Intuitive UI: What the heck is it?

For any UX project, it’s almost a sure thing that a top goal is to have an “intuitive UI.” To users, describing a UI as intuitive is among the highest praise they can bestow. Given this, it’s reasonable to ask what it means for a UI to be intuitive. Surprisingly, nobody really knows. Ironically, people’s definition of intuitive is, well, intuitive, as they struggle to define the term in a specific, meaningful way. (Other popular UI goals share this problem, “simple,” “easy to use,” and “clean” being runners up.)

A practical question: How can you achieve a project goal if you don’t even know what it is?

My practical answer: You can’t. The term “intuitive” is meaningless as a UI characteristic, so—with the exception of casual conversation—we should avoid using it, at least without prior definition.

Struggling for a definition

I used to work at Microsoft and as a Microsoft employee, it wasn’t uncommon for people to tell me (with a certain glee) that, they, unfortunately, prefer using a Mac. While I primarily use PCs, I too have a Mac and have had a current model for decades. I like the Mac and appreciate its advantages (along with its disadvantages), but knowing that my lack of disapproval would be disappointing, I always keep that detail to myself. Everyone assumes Microsoft employees hate Macs.

From this point, the conversations have been remarkably consistent. My response: “Really, why is that?” To this their response is consistent and immediate: “I find the Mac much more intuitive.” My response: “Interesting—could you give me some specific examples of how it is more intuitive?” With this question, their glee turns to shock and horror as if to say “Of course, the Mac is more intuitive—how dare you question that!”  From this point, they would struggle to come up with some sort of answer, ranging from “it just is” to “it just works” to “it’s simpler” to “Mac apps have a more consistent look and feel.”

Sure, there’s an element of “intuitiveness” in those responses, but there is no clear, consistent definition. Sans the reality distortion field, in practice intuitive just means better. But going back to our UX project, imagine a project goal being a “better UI.”  An equally useless as a goal, just more obviously so.

A dictionary definition

Starting with the definition of intuition from Wikipedia, I’ll say that the “dictionary definition” of intuitive is:

A UI is intuitive when users understand its behavior and effect without use of reason, experimentation, assistance, or special training.

For such intuition to be possible requires prior knowledge, either from experience in the real world or with other software. So, for example, if something looks like a push button, we know from the real world that we can click on it to make something happen. Alternatively, if something looks like a link, we know we click on it from experience with other software.

We can boil this definition down to two requirements: affordance and consistency, where affordance allows us to predict what is going to happen based on appearance, and consistency to make that prediction correct. Labeling and context are also factors in making the prediction.

So is intuitive just a fancy word for affordance, consistency, and predictability? It could be, but when people use the term, I think they have more in mind.

Everett’s definition

I like to define things, so I’ll take a crack at it. A UI is intuitive when it has an appropriate combination of:

  • Affordance Visually, the UI has clues that indicate what it is going to do. Users don’t have to experiment or deduce the interaction. The affordances are based on real-world experiences or standard UI conventions.
  • Expectation Functionally, the UI delivers the expected, predictable results, with no surprises. Users don’t have to experiment or deduce the effect. The expectations are based on labels, real-world experiences, or standard UI conventions.
  • Efficiency The UI enables users to perform an action with a minimum amount of effort. If the intention is clear, the UI delivers the expected results the first time so that users don’t have to repeat the action (perhaps with variations) to get what they want.
  • Responsiveness The UI gives clear, immediate feedback to indicate that the action is happening, and was either successful or unsuccessful.
  • Forgiveness If users make a mistake, either the right thing happens anyway or they can fix or undo the action with ease.
  • Explorability Users can navigate throughout the UI without fear of penalty or unintended consequences, or of getting lost.
  • No frustration Emotionally, users are satisfied with the interaction.

Of these elements, the first two reflect the dictionary definition, and the others are those extra attributes that go beyond the literal definition.

Achieving your goals

If your goal is an “intuitive” UI, I think it’s best to explicitly spell out exactly what you want using the above attributes. Don’t use the term in specs, proposals, or plans unless you define the term in detail beforehand. When evaluating a UI, always do it in terms of the specifics. Otherwise, intuitive will end up being a vague synonym for good instead. That’s at best. The world’s most confusing UI could be credibly described by its creators as intuitive as long as the term isn’t defined specifically.

If you do only one thing:
Don’t use the term intuitive to describe a UI without a definition because nobody understands what it means. Instead, define the term specifically in your documents or describe your goals using more specific terms.

A footnote

I’ve got 80+ UI books in my library, but only two bothered to define the term. In The Humane Interface, Jef Raskin defines intuitive as familiar. I prefer consistent though because it is more specific and actionable. In Software for Use, Larry Constantine and Lucy Lockwood define it as guessable and behaving as expected.

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