In a nutshell, the principle is this: where Usability removes friction from an experience (thus making it easier to accomplish), Motivation (aka a Compelling Experience) will increase the user's desire to go through the experience. Anderson has a handy reference picture of this:
|Usability removes friction from an experience, Motivation increases the user's desire to go through the experience. "Paraphrased" from Joshua Porter's original work|
I think one of the reasons Anderson's work struck such a chord with me (besides the fact that, let's admit it, he's a FANTASTIC speaker) is because he's marrying many fields of research and work, and distilling it all down to the principles most relevant to design. That feels right to me, not only because I share his broad interests, but also because many of the great insights and discoveries in history have been made by people who refused to see the world in only one way. They sought out information on "unrelated" interests. And then... one day in the bathtub... BAM!! It all comes together!
Anderson has done the leg-work to assimilate information from fields as disparate as economics, game theory, and neuroscience. He has recently distilled this information in the form of a series of cards, similar to the IDEO Method cards, which he calls Mental Notes.
Each card lists a principle of psychology, a description of how that principle drives each of us, and gives some ideas on how we (the designers) might use this principle in our work to make our experiences more compelling. And the illustrations are a hoot; every time I flip through the cards, I find something that makes me laugh out loud!
Anderson is no slouch when it comes to walking the walk, either. He has clearly used his own principles in the construction of this deck: The box it comes in is beautiful (Aesthetic-Usability Effect), the cards are succinct (Curiosity, Need for Certainty), funny (Humor Effect, Peak-End Rule), and references to the original psychological principle names lends them weight (Authority). And the illustrations by Kevin Cornell are both funny and really help us quickly understand the concepts (Conceptual Metaphor, Visual Imagery). Full disclosure: Anderson probably has no idea who I am (except maybe that annoying girl in the third row with all the questions), and has not asked for any kind of endorsement. I'm just an avid supporter of his work!
One of the reasons I think all of this is so important is that it's a perfect suppliment to usability. Take another look at the picture above. In a perfect world, designers would be able to take that hump down to zero, making a perfectly smooth, flat, frictionless surface. Now come back to the real world. There will always be applications with learning curves, things which require us to understand before we proceed. Every question we ask our users increases the size of this little hill. But without asking questions, we can never learn, we can never make the system do what THEY want it to do (as opposed to what we would have chosen for them).
This is where motivation comes in. If we can make the experience compelling, make the user WANT to go through what we're about to put them through, we and they will be better off for it. Think about it like the recent changes in dentist's offices: HD TVs, headphones, clean-while-you-sleep procedures... all designed to make the experience more enjoyable, less of a chore. Dentists are hoping that if patients actually ENJOY their check-ups more, we might show up more often. And I think there's something to that. Now if only they would hand out gamer points for scheduling my appointments on time...