Today’s post is a bit different than what I usually share, but it’s an important topic.

It is well established from laboratory experiments, that emotional states can be transferred to others via emotional contagion, leading people to mimic – unconsciously –  expressions and emotions, positive or negative.  But can they spread in an online social network?

In 2012, between 11 January and 18 January, Facebook researchers conducted an experiment on about 680,000 Facebook users, to see if it was possible the updates in their news feeds to affect their mood.

Facebook used a technique called A/B testing, a popular method for figuring out the best online promotional and marketing strategies. It is used extensively from companies like Google or Amazon to test over some fraction of users and see how people react.

The participants in the experiment were randomly selected based in their Used ID and, without their consent.  Their news feeds were manipulated; half of the participants could see more “negative”, and the other half more “positive” stories. Negative and positive posts mixed in at random.

The results showed emotional contagion. The people who had positive content reduced in their news feeds, produced more negative posts. When negative content was reduced, people produced more positive posts.

The conclusion of the experiment suggested a massive-scale emotional contagion via social networks. The emotions expressed by our ‘friends’, could influence our moods, without even knowing that it is happening.

Facebook enormous power to affect what we learn is already known, but now its algorithms can also affect how we feel. They can impose certain opinions, shift our preferences, as individuals, as consumers and, as voters. Without even knowing it.