Bruce Schneier (my favorite cryptanalyst) has a great post about the psychological bases and effects of group size on organizations:

Primatologist Robin Dunbar derived this number by comparing neocortex — the “thinking” part of the mammalian brain — volume with the size of primate social groups. By analyzing data from 38 primate genera and extrapolating to the human neocortex size, he predicted a human “mean group size” of roughly 150.

This number appears regularly in human society; it’s the estimated size of a Neolithic farming village, the size at which Hittite settlements split, and the basic unit in professional armies from Roman times to the present day. Larger group sizes aren’t as stable because their members don’t know each other well enough. Instead of thinking of the members as people, we think of them as groups of people. For such groups to function well, they need externally imposed structure, such as name badges.

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More generally, there are several layers of natural human group size that increase with a ratio of approximately three: 5, 15, 50, 150, 500, and 1500 — although, really, the numbers aren’t as precise as all that, and groups that are less focused on survival tend to be smaller. The layers relate to both the intensity and intimacy of relationship and the frequency of contact.

The smallest, three to five, is a “clique”: the number of people from whom you would seek help in times of severe emotional distress. The twelve to 20 group is the “sympathy group”: people with which you have special ties. After that, 30 to 50 is the typical size of hunter-gatherer overnight camps, generally drawn from the same pool of 150 people. No matter what size company you work for, there are only about 150 people you consider to be “co-workers.” (In small companies, Alice and Bob handle accounting. In larger companies, it’s the accounting department — and maybe you know someone there personally.) The 500-person group is the “megaband,” and the 1,500-person group is the “tribe.” Fifteen hundred is roughly the number of faces we can put names to, and the typical size of a hunter-gatherer society.

These numbers are reflected in military organization throughout history: squads of 10 to 15 organized into platoons of three to four squads, organized into companies of three to four platoons, organized into battalions of three to four companies, organized into regiments of three to four batallions, organized into divisions of two to three regiments, and organized into corps of two to three divisions.

Coherence can become a real problem once organizations get above about 150 in size. So as group sizes grow across these boundaries, they have more externally imposed infrastructure — and more formalized security systems. In intimate groups, pretty much all security is ad hoc. Companies smaller than 150 don’t bother with name badges; companies greater than 500 hire a guard to sit in the lobby and check badges. The military have had centuries of experience with this under rather trying circumstances, but even there the real commitment and bonding invariably occurs at the company level. Above that you need to have rank imposed by discipline.

Aside from being an interesting piece of neuro-psych trivia, this seems like something worth considering in the context of our discussions of shared space and community.  If an apartment complex with 300 people has no chance of developing a coherent community identity, how can we go about providing the structure to allow localized community identity to develop within portions of the complex?  What is a ‘good’ size for such a community?  It would seem that aside from the capacity of the brain to maintain relations with other individuals, other matters would come into play: having enough neighbors you can ignore the ones you don’t like, but not so many you never feel encouraged to speak to any of them, providing a good mix of privacy and shared space, etc.  It would be interesting to look into research along these lines, I’m sure it’s been done…

Google just released a service called Latitude, which enables people with certain types of cell phones to publish their physical location.  From Computerworld:

How does Latitude do that? Google is using technology that’s similar to that of Skyhook Wireless in its Latitude service. Like Skyhook, it is a software-only location solution that allows any mobile device with Wi-Fi, GPS or a cellular radio to determine its position with an accuracy of 10 to 20 meters. What sets XPS apart is that it uses land-based Wi-Fi access points, GPS satellites and cellular towers to determine location information.

In other words, Latitude can use any of the three kinds of signals — Wi-Fi, 2G/3G/4G mobile or GPS satellite — that a device can pick up to work out its location. By leveraging these wireless capabilities, the software can combine positioning data from satellites, carrier assistance servers and Wi-Fi base stations to significantly speed up positioning, or TTFF (time to first fix). TTFF for some devices can be up to a minute, but by using multiple reference sites, Latitude can reduce TTFF to a few seconds.

Basically, the software installs on your phone and  periodically checks to see where the phone is located, then send that information to Google.  Aside from the slightly creepy privacy implications, this seems like an interesting way for buildings to ‘know’ where their occupants are located (or their cellphones at least).

I could imagine houses closing the windows, turning off the lights, and dropping the temperature when nobody’s home, then reversing the cycle as the owner starts driving home from work.

I could also see some interesting urban dynamics research using this system if it were widely adopted and the data were public (again, my privacy nerve is twitching…)

Bruce Schneier just re-published a great essay on data and privacy worth a read.  Some excerpts:

Welcome to the future, where everything about you is saved. A future where your actions are recorded, your movements are tracked, and your conversations are no longer ephemeral. A future brought to you not by some 1984-like dystopia, but by the natural tendencies of computers to produce data.

Data is the pollution of the information age. It’s a natural byproduct of every computer-mediated interaction. It stays around forever, unless it’s disposed of. It is valuable when reused, but it must be done carefully. Otherwise, its after effects are toxic.

And just as 100 years ago people ignored pollution in our rush to build the Industrial Age, today we’re ignoring data in our rush to build the Information Age.

And all those cameras, now visible, will shrink to the point where you won’t even see them. Ephemeral conversation will all but disappear, and you’ll think it normal. Already your children live much more of their lives in public than you do. Your future has no privacy, not because of some police-state governmental tendencies or corporate malfeasance, but because computers naturally produce data.

While the privacy issue interests me, I think the large point here is that we’re creating a world with a much richer information landscape.  To date this information has been used mostly to either fight crime or hawk products.

The interaction of this information landscape and the physical landscape (ie architecture and urban planning) has not been investigated as much, aside from a few art projects with little impact on people’s daily lives.