Number of Facebook friends linked to size of brain regions, study suggests

October 18, 2011, Wellcome Trust

Scientists funded by the Wellcome Trust have found a direct link between the number of 'Facebook friends' a person has and the size of particular brain regions. In a study published today, researchers at University College London (UCL) also showed that the more Facebook friends a person has, the more 'real-world' friends they are likely to have.

However, the researchers are keen to stress that they have found a and not a cause: in other words, it is not possible from the data to say whether having more makes the regions of the brain larger or whether some people are 'hard-wired' to have more friends.

The site Facebook has more than 800 million active users worldwide. Nearly 30 million of these are believed to be in the UK. The site allows people to keep in touch online with a network of friends. The size of these networks varies considerably, with some users having only a handful of online friends whilst others have over a thousand – however, whether this variability is reflected in the size of real-world social networks has not been clear.

Professor Geraint Rees and Dr Ryota Kanai explain their findings about the link between number of Facebook friends and the size of certain brain regions. Credit: Wellcome Trust

Professor Geraint Rees, a Wellcome Trust Senior Clinical Research Fellow at UCL, said: "Online social networks are massively influential, yet we understand very little about the impact they have on our brains. This has led to a lot of unsupported speculation the internet is somehow bad for us.

"Our study will help us begin to understand how our interactions with the world are mediated through social networks. This should allow us to start asking intelligent questions about the relationship between the internet and the brain – scientific questions, not political ones."

Professor Rees and colleagues at the UCL Institute of Cognitive Neuroscience and the Wellcome Trust Centre for Neuroimaging studied brain scans of 125 university students – all active Facebook users – and compared them against the size of the students' network of friends, both online and in the real world. Their findings, which they replicated in a further group of 40 students, are published today in the journal Proceedings of the Royal Society B.

Professor Rees and colleagues found a strong connection between the number of Facebook friends an individual had and the amount of grey matter in several regions of the brain. Grey matter is the brain tissue where the processing is done. One of these regions was the amygdala, a region associated with processing memory and emotional responses. A study published recently showed that the volume of grey matter in this area is larger in people with a larger network of real world friends – today's study shows that the same is true for people with a larger network of online friends.

The size of three other regions – the right superior temporal sulcus, the left middle temporal gyrus and the right entorhinal cortex – also correlated with online social networks, but did not appear to correlate with real-world networks.

The superior temporal sulcus plays a role in our ability to perceive a moving object as biological, and structural defects in this region have been identified in some children with autism. The entorhinal cortex, meanwhile, has been linked to memory and navigation – including navigating through online social networks. Finally, the middle temporal gyrus has been shown to activate in response to the gaze of others and so is implicated in perception of social cues.

Dr Ryota Kanai, first author of the study added: "We have found some interesting that seem to link to the number of friends we have – both 'real' and 'virtual'. The exciting question now is whether these structures change over time – this will help us answer the question of whether the internet is changing our brains."

As well as examining brain structure, the researchers also examined whether there was a link between the size of a person's online network of friends and their real world network. Previous studies have looked at this, but only in relatively small sample sizes.

The UCL researchers asked their volunteers questions such as 'How many people would send a text message to marking a celebratory event (e.g. Birthday, new job, etc.)?', 'What is the total number of friends in your phonebook?' and 'How many friends have you kept from school and university that you could have a friendly conversation with now?' The responses suggest that the size of their online networks also related to the size of their real world networks.

"Our findings support the idea that most Facebook users use the site to support their existing social relationships, maintaining or reinforcing these friendships, rather than just creating networks of entirely new, virtual ," adds Professor Rees.

'Understanding the brain' is one of the Wellcome Trust's key strategic challenges. At the Wellcome Trust Centre for Neuroimaging, clinicians and scientists study higher cognitive function to understand how thought and perception arise from brain activity, and how such processes break down in neurological and psychiatric disease.

Commenting on the study, Dr John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, said: "We cannot escape the ubiquity of the internet and its impact on our lives, yet we understand little of its impact on the , which we know is plastic and can change over time. This new study illustrates how well-designed investigations can help us begin to understand whether or not our brains are evolving as they adapt to the challenges posed by social media."

Explore further: Facebook rolling out 'smart lists' of friends

More information: Kanai, R et al. Online social network size is reflected in human brain structure. Proceedings of the Royal Society B; 19 October 2011

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3.7 / 5 (3) Oct 18, 2011
I don't subscribe to facebook because of security concerns. I guess that means my brain size is zero. I suspect this would not come at great surprise to my wife, but it is kind've a startle to myself.

1 / 5 (2) Oct 18, 2011
This must be the single biggest load of c___ coming out of neuroscience this year, and might well be on its way for the Ignobel 2012 awards. Hope there will be some serious injection of better sense in all this, or at least future avoidance of such gross, downright disgusting titles!
not rated yet Oct 18, 2011
The sample-size of 125 students, presumably all from the same university, is laughable to say the least.
not rated yet Oct 19, 2011
I had over 400 FB friends, I have no friends in real life. People like me, but I don't like people. I have social anxiety, I'm an anthrophobic. I guess this doesn't apply to all, but interesting...

Also, aren't 90% of people's FB friends BS anyways? I talk to like 5 of them in real life.
not rated yet Oct 19, 2011
More like an infomercial for Facebook. Bigger sample would be useful and perhaps members of other social sites.
not rated yet Oct 19, 2011
More stupid university research work -- no wonder after billions of dollars, we are still trying to find a cure for cancer and the common cold if this is the quality and standard of university research
not rated yet Oct 19, 2011
Having few Facebook friends mean I have much more of my brain available for useful stuff! :D
not rated yet Oct 20, 2011
Nobel scientists have discovered a link between people who use a toilet brush and IQ.
I think Intelligent people would throw this study in the toilet and flush it.
What a waste of time and money...
not rated yet Oct 25, 2011
The sample-size of 125 students, presumably all from the same university, is laughable to say the least.

so whats it mean if i married myself in FB?

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