Wednesday, June 08, 2005

On Dunbar's Number

I am way late reading onfac posts, so I hope duck-grinned Nancy won't mind if I comment on Dunbar number only now...

The author worked on animal and human groups and argues that, regardless of the habitat ecological specifics which determine group size, there exists a species-specific upper limit to such size beyond which groups loose cohesion and integrity. This constraint is said to be, by Dunbar, of neocortex origin.

This makes sense experientially, since everyone of us is familiar with the sensation of not "keeping up" with his/her address book when the number of contacts exceeds a threshold. It also makes sense scientifically, in that it's easy to understand how a the cortex is circuitry and, just like any circuit, it can go in overload when too many contacts are active in the same moment. More or less, like it happens in generalized epileptic crises, where in fact conscience is always lost.

There has been a lot of fuss, in a lot of articles and blogs, over this Dunbar number. My impression is, most people misunderstood (or stretched) what Dunbar wrote. Let's see why.

What Dunbar himself defined as social grooming, is an activity that Primates get engaged into for social purposes and the time spent in it correlates with group size. Men and women, though, do not engage in such cleaning activity litterally (with the exception of trying make-up and beauty masks on one another LOL).


What is really interesting in what Dunbar said is how the following statement managed to get overlooked:


"the relationship between group size and time devoted to grooming appears to be a consequence of the intensity with which a small number of key "friendships" (the primary network) is serviced rather than to the total number of individuals in the group."


which explains why so much bs on the size of online groups has been said.

Re-read the above quote and reinterpret it in light of online settings:

"the relationship between group size and time devoted to grooming appears to be a consequence of the intensity with which a small number of key "friendships" (the primary network - also known as 'close ties withing the group') is serviced rather than to the total number of individuals in the group - also known as group members."


Which means that the Dunban number applies to the number of close ties we can have in a group or, if you prefer, the number of nodes another node can be connected to (from a social network perspective).

In fact, Dunban adds:
"These primary networks function as coalitions whose primary purpose is to buffer their members against harassment by the other members of the group. The larger the group, the more harassment and stress an individual faces (see for example Dunbar 1988) and the more important those coalitions are. It seems that a coalition's effectiveness (in the sense of its members' willingness to come to each other's aid) is directly related to the amount of time its members spend grooming each other (see Cheney & Seyfarth 1984, Dunbar 1984). Hence, the larger the group, the more time individuals devote to grooming with the members of their coalitionary clique."

Dunban himself goes the extramile to define "natural conditions" under which studying Homo sapiens sapiens groupings, but in a technological world, with less physical cues, is such number the same? I mean, if we hypothesize, like Dunban did, that there is a threshold beyond which the neocortex gets too stimulated, how does this change in conditions in which the tie, virtual encounter, stimulation, is weaker because of the lesser amount of cues? It would make sense that we as humans would be able to tolerate a higher amount of online group members, vs F2F ones....

The trimodal distribution Dunban discovered (ie: bands 30-50, clans 100-200 and tribes 1000-2000) could still make sense in an online environment, but... for the same numbers?

What however does tickle our imagination is that the size of clans tend to varies very little, thereby making plausible Dunban's assumption for it to be a cognitive restraint. But again this might tell us how such restraint does apply to online clans as well, but it does NOT tell us that the number would be the same. Fact is, the kind of interaction is different and it makes sense the number be different as well.

Here Dunban helps us by writing (emphasis added):
"It is important to note that the intermediate level groupings do not always have an obvious physical manifestation. Whereas overnight camps can readily be identified as demographic units in time and space and the tribal groupings can be identified either by linguistic homogeneity or geographical location (and often both), the intermediate level groupings are often defined more in terms of ritual functions: they may gather together once a year to enact rituals of special significance to the group (such as initiation rites), but for much of the time the members can be dispersed over a wide geographical area and, in some cases, may even live with members of other clan groupings. Nonetheless, what seems to characterise this level of grouping is that it constitutes a subset of the population that interacts on a sufficiently regular basis to have strong bonds based on direct personal knowledge."

So, summing it up and translating it into our online life:

  1. the intermediate level groupings do not always have an obvious physical manifestation: this property is shared by online groups
  2. the intermediate level groupings are often defined more in terms of ritual functions: this property too can be shared by online groups, especially communities of practice
  3. for much of the time the members can be dispersed over a wide geographical area: this is shared by online groups as well
  4. it constitutes a subset of the population that interacts on a sufficiently regular basis: this is the definition of a social network

From all of this, we may reasonably think that it does exist a number beyond which our mind is constrained even in online settings. There are no reason, however, to think such number to be the same that applies to F2F interactions. There are reasons to think such number to be higher.

1 Comments:

Blogger Bill Harris said...

Thanks, Rosanna; I think I missed the original discussion in onlinefacilitation. I thought it was worth emphasizing, so I blogged about your entry, too.

5:57 am  

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