I am a long-time LinkedIn user, and over time I've accumulated over1,000 connections. Most of them are people I actually know or at leasthave interacted with online beyond "connecting".

You might think that's a large number of people to have asconnections, and that I could afford to have a more selective velvetrope. And, as you may have noted, I know only most of my connections;some of them are link spammers whose connection requests I nonethelessaccepted.

But, you see, there's no incentive for an individual to reject aspammy connection request. Link spammers do reduce the relative valueof legitimate links, and as a result devalue the LinkedIn network as awhole. But it's a classic tragedy of the commons. Why should Ipersonally sacrifice the reach of my network if I gain nothing? As faras I can tell, this problem applies just as much to Facebook and othersocial networking platforms.

Twitter is a different beast. Granted, Twitter and LinkedIn may noteven see each other as competitors, but that is beside the point. Theyare competing for people's social networking cycles, and all of today'ssocial networking platforms / applications are surely keeping theiroptions open as to what positions they will ultimately stake out.

In any case, what most differentiates Twitter from LinkedIn is theirattention economics. On LinkedIn, you incur a benefit--at no apparentcost--from the size of your network, up to degree 3. In contrast, allthat matters in the Twitter "social graph" are your immediate links.You don't get any direct benefit from connections at distance greaterthan 1. Moreover, the connections are asymmetric, as are their costsand benefits. Following people is an investment of your attention,where the return is access to information (in a broad sense). Beingfollowed is an investment of their attention, and hence an opportunityto exert influence. The asymmetry of Twitter connections is mostevident for celebrity influencers, who have far more followers thanfollowees.

While Twitter, at least in my view, is a work in progress, I thinkthey have done well to align their model with attention scarcity. I'mmost keenly aware of this scarcity as I decide whom to follow.Accepting a connection from a LinkedIn spammer costs me nothing, whilefollowing someone on Twitter who updates on every inhale and exhalewould render the service completely worthless.

As a result, connections in Twitter reflect real value. Theycorrespond to investments of attention. Someone with many followers ismuch like an author with many readers. While I'm sure this metric canbe gamed (e.g., by creating bogus Twitter accounts and having themfollow you), at least Twitter has the model right in principle.

Speaking of which, if you're interested in following my tweets, you can find them here.

Note: this was originally posted at The Noisy Channel.