The experiment attempted to manipulate people’s moods and emotions. It was tested on 689,000 Facebook users who knew nothing about it.

The test involved tweaking Facebook’s algorithms to show users news posts which were either mostly positive or mostly negative. They found that users who were shown negative reports then tended to post less positive things about themselves.

The test is now a legal matter. Regulators in both the UK and Ireland, where Facebook Europe is based, are to investigate whether the company has broken data protection laws.

Ostensibly, the experiment was a test of the power of social contagion within the internet culture.

The results were hardly surprising. Separate studies have already shown that even light use of Facebook use increases feelings of depression. This is thought to be because when we engage with social media we’re only ever given a window into the best lives of others.

Hardly anyone takes to Facebook, Twitter or Instagram to talk about the less attractive or boring parts of their lives. Reading the selectively entered posts of others, we can begin to feel less upbeat about our own lives.

The fact that other research has been carried out for the same result, however, doesn’t excuse Facebook’s methods. Reputable research is conducted with the full knowledge and consent of its volunteers, not behind their backs.

In times past, Facebook CEO Mark Zuckerberg has openly aligned himself with the thinking of Scott McNealy of Sun Microsystems, who famously said after September 11, 2001, ‘Privacy is dead, get over it.’

In an interview with TechCrunch magazine in January 2010, Mr Zuckerberg indicated that his company was now acting on the assumption that people want less privacy, given that they share so much about themselves online.

The problem with this thinking, of course, is that people may be sharing more about themselves, but they actually quite like having a clear measure of control over their information.

Facebook sometimes acts as if it should be the ultimate steward of that information.

This entire episode raises important questions about who owns our data online. Is it we the users, the social media companies, or someone else?

A secondary question is just as important: if we don’t own our online information, can it be sold by someone else for their own profit?

Facebook is not the only group that is has a cavalier attitude to its customers’ privacy. Google CEO Eric Schmidt was criticised a few years back for suggesting that anyone concerned about online privacy was trying to hide something. 

Since then, of course, the European Court of Justice has ruled that people have the ‘right to be forgotten’ by Google – and, presumably, by other search engines.

As a result, Google is setting up measures by which internet users can request the removal of certain information about themselves from search results. It’s revealing, though, that Google began to do so only when it was given no other choice.

Challenges to privacy are, by extension, challenges to personal autonomy and our ability to make free choices. Studies have shown just how highly susceptible human beings are to the pressures of social acculturation.

We may think ourselves totally independent thinkers, but the research suggests that we are heavily influenced by the prevailing norms around us.

Hence the modern preoccupation among politicos and advertisers with so-called nudge marketing. This involves the notion that entrenched human behaviour patterns can be changed by suggesting that alternative patterns have become the norm.

Sensitivity to peer pressure, it seems, is not something we completely grow out of once we leave puberty behind.

A level of control over our privacy is necessary if we’re to make good choices – or at least choices that are made after weighing the options for ourselves, rather than simply going with the flow.

Few of us will take the same care in judging a situation if we’re aware that others are looking over our shoulders, whether they be neighbours, politicians, bureaucrats, corporate heads or technocrats.

On the evidence to hand, Mr. Zuckerberg seems to be more careful with his own privacy than he is with those who use Facebook.

His personal life is not exactly regular magazine fodder and that is commendable and wise. Nobody, with the possible exception of certain criminals, should have their private lives made public without their consent.

It’s a shame Mark Zuckerberg doesn’t seem to rate his customers’ privacy as highly as his own. Most of them, after all, don’t have his money to spend on PR companies and media managers.

It’s time Facebook – and any similarly inclined companies – are brought to heel when it comes to treating their customers’ data as corporate property.