000 extra votes. That's significantly more than George Bush won by in 2000, where Florida hung on just 537 votes.

As the New Republic points out, what if Mark Zuckerberg - or some future Facebook chief - wants to influence a future election? The growing amount of data suggests that subtly influencing peoples' opinions, and voting turnout, could be engineered to prod voting in one direction or the other.

Fraud at polls?

It's hardly a new concern; Orson Welles described it in Citizen Kane, whose newspaper-owning proprietor seeks election victory through biasing the news he publishes. And the fictional Kane, of course, was based on the real-life newspaper tycoon William Randolph Hearst - who then used his influence to suppress Welles.

But what's different from the scenario in Kane is that we can't compare what we're seeing with anything else; these aren't biased newspaper articles, they're a sort of biased reality. If our friends all seem a little down, judging by their Facebook posts, or if we're being constantly urged to vote, we can't see the hidden hand behind it. Subliminal advertising has been banned in most countries for decades. Now Facebook, one of the few online advertising behemoths, seems to have reinvented it - for things which aren't exactly advertising. They're about how we feel about each other, and what we do.

That's a worry. Concerns about Google or Facebook biasing an election might seem far-fetched. But until a few weeks ago, the idea that a few people in California would set out to silently change how around half a million people feel would have seemed weird too.

The most worrying thing? That hardly anyone is surprised that this is possible. In which case, what are the limits of possibility in this tweaking of our online environment? Page may be dismayed at our lack of trust. But we keep being given reasons not to trust what happens with our data. There's no simple resolution - because even if these experiments stop being published, we can't be sure they'll stop.

• How does Facebook decide what to show in my News Feed?