Received in an email from Michel

Online merchants such as Amazon, iTunes and Netflix may stock more items than your local book, CD, or video store, but they are no friend to "niche culture". Internet sharing mechanisms such as YouTube and Google PageRank, which distil the clicks of millions of people into recommendations, may also be promoting an online monoculture. Even word of mouth recommendations such as blogging links may exert a homogenizing pressure and lead to an online culture that is less democratic and less equitable, than offline culture.

Whenever I make these claims someone says "Well I use Netflix and it's shown me all kinds of films I didn't know about before. It's broadened my experience, so that's an increase in diversity." And someone else points to the latest viral home video on YouTube as evidence of niche success.

So this post explains why your gut feel is wrong.

The argument comes from a paper by Daniel M. Fleder and Kartik Hosanagar called Blockbuster Culture's Next Rise or Fall: The Impact of Recommender Systems on Sales Diversity. (http://papers.ssrn.com/sol3/papers.cfm?abstract_id=955984) They simulate a number of different kinds of recommender system and look at how these systems affect the diversity of a set of choices. Towards the end of the paper they observe that some of their recommender systems increase the experience of diversity for every individual in the sample and yet decrease the overall diversity of the culture. So I wrote a program that does basically what they do in their paper and tweaked it to highlight this result.

[...]

So there it is. Individual diversity and cultural homogeneity coexisting in what we might call monopoly populism.

But don't think this is just about automated recommender systems, like the ones that Amazon and Netflix use. The recommender "system" could be anything that tends to build on its own popularity, including word of mouth. A couple of weeks ago someone pointed me to this video of Madin, a six-year-old soccer prodigy from Algeria, and the next day my son, who moves in very different online circles to me, was watching the same one. I know who Jim Cramer is even though we don't get CNBC in Canada because everyone is talking about him and helping his disembodied head to shoot down Jon Stewart. More people watched Tina Fey being Sarah Palin online than on Saturday Night Live, and Fey is now famous in countries where no one watches the TV show. Clay Shirky writes an essay and I get five different links to it in my Google Reader feed in one morning. Our online experiences are heavily correlated, and we end up with monopoly populism.

A "niche", remember, is a protected and hidden recess or cranny, not just another row in a big database. Ecological niches need protection from the surrounding harsh environment if they are to thrive. Simply putting lots of music into a single online iTunes store is no recipe for a broad, niche-friendly culture.