Designers love diagrams. We tend to be visual thinkers. Where verbal thinkers feel they understand things when they find the right words to express a thought, designers feel they understand when they find the right shape. And so, it is unsurprising that designers understand their work in diagrams.
If you ask a designer what they do, there’s a strong chance they’ll draw a Venn diagram. There is an equally strong chance one of the three overlapping circles will be labeled “desirable.”
Perhaps the most popular one is the desirability-viability-feasibility triad. My first exposure to it was in the late 90s, but it was expressed in different terms. A User Experience Architect used it to explain to me that our role was responsible for finding the overlap between:
- User (what users want and need; later called “desirability”)
- Technology (what engineers can do; later called “feasibility”)
- Business (what serves business goals; later called “viability”)
According to one source, it was IDEO that developed and popularized the now ubiquitous desirability-viability-feasibility model. What is desirable, viable, and feasible satisfies the needs of people, is good for the business, and can be developed and delivered easily enough that it is worthwhile.
Another version, which I believe predates the other by almost a decade, is the usefulness-usability-desirability triad. When designers focus on the benefits they provide to people—and this is our primary focus—we often speak of these benefits in terms of good experience. This triad clarifies what is meant by “good experience.”
A good experience has three qualities, which are:
- Usefulness (the design satisfies functional needs)
- Usability (the design minimizes functional obstacles)
- Desirability (the design is valuable beyond its function)
Years ago, I became curious about where this triad originated. It turns out it was conceived in 1992 by Liz Sanders, who is now known primarily for her work in participatory design. To the degree a design affords usefulness, usability, and desirability, it will be valued by people and adopted.
So, which of these two Venn diagrams is preferable? They seem to do similar things with a similar shape and with one overlapping word. Do we just choose the one we like better? Do we just choose the one that we think will resonate more with our audience?
I propose that these two triads complement each other. This becomes easier to see if we avoid using the word “desirability” in two different ways. In the desirability-viability-feasibility triad, desirability is about people’s response to what is being designed. It asks if the design will actually be adopted. Let’s call it “adoptability”.
Adoptability is the goal of a good experience. Looking at the usefulness-usability-desirability triad, they define what is adoptable. So the usefulness-usability-desirability triad fits inside the adoptability region of our new adoptability-viability-feasibility triad.
To summarize,
- The Venn diagrams designers use to explain design complement each other and give a more complete picture of what we do.
- It is not only okay but admirable to get excited about Venn diagrams.
- The only thing more exciting than a Venn diagram is a Venn diagram inside another Venn diagram.
