Twitter and the Dunbar Number

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I’ve never been in the camp of those who follow back every one who adds them on social networks. While the reason people reciprocate all follows-it does seem the polite thing to do-is understandable, I know I’ll never be able to have any kind of meaningful interaction with all of them (over 6,000 now on Twitter). So to me, it seems the more courteous thing to do is not to follow everyone back, but to make sure I respond to anyone who sends an @ message to me.

My question in this blog post is to ask how you determine your “friending” policy on social networks, especially Twitter.

Yesterday I started a TwtPoll to ask the question. Of course, this is not a scientific survey, and is only a small sample of people-83 people who follow me on Twitter or who follow someone who kindly retweeted the poll for me. And the number 1,000 is an arbitrary threshold.

The results, frankly, surprised me a bit. I thought there might be more who valued reciprocity so highly they would unfollow someone who doesn’t follow them back. That is certainly the gambit of those trying to amass followers as quickly as possible, since Twitter seems to limit a person to following 2,000 people or 110 percent of those who follow them, whichever is higher.

But the vast majority of respondents indicated that it either didn’t matter whether I follow them back (46%) or that it was fine as long as I made an effort to respond to messages directed to me (42%). As Dave Shaw said, “Following is the ultimate opt-in and doesn’t require a follow back. Nice but not required. Responding to @’s and DM’s is just good manners.” (Please click through to the poll to read all the comments.)

As a result of the poll, I will be trimming back the number of people I follow on Twitter. If I can’t remember having any exchanges with someone, I’ll drop that person. Why? Because I’m following over 1,200 people but only paying attention to a few hundred at most.

And that meshes with the well-known Dunbar number, an estimation of the number of people with which one can realistically maintain relationships. For “real-life” friends, the average number is 150, with some people able to keep track of around 300.

I share Ross Mayfield’s view that social software allows us to augment the Dunbar number, which he based on the size of the neocortex in primates and then extrapolated to humans. Ross cites recent research that shows:

Twitter users have a very small number of friends compared to the number of followers and followees they declare. This implies the existence of two different networks: a very dense one made up of followers and followees, and a sparser and simpler network of actual friends. The latter proves to be a more influential network in driving Twitter usage.

That describes my experience. When I was using Twitter exclusively on the Web, I was easily following 500 people. Using tools like Twhirl and TweetDeck, I began to follow more people. TweetDeck gives the illusion of following 1,200+ people. But in reality, I ignore most of them. As the research shows, I have a group of “top friends” I keep in contact with by using the Group feature in TweetDeck. And the rest I try to read now and then-but that turns out to be so infrequently that those other people might as well not be on my “following” list.

David Armano and Russ Unger, Flickr photo by Matt Dickman
This topic has been on my mind since attending a salon discussion at South by Southwest Interactive led by David Armano and Russ Unger. Summarizing his thoughts about the Friendship Is Dead conversation and the concept of ambient intimacy on his Logic + Emotion blog, David concluded:

Most of us intuitively know who our friends are. … But, with networks we have access to more individuals then ever before in history. We know when they are sick, when they are traveling and even when they’ve lost a loved one. Some of us stay in constant communication with people who would have normally been considered “loose ties”, people we’ve met at an event, a party, a former co-worker, or college friend. These ties can become strengthened and feel like something more than they used to be.

What are your thoughts on the relevance of the Dunbar number to social networks and the proper etiquette for following people on Twitter?

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This post was written by:

Connie Reece - who has written 152 posts on Every Dot Connects.

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20 Comments For This Post

  1. Michelle / chelpixie Says:

    Thank you for sharing the results of that poll. It gives me something to think about as my Tweetdeck setup is currently like yours.

    I’m also surprised by the overwhelming response but I think it’s a healthy expectation.

  2. Mary Says:

    Hi Connie:
    This is a really interesting and thought provoking post. Thanks for putting it together and sharing it. Since joining Twitter I have tended to be very picky about who I follow. I use it to learn new things, to be intellectually stimulated and to be amused. Have a great day.

  3. BarbaraKB Says:

    Connie, great survey & post… thanks! Many of us use Twitter as individuals and not as a business alone (my *niece* just followed me yeasterda) thus our reasons for following: we actually *read* our tweet stream. I actually advocate follow all for a business only account. And I believe whoever you follow comes down to one word: value. I have blogger friends who are terrible in Twitter, so I read blog but not follow on Twitter. Some are great @ Twitter but not good bloggers. My 900 “friends” on Twitter is best for me. Again, I have honed that list for two years & value all. Last time I looked (check about once/month) 60 folks not follow me back. But I value their tweets so I continue to follow them. Finally, so many ways to use Twitter but biggest piece of advice: build your own follow list & live in peace w/your decision. Peace!


    Excellent answer, as I would expect from you, Barbara. I agree that we have to each set our own parameters for Twitter and be comfortable with that. I tweet primarily for business reasons, and yet have become personal friends with quite a few people on my list. In a workshop today, I did recommend one of the attendees follow back almost everyone (excluding the obvious spammers and MLMers) because she is tweeting to build a community. We looked at some of the tools she can use to follow conversations and try to scale them. Thanks for commenting. — Connie

  4. Concetta Says:

    Connie, great job in thinking this out with your survey and post. I agree entirely with the Dunbar number - I’m at a little over 200 followers and am following slightly more than that at 250-ish. I think if I tried to intelligently follow more, I’d go crazy. I’d have to really target them closely in order to interact.


    Concetta, do you try to read all the tweets from everyone you follow, or just jump in and read when you have time? When I was new to Twitter, I tried to read everything, and it soon drove me crazy! Twitter is the kind of thing you really can just drop in for a short visit, read and while, and then leave — knowing you’ll be back soon. — Connie

  5. Chris Collins Says:

    Hi Connie,

    I think you have a very unique style and attitude, that caters well to your followers. You’re one of my favorite people to follow on Twitter because you do take the time to reply to people. Many, of course, don’t.

    I know you were just trying to get a feel for how people would respond, and that you already understand the poll is unscientific. One thing it doesn’t take into account, is the people who are just not as active/social/extroverted, as the ones who would be likely to respond to a poll such as this. I could refer to Forrester’s Social Technographics chart. But you’ve seen it. And you know what I’m saying.

    I agree with you and Mayfield regarding the Dunbar numbers, and the idea that technology can help us augment our limitations as animals.

    The other thing we can’t forget though, is the psychological effects of belonging to a group, and reciprocity. Both of which are good in business, as in life. And while I can only speak for myself, I’m sure there are others like me, who take it as a sign of acknowledgment when someone decides to follow you back.

    Those of us who use Twitter, both personally and professionally, seek value from our followers. But Twitter is not yet an “efficient” communication aggregation and organization tool. And if you can’t keep up with that many people due to time or tool constraints, I think most people can accept that.

    What ends up happening however, when you don’t follow people back, is that you miss out on some tangential, yet valuable conversations, risk alienating people on first impression, and completely eliminate an entire back channel of communication: Direct Messages.

    I do not advocate following EVERYONE back. Just those who appear to be real people (not spammers), who are really interested in you, and who you think might be able to offer some relationship value in the future. As filtering and grouping features improve, I think the follow back question will become less of an issue.

    Anyway, I’m off my high horse. Thank you for bringing this up Connie, because I’m sure it will continue to be a strong point of discussion as time management and network scalability, become issues for more people.



    Chris, first of all, thank you so much for the compliment. I do try to respond to everyone who sends an @ message. It results in my being very chatty, and I even warn newcomers that they may not want to follow me because I will overwhelm their Twitter stream unless they are following quite a few people.

    You touched on what is the sticking point for me, and that is cutting off potential conversation with new people that I might thoroughly enjoy getting to know. On the one hand, if I don’t follow back most of the people who follow me, it can be perceived as an insult to them-that they are not worth my time. On the other hand, if I follow them back and just dump them in the “All Friends” column of my TweetDeck, I am in effect ignoring them. I use TweetDeck’s Group feature to keep track of the people I have the closest relationship to on Twitter. For time considerations, of course, I wind up reading all of the inner circle group’s tweets while never looking at the others.

    Thanks for adding to the discussion here. You raise some good points. -Connie

  6. Ike Says:

    This debate will never be settled. New waves of users come in with their own expectations.

    My guess is that most of the aggrieved are “friend collectors” who are spending too much time with an eye on their Follower count and not enough time being human beings.

    It was this gap in expectations that prompted me to write my Twitter policy ( ).

    I do have to agree with Chris that there are some people I leave open simply for Direct Messages, but it’s time to cull the list. Engagement trumps gesture.


    Ike, I went searching Occam’s Razor late last night while working on this post because I seemed to remember you writing a post about social media consultants needing to read Twitter on the Web, the way most users do, and to be able to teach people to use Twitter in that way. If that was your post, I didn’t find it. (And if so, please let me know so I can link to it.)

    I spent quite a bit of time this week reading Twitter on the Web, the old-fashioned way. I actually prefer that. When I started Twitter over two years ago, my brain learned to read in reverse chronological order and it stuck.

    What that did, of course, was force me to scan tweets from those newer followers not in my “inner circle,” and I found myself engaging some of them in conversation. The problem, as you mention, is that it just doesn’t scale. And as usual, you have summed it up succinctly: “engagement trumps gesture.” That’s the position I’ve adopted.-Connie

  7. Darin R. McClure Says:

    It is all about static to noise ratio, if the new follower is nothing but autoposts, then they really are not part of the conversation.

  8. Lisa McClure Says:

    The race for the friend count has alway eluded me. I follow people primarily because their updates either keep me informed, enlightened or entertained.

    Informed: Some Twitter folk are just really plugged in people by nature and I look for those who are discussing timely news and information. I try to find people who are like minded. for example is a site with great ideas and cutting edge topics and I use that as a filter to find interesting peeps.

    Enlightened: Different from informed in that Twitter helps me find things I didn’t even know to look for. I follow some people because the depth and variety of their tweets promises that I could discover something new.

    There are some Twitter folk who are just really funny or witty. I love how the limitation of 140 characters really taps into the wordsmiths out there. But then again I love haikus.

    I also agree that the Dunbar number could rise or fall with the use of tools. Maybe it should be the Dunbar Quotient and your tools are the lever to raise your listen/response quotient and ultimately the measure of value in information, enlightenment, and entertainment.

    Thanks for the thought provoking post Connie.


    I like the way you’ve spelled out your reasons for following people, Lisa. In my workshops I say that people should come up with a follower/friend policy from the beginning when they join a social network-I’ll include yours as an example (with attribution) because it’s well thought out.

    Intriguing idea about a Dunbar Quotient. I’d love to see an analytics guru tackle that. (I’m a wordsmith, not a numbers girl.) Thanks for carrying the conversation forward. -Connie

  9. Michael Sommermeyer Says:

    I have used @wordymouth as a way to connect with people I’ve met, but I must confess I use it mostly for learning new things. It’s sort of like standing at the beach and watching the waves bring in the interesting shells, rocks and bits of glass.

    I have met a ton of people through @wordymouth and I have tried to reply and answer questions that have come into me. I think answering a DM or a Reply is much more important than worrying about whether someone is following me back. A lot of folks I follow never follow me back and never reply to a message. I just figure I’m part of their noise or they are much more important than me. ;-) Those people who have replied back have become good friends. The rest I just toss back into the waves.

    Recently I created @msmrmyr because I found that a lot of the messages left by my friends have been getting lost. So I’m now following just those folks I really know or think I know. It’s a much smaller group.

    That doesn’t mean I don’t still value @wordymouth because I learn a lot from the folks I follow there and I talk to a lot of them.

    I think it can be summarized this way: we all have that one friend we’ve known since grade school and then there are all those folks we count as acquaintances. Sometimes those acquaintances become real friends. Maybe I’ll convert a few acquaintances into friends and for me the prospect of that happening is worth maintaining a large number of followers on @wordymouth.


    Great addition to the conversation, Michael. You’re on that list of people I follow on Twitter that I hope to meet in person some day.

    A couple of months ago I did a manual tabulation — went back and looked at the first 400 people I followed on Twitter that I was still following. Of that group I’ve so far met 125 of them. This notion of anonymous people hiding behind their computers in isolation is, for the most part, a myth. Social networks can be a tremendous boon to face-to-face networking. -Connie

  10. Millie M. Says:

    Everybody that follows me I follow back. There are a bunch of people that I follow that don’t follow me! I don’t really care whatever floats their boat. There are people that I would never come in contact with in real life because our circles are so different but that doesn’t mean I’m not facinated by them and not interested in what is going on in their lives!

    People are God’s greatest invention and I’m in awe of them! Social Networks like Twitter give me the opportunity to mingle from the safety of my own home. I think it is totally cool!

    I love diversity and I can get that on Twitter!

    This is a very interesting Blog by the way!

    Make This Day Your Best One Yet!

  11. Gavin Heaton Says:

    I am not all that convinced of the legitimacy of Dunbar’s Number.

    If I was to add together the number of people with whom I have significant relationships with - both on and offline - it would well exceed this.

    I also think that Ross Mayfield is on the right track, but don’t necessarily agree that social software augments our base 150 relationships, allowing us to re-cache our relationships dependent upon need. My view is that social technology does, in fact, extend the Dunbar Number - doing so by expanding our experience of dealing with the emotional impacts of larger numbers of people.

    In a way, this is what celebrities do - and it is why they cope so well with Twitter. So, I guess, with social software we are all z-list celebs now with our small coterie of friends, fans and foes.


    Gavin, I think some professionals-sales people, for example-are adept at keeping track of a lot more people than the average person. Is that ability a result of being in sales, or was that ability one of the reasons he or she wound up in sales? My dad had an amazing capacity to remember people across various walks of life and in many different locations. Wherever we traveled, someone would recognize him and start a conversation. What he did from memory, I rely on social computing to help me accomplish. And like you (if I understand your point correctly), I don’t really make distinctions between online and offline friends. I just happen to see my offline friends in person more often, but may have more frequent contact with online friends. Thanks for weighing in here.-Connie

  12. Nairobian Perspective Says:

    your post is quite true, ive been on twitter for quite a while but never took an interest in following back guys, but that changed drastically in the last few months, twitter traffic to my blog has subsequently increased, thanks for the article!

  13. Thibaut Thomas Says:

    Please stop using Dunbar’s number without reading his article first : he was talking about grooming among primates ! Mr Armano’s post is more subtle in its use of the so-called number, but if you can’t read french on my blog, where I use the second most-used-without-reading theory, the “Weak ties theory” to temper the Dunbar’s number, you should absolutely read Ms danah boyd PHD perfect explanation there :

    “This “Dunbar number” never referred to how many people you could possibly know, but how many people you could actively “groom.” Your contacts on Facebook are not equivalent to the people you groom. These can contain close and dear friends, but it can also be used as a rolodex for ties you don’t actively maintain.”


    In a blog post of 700 words it’s not possible to include every morsel of research I accumulated in writing. I’m well aware that Robin Dunbar’s original thesis referred to primate grooming and extrapolations to human behavior. And I agree with what Danah Boyd says in the quote above-one of my points in writing this post is that I do not subscribe to the notion of following all contacts on Twitter precisely because there is no possible way to cultivate relationships, i.e. “groom,” that many people.

    However, while only a portion of my Facebook and Twitter contacts are “equivalent to the people you groom,” in Dr. Boyd’s words, that number far exceeds 150. I do consider my interactions with certain friends on these networks “grooming,” in exactly the same way I “groom” friends at work, at church or in other groups I belong to. I have invested a considerable amount of time and emotion in cultivating friendships online and offline.-Connie

  14. Larry Robiner Says:

    I follow people on Twitter who I think have something interesting to say. I have no expectation that they will follow me back. That is the difference between a Twitter connection, which can be one-way, and a Facebook connection, which is two-way. Both types of connections have their place.

    If you follow me on Twitter, I assume you think I have something interesting to say. I will look at your profile and follow you back IF:
    1) I know you personally, or
    2) Your profile has a real name and location and bio that makes you seem like a real person who is not trying to sell me something, and a healthy percentage of your recent tweets are relevant, interesting, funny or otherwise compelling. If you are all about lunch, weather and TV, I’m not interested.

    There is no expectation on Twitter that followers will read EVERYTHING you tweet. That means that the number of Twitter connections can exceed the Dunbar number. Technology allows us to have more connections online than our feeble brains can manage at one time, simply because we don’t have to manage them all at one time, and we can use the tools to refresh our memory about prior interactions.

    I find that as I age, my personal Dunbar number goes down (what was your name, again?), but my life experience adds to the number of people I want to maintain connections with in my social network. I am thankful that we now have tools to pick up where my middle-aged memory leaves off.


    Larry, I hear you about middle-aged memory having an impact on your personal Dunbar number! I have a slightly different view of Twitter, perhaps because I’ve been on it so long-back when it was small enough that it was very much a two-way communication channel. It has changed dramatically as the network has grown exponentially over the past year. I still enjoy using it for two-way conversations, which is one of my reasons for hesitating to follow back so many people.-Connie

  15. Shireen Smtih Says:

    I have read this post and the comments with great interest, at a time when I should be doing something else. Having read this discussion, I just hope developments in the technology will make it easier to decide what to do. The main take away message for me out of all this, is that I must set myself up with Tweetdeck.


    Shireen, the tools you use for Twitter do have a bearing on your depth of interaction with people. TweetDeck has worked really well for me. I’ve also heard from fans of TweetGrid, which has many of the same features but works completely within your Web browser, while TweetDeck requires the installation of Adobe Air. (a quick free install)-Connie

  16. Ike Says:

    Connie, you weren’t imagining things.

    I’ve made a deliberate attempt to NOT make Occam’s RazR the 425th-ranked PR/Social Media blog. I’d like to think I have a different niche, and big prizes to whoever figures out what it is and how to articulate it.

    The piece I wrote is over at Media Bullseye:

    I’ve found that keeping my Twitter/SocMed pieces in a place where people are looking for it is more sustainable and less maddening to my readers who don’t care about the inside baseball. Likewise, I have an external outlet for my more staunchly libertarian thoughts and musings, so as not to alienate others.

    Gavin —

    I have no doubt that you have a real connection to more people than is typically quoted in the Dunbar number. But are all of those relationships “active” or are some in suspended animation.

    Example: I get along GREAT with Lee Hopkins. We’re Skyped and chatted and have a history of touting each others’ work. But Lee has been off my back-burner for over a year now. Nothing personal, no falling out, we just both got very busy on other projects and don’t have a “current” relationship.

    Now, he and I still “follow” each other, and when we do reconnect I have no doubt that we’ll pick up again just fine. There are many others I could name (but won’t because they don’t have skins as thick as Lee!)

    My point is that if you are carrying a larger number of people who you have a relationship with, you can’t sustain them with equal degree, not simultaneously.

    And there are people who are savants, and can juggle a far higher number. Technology allows for this, as Facebook nudges you when your friends have birthdays, giving you a reminder to re-engage. You may well be one of those with a higher tolerance, but I have to believe that most of us can’t concentrate on building out in that many directions at once — not without putting some “on ice.”


    Whew! My memory didn’t fail me-right author, wrong URL. Thanks for the link to your Media Bullseye piece; evidently I failed to bookmark it.

    Re: your example w/ Lee Hopkins. I do the same with offline friends as well. We get busy, or they move out of town, and we’re not in touch as much. But when we do have a chance to see each other, it’s easy to pick up the relationship quickly. To me the difference is not online/offline, but how many relationships we can hope to maintain in total. It may not be the Dunbar number, but it’s *some* number; and while it probably differs from individual to individual, it’s going to be within a certain range. — Connie

  17. Gavin Heaton Says:

    Ike + Connie … excellent discussion. I have been rethinking some of this for a while now.

    Perhaps the area that interests me most is the way that ambient intimacy and personal investment in a relationship overlaps. For example, even though I have not seen Drew McLellan for some time - not spoken, skyped, emailed or corresponded - it doesn’t mean that he has not been in my thoughts regularly. The closes I come is to read his blog or see his messages on Twitter. In many ways, this lack of interaction serves to reinforce the strength of my desire for that relationship. However, it does not lessen the importance of the friendship - and afterall, there is a difference between “growing” relationships and “being in” relationships - which also signify differing levels of maturity and engagement.

    Along with the way that we communicate, I have a feeling that technology is also transforming the very nature of relationships. And while, yes, there certainly is a limit somewhere, I think it may be more culturally, experientially and technologically determined than Dunbar allows. Think I may need to blog about this to be clearer ;)

    Gavin, I look forward to that blog post! It’s been a good discussion here. — Connie

  18. Ari Herzog Says:

    I’m betting if you scan the names of the 1000+ folks you follow on Twitter, you’ll instantly identify-without seeing their bios or recent tweets-if they are common twitterers with you. If you don’t recognize their names, unfollow. Further, if you initially followed them for X purpose and your behaviors and passions moved to Y, unfollow.

    You can always refollow.

  19. Russ Somers Says:

    Great post, Connie. If one thinks of Dunbar’s Number the way Dunbar did - as a function of neocortex size - it’s a hard-wired limit like the clock speed on a CPU. But one can still make the most of it by using technology (tools like Tweetdeck), strategy (making sure you have the *right* 150 people in the Dunbar Posse), and deliberate practice (many of the old-school techniques practices by ace networkers).

    I’m firmly in the ‘whatever works for them’ camp. I follow most people back because I find most people’s tweet streams interesting (shameless self-promoters excepted). I then have a small group of people who I make sure to read regularly and a much larger group of ‘everybody else’. I treat that larger group as ambient text radio, letting it scroll by without letting it create a feeling of obligation. Once a week I move folks in & out of the smaller group, based solely on what I’ve found interesting during the week.

    I do feel obligation to DMs and @ replies. I’ve made the mistake of not responding to those a time or two, but as I’ve experienced that myself I’ve come to feel that it’s rude. But others may not feel the same, especially those with much larger followings.

  20. Ed Says:

    Unless your a business with staff answering every dm well, (and nuking the spam all day), I agree with @Ed_Dale here:

    @ChrisBrogan is the only person I’ve witnessed do a great job with massive numbers followed (@Problogger does well too), but it is not sustainable.

    Moreover, autofollowing en masse, without background checking all,
    means you’ve helped spammers hide from Twitter Security.

    Take the time to read @’s. If a convo should result, it will.

    Thanks to @ConversationAge for the link here. Great discussion! :)

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