The best interface to software might be doing nothing at all. Implicit interfaces are gaining mindshare. This is not a new idea. Amazon improves your experience based on your habits, for example. Google increasingly employs subtle, personal weighting of our search results. In The Implicit Web, Alex Iskold talks about the services of Amazon, Google, and Last.fm. All of them take advantage of the implicit actions of their users. Last.fm lets us track, publish, and find songs we listen to and like, and after installation, I forget it most of the time I use it.
A number of services have risen that really should be implicit, but are not. This might be caused by implicit interfaces' very nature of being unseen. Although they can be wonderful ways to interact with our networks, they are difficult to deploy. Developing the algorithms to translate user behavior into user interaction, without hindering the user experience, can be difficult. Even coming up with an idea for employing implicitness is difficult.
The ultimate implicit application might be Google, when taken in terms of number of users. Their intuitive Page Rank system turns millions of web pages interlinking between one another and turned it into a social ranking system. Digg, reddit, and their clones are hot news these days; however, we can't deny that they have done little more than turn what was implicit into something explicit. The change has good and bad qualities. An ironic note: Google seems completely unimpressed with social services, being the only major player expressing no interest in a service like social bookmarks. At least, this might appear to be the case, at first glance. However, when we take note that Google's entire business is built on the idea of utilizing the links on our web pages as votes, we find they were ahead of the game and have the largest social bookmarking site on the internet. The only missing features are associating the websites with actual people.
Why the Explicitness
If Google were so successful with the first massively deployed implicit interface, why would sites adapt the pattern into explicit voting systems? The migration from searching to sifting is a probable cause. The original Google model works great for mostly static content. Asking the popular search engine "What's new?" is not easy, and this is an angle explicit services employ. Social networks are nothing new, but the personal and explicit aspects are newly pushed. A search engine tells you which webpages are popular, but thinks knowing who agrees is less important. They also have a hard time distinguishing between things you like and things you do not like.
We need to evaluate what makes a good system, which explicit interfaces can become implicit, and what naturally implicit features to improve. Embracing the implicit areas leads to a higher level of user involvement, because they can be involved when they are unaware of it. However, making the user aware of the affects of their implicit interactions might be exactly the sort of thing the user needs to understand these services are actually there and valuable. There is little market for sites that asks you manually rank books and movies and recommend more to you. Amazon made its business on doing just that, because it takes information automatically and makes it obvious to the user what value they are getting. I routinely buy books from my Amazon page, because I know my habits are tuned it into a great place for me to find what I need. The implicit is there, but I explicitly take advantage of it.