Human Brain Limits Twitter Friends To 150 | Hacker News Reader

Human Brain Limits Twitter Friends To 150

technologyreview.com

41 pointstokenadult15 comments

For those who may be interested in such things, the original paper is

Dunbar, R. I. M. 1992. Neocortex size as a constraint on group size in primates. Journal of Human Evolution 20:46--493

pdf: http://isites.harvard.edu/fs/docs/icb.topic514568.files/Dunb...

Also relevant is the follow-up paper published the following year, which extends Dunbar's argument:

Dunbar, R. I. M. 1993. Coevolution of neocortical size, group size and language in humans. Behavioral and Brain Sciences 16:681-735.

pdf: http://www.cogsci.ucsd.edu/~johnson/COGS184/3Dunbar93.pdf

That said, Dunbar's paper - and the entire concept of the "Dunbar number" - is the shoddiest piece of science I have ever seen. Dunbar arrives at the magical 150 by extrapolating from the neocortex ratio to mean group size correlation of nonhuman primates. However, the human neocortex ratio is 30% higher than that of any primate and the resulting "corresponding" mean group size of 147.8 is more than double the highest nonhuman mean group size of 65.5, which makes the validity of such a large extrapolation highly suspect. In an attempt to justify this, Dunbar gives a 95% confidence interval of 100.2 - 231.1 (quite a wide range), then sets out to find as many examples of real-world data as possible that fit in this predetermined interval. As is often the case when one knows exactly what to look for, it appears to be everywhere. My favorite moment is where he encounters Naroll (1956)'s observed maximum settlement size of 500 yet deems it "likely that the equivalent mean settlement size will not be too far from the value of 150 suggested by the above analyses" (Dunbar 1993 p687).

How are you supposed to go about falsifying an argument like that?

Edit: Better formatting.

Dunbar's number continues to be misunderstood. It is not so much a measure of individuals as a measure of relations between individuals that are important for us to track. It is not the node that is important, it is the connections that the node has.

AKA "the Monkeysphere", as described in this scholarly article: http://www.cracked.com/article_14990_what-monkeysphere.html

I don't have Twitter friends - just a list of people that I want to know what they are up to.

I also has friends who I follow on Twitter but I rarely if ever message them via Twitter. Thus according to this study, they wouldn't be my friends.

It makes sense to me that a person only has time and attention potential to manage a certain number of relationships. However, the number depends on the person and how deep those relationships are. Twitter is not a medium where it's time consuming to interact with someone, and the relationships, while revealing, are somewhat shallow. I don't think the Twitter reference makes sense.

The mean of my friend's Facebook friend count agrees. I noticed the ~150 before, interesting to see an explanation for this.

I remember when they said on facebook you can only keep track of 300 friends max. Couldn't find that old post but heres a similar Mashable post http://mashable.com/2010/01/25/brain-facebook-friends/

I guess the formula works something like

Max friends = (max message length) + 10

At least, it would make more sense than a number Dunbar pretty much pulled out of thin air.

Nothing new to see here: http://en.wikipedia.org/wiki/Dunbar%27s_Number

I suspect that you didn't read the article. In addition to heavily discussing Dunbar's number, the entire point of the article is that, even with the aid of social networking technology like Twitter, Dunbar's number still applies. From the article:

"The bottom line is this: social networking allows us to vastly increase the number of individual we can connect with. But it does nothing to change our capability to socialise. However hard we try, we cannot maintain close links with more than about 150 buddies."

So indeed, nothing new. They might have the same results if they used phone calls as well. I 'm not sure twitter is the right medium for such studies, though.

No no no no no. A thousand times no.

First of all, the monkeysphere does not work this way. The old cracked article (linked elsewhere but also provided here[1]) is sanctimonious overstatement. Not all friends are equal. We don't live in groups in the same way anymore. (Its most blatant stupidity is to claim that we have absolute no interest in strangers, but only slightly less grating is its ignorance of the 6-degree effects that keep us united as a species.)

All the monkeysphere can _safely_ say is that there is a limit to the number of connections you have; from an I/O perspective this is obvious.

But there's nothing special about the number 150 as it is an _average_. And TWITTER IS NOT REAL LIFE. Strictly speaking the damn article doesn't even get the terms right, you don't _have_ twitter friends, you follow people in order to build a stream of interesting things.

Why am I so angry? WHY AM I SO--uh, sorry.

I'm angry because this is the very worst of pop psych, the very worst of science writing. Someone took a sensible scientific concept--Dunbar's number--and starts applying it to everything in sight without regard to the scientific method.

Then someone else writes about it.

The valid science of the article, such as it is, is to show that online connections follow some similar patterns to offline connections, with variable levels of connectedness.

Also, I've got a knee-jerk visceral reaction to that cracked article and knew I'd see it here. In fact it'd probably be fair to say I'm ranting more against it than against the submission. Oh well, I still think I have a point.

--- oh yeah oops [1]http://www.cracked.com/article_14990_what-monkeysphere.html

curiously, dunbar talks about a bunch of different groups inside the "150" exactly as you say.

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