I tried out Simplenote on my iPhone for the first time the other day and was pleasantly surprised by the speed and, well, simplicity of the app over the slightly more bloated Evernote.

The UI in particular was pretty light and did a good job of staying out of your way. While on a note-taking binge, I also came across this little goodie.

Bear with me.

It surprised me to see tags being managed in this fashion – a clean and concise list of topics versus the typical endless mass of comma-delineated buzzwords. This is a perfect example of how an interface can guide user behaviour.

Compare this to Delicious:

Or Things:

Or even Simplenote’s web app:

These interfaces encourage a different kind of behaviour. Open and free-form input fields almost push you to keep typing tags until your fingers bleed. You tend to stop only when you can’t think of any more topical words to add.

But with Simplenote’s iPhone app, the interface requires you to hit the + icon, then type in the name of a single tag, then hit Done. This workflow discourages you from entering tag after tag and forces you to critically assess how many you’ll use. Whether Simplenote made a conscious choice to do this, or it’s just the result of standardized iOS UI (likely the latter), the point remains the same: the interface makes you self-moderate your own tagging behaviour. Beautiful.

Consider other ways an interface can impact how a user behaves:

  • Font size: the size of the text inside a field will impact how much a user wants to write. The larger the text, the less likely the user will want to write an essay in the field.
  • Field size: the size of a field suggests how it should be filled out. A single-line input box will encourage short singular statements, while a 3-line textarea box may encourage multi-line paragraphs.

On your next design project, consider what behaviours you want to encourage and which ones you want to discourage. Chances are, you can affect change simply by the way you design your interface. You can bet that a handful of these mechanisms will be in play in Rocketr when it launches.