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So, I really like this. Ksayer1, CC BY

Explainer: what is emotional contagion and can you catch it on Facebook?

Facebook has faced a storm of protest since it revealed that it had carried out a large-scale secret experiment to find out if it could make users feel more positive or negative by editing feeds to expose more “positive emotional” or “negative emotional” content. The researchers behind the study said they had shown that emotional states could be transferred to others through “emotional contagion”.

If you have ever been in a room with several babies, you would know that if one of them suddenly starts crying it’s bad news, because soon it’s likely to turn into a group crying event. From anecdotal reports, infant giggles seem to be equally infectious. Both of these examples illustrate a fundamental aspect of human empathy, which is termed emotional contagion.

Emotional contagion

At its simplest, emotional contagion refers to a set of processes which enable us to “catch” another person’s emotion. Most of these processes are largely automatic, so in order for me to experience being sad with you, I don’t need to explicitly know or work out the reasons why that is.

This in contrast to another vital component of human empathy, which is sometimes referred to as cognitive empathy, or “theory of mind”. Cognitive empathy is distinct from contagion in that it requires you to make an explicit set of inferences in order to know what the other person is feeling/thinking. It is generally believed that contagion is present from a very early stage in infancy, while cognitive empathy arises later on in development.

Theoretical accounts have proposed a working definition of emotional contagion as “the tendency to automatically mimic and synchronise facial expressions, vocalisations, postures, movements with those of another person, and, consequently, to converge emotionally.”

Smile like you mean it

In the laboratory, this is typically measured using behavioural observation techniques such as video coding of mimicry of body postures/facial expressions (as in studies on infants), heart rate measurement, as well as using psychophysiological techniques, such as facial electromyography (EMG) – which is able to detect minute contractions in facial muscles that are not detectable by eye – and galvanic skin response where our skin becomes better able to conduct electricity (due to increased sweating) in response to stimuli.

The zygomaticus major muscle, found on either side of the face, draws our mouth up into a smile. While studying emotional contagion in our lab we record activity in this muscle using EMG while participants are looking at videos of people smiling at them. A common observation from such studies by us and others is that the contraction of zygomaticus major is higher in response to smiles than in response to other emotion expressions.

Importantly, the extent of emotional contagion for happy faces depends strongly on how rewarding we find the observed person to be. People exhibit greater contagion for those who they like more, than those who they do not like. In this context “liking” someone is a proxy measure for how rewarding/valuable a person finds another person.

An important caveat here is that the facial measure in the smiling experiment above is not an index of how subjectively happy a person feels. Subjective experience of emotion depends on many other processes, not just on emotional contagion – and is notoriously difficult to measure. Our current techniques of measurement (using psychophysiology or neuroimaging) can’t answer the question of subjective experience, for example whether I am actually feeling as much joy as you when I see you smile and then smile myself.

The case of Facebook

Experimental approaches to studying emotional contagion have primarily used non-verbal stimuli such as facial expressions, body posture and vocalisations to capture the largely automatic nature of the processes. However, processing words, and presumably status updates used in the Facebook study, is arguably less automatic and would suggest the involvement of different, but related, processes. One such process could be that of conforming to group behaviour in order to fit in. But this kind of process would involve a more deliberate “working out” of what you could potentially post on your Facebook, so you don’t stick out as an odd one.

It is also important to bear in mind that emotional contagion, while being a fundamental part of human empathy, is not its only component. The full spectrum of human empathic abilities that allow us to understand and respond appropriately to others’ emotions relies on an elaborate architecture involving both emotional contagion and cognitive empathy.

Research into online social behaviour is at its infancy, and we still don’t know how closely processes involved in real-world social behaviour can be mapped on to the virtual, online domain.

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