Coming from a background in branding and marketing, I spend a great deal of my time confusing and conflating the concepts of “user experience” and “usability,” often to the dismay of my more learned colleagues. I probably deserve their contempt — what with my slander of their profession and coral polo shirt — but the physical violence is generally unwarranted.

I am regularly reminded of the importance and inherence of the user’s expectations — the consistency of experience and interactivity — and how it can and should manifest throughout thoughtful application design. Beyond those grand efforts of simplifying features and improving interface design, how can we best communicate that experience just around the bend? How can we best rely on expected interactions and, when it’s necessary, attach overt user cues to unexpected ones? And so the bruises multiply.

But I cut my teeth in the land of sizzle, where the unexpected made the user experience, and the most we needed audiences to “get it” was to laugh at the punchline (right before the logo appeared and right after the duck barked). And though brand experiences and application experiences serve different purposes, I wonder if brand experiences have taught us to expect something from applications — just as application experiences have taught us to expect usability from brands.

Perhaps we have begun to expect pleasant surprises — intermittent bits of entertainment to break the monotony — from even our “function-first” applications.

As UX geeks, we often explore playful design and clever interactions as a way of nudging behaviors and deepening engagement. Even dry content is moistened with a bit of rewarding animation or a vaguely human-like conversational tone (Skype thrives as much on charm as it does technology, and everybody loves a 404 error with a little sympathetic spunk.). Unique interaction metaphors further up the ante. Hell, I recently found myself playing with an iPhone app that does unit conversions. UNIT CONVERSIONS.

But I propose that we are entering a time when engaging user experiences (including RIAs and other interfaces) transcends playfulness and, in select-and-increasing instances, toward a series of deliberate pleasant surprises. These pleasant surprises — scraps of media, public recognition, spontaneous games — enhance engagement, encourage exploration and, when metered out in balance with critical functions, improve productivity. That they come in unanticipated forms and at unexpected times encourages users to spend more time at their workstations (or whatever task acts as the trigger), trying to “crack the code” or simply stumble upon the next payoff.

It’s slot machine psychology for the everyday, really: nobody complains when they’re blindsided by reward. Instead, they sit patiently, work diligently, and look forward to it.