Josh Porter makes a good observation: “a big difference between Facebook & Twitter is serendipity. Stuff “happens” all the time on Twitter. Not really so much on FB.” Twitter’s serendipity is an outcome of its design. Twitter asymmetrical, mostly-public, searchable network creates serendipity. Facebook’s mostly-private symmetrical network doesn’t.
Twitter generates serendipity with visible mentions and searches in your extended network. You can see replies from people you aren’t following. This allows you to expand your contacts and knowledge beyond people you already know. When someone asks an interesting question, you can do a search and watch the answers and responses unfold, bringing you to references and people you didn’t know before. By contrast, Facebook’s mostly-closed, symmetrical network makes it hard by design to see outside of your social network.
Handles and hashtags also help with serendipity. Handles are unique, so you can do a search for @bokardo and see the stream of references to Josh Porter, much more easily than if you searched for Josh Porter. This is a major advantage of Twitter over Facebook and LinkedIn, where searches for common names yield enough results that it’s nearly impossible to find a person with a common name. Hashtags make it easy to generate a topic by social convention and follow the thread. It is doubtful that Twitter intended handles to be useful for search and serendipity – they just used a convention that’s ubiquitous in consumer web services. Twitter doesn’t even have any explicit support for hashtags – they arose as social convention in the community. But as search became an integral part of the Twitter experience, handles and hashtags help.
My favorite thing about Twitter serendipity is that “pivot search” on people and tags kicks in when you get actively engaged in a topic. Most design patterns intended to support serendipity do a query for you, and deliver “recommended results” using some algorithm. An article about bank bailouts has several other suggested articles on the same topic. When you’re reading, you may or may not be reading more. Personally, I’m more likely to follow hand-picked links the author has chosen within the context of the article. The human mind is a better filter than the algorithm.
By contrast, when a person or topic is interesting in Twitter, you can easily pivot on the person or topic and explore. A twitter hashtag search is likely interesting — more interesting than generic tag searches — because a tag points to an active conversation created in a social context, rather than an abstract topic. When you get interested in something, you can easily pursue it and discover interesting results. This “pivot search” design pattern may be ideally suited for infovores like me, and too implicit for people with other styles, but I really love it. It would be interesting to find out how many others use Twitter for pivot searches in this way.
In sum, there are properties of Twitter’s design: asymmetrical, mostly-public, searchable, easy-pivot, that foster serendipity. Some of them were probably designed by Twitter designers on purpose, others may be sweet side effects. As part of the evolutionary experiment in social software, they provide great lessons to learn from.