Core Design Principles

1. Profound Simplicity – apps should be clear and concise in delivering information. It should maximize accessibility with minimized complexity.
2. Feedback – status, warnings, errors, and different actions should be effectively communicated while the app is running. These queues should be discrete and obvious in conveying what they mean.
3. Visibility – this greatly improves usability by clearly displaying key information. It directly tells users what they need to know based on what is presented to them.
4. Consistency – understand the expectations people have for your app. Use icons and features that others are most familiar with to make the experience more intuitive.
5. Mental Models – systems which meet our understanding and expectations on how they operate feel more natural and intuitive. Trying to be innovative could potentially break mental models on how something should function, decreasing usability of the app.
6. Proximity – the closer the control is to an object, the more it gets associated with that object. For example, a switch in the bathroom ought to control things in the bathroom and not the living room.
7. Grouping – helps to understand relationship between multiple elements. Groups make it easy to associate related controls together and improve navigation.
8. Mapping – control systems should mirror their functionality. This factors into peoples’ mental models of how things ought to work.
9. Affordance – the design of something reflects the uses someone would have for it. This can be largely subjective, but people inevitably assign meaning to tools and interpret how they should be used.
10. Progressive Disclosure – simple and relevant information is presented up front, while more complex features are not as forwardly presented. This goes hand-in-hand with the 80/20 rule – 20% of the actions should cover 80% of the benefits of that app.
11. Symmetry – these types of designs are associated with balance and orderliness so it naturally reflects strong design. In addition to being aesthetically pleasing, symmetry also provides an intuitive flow to an app’s overall layout.

An app that I use just about every day is my guitar tuning app. It’s really important for me to tune my instrument before playing for the best experience, so a free app which ensures that was just what I needed. Guitar Tuna (as it is called) definitely embodies the profound simplicity necessary for mobile app design. Upon launching the app it immediately takes you to the tuner view and doesn’t bombard you with options and preferences. By default it is set to standard tuning, since that’s the most common, but others can be selected as well. There are other features like a metronome, some basic lessons, and even a chord library to reference, however, these are not forced on the user in any way; the purpose of the app is to tune a guitar and its profound simplicity makes it easily accessible to the average user.

Occasionally, I get the urge to study a new language on my phone. There are dozens of language apps, but the one I use most often is Lingo Deer. This app is very well designed and has a lot of tools for studying language. The app’s main page is comprised of 50+ sections each with 2-4 lessons. Right off the bat, Lingo Deer makes good use of grouping and symmetry to organize the library of linguistic lessons available to the user. All of the sections are displayed on the home page in two linear columns, becoming more challenging as you progress. Because I’m learning Japanese, it naturally started me off with learning the alphabet and basic phrases, but the grammar and vocabulary has become gradually more complex. At first the base lessons were all I used, although the app has more to offer in statistics, challenges, and various review games. This is an example of progressive disclosure — I could’ve been satisfied going through the preset curriculum, but the app has a lot more to offer and is only one or two taps away. Designing it in this way makes it that much more accessible, because 80% of what I use the app for (grammar and vocab lessons) is contained in just one section of the app, but there’s still a lot more to be gained from it that isn’t as apparent to first time users.