Don Norman begins The Design of Everyday Things with an anecdote about doors. Not long ago, I was introduced to him and ‘Norman doors’ in this piece by 99% Invisible’s Roman Mars and Vox’s Joe Posner. The confusing interactions these doors signaled were immediately recognizable. The first chapter of Norman’s book goes on to outline an important distinction, one that separates aesthetics from good design. In describing his friends experience with a particularly difficult to use series of doors, he mentions that they were attractive, stylish, and “probably won a design prize”. What was clearly lacking was the consideration of how people would interact with them. Even though the doors may have been aesthetically pleasing, they lacked the two most important characteristics of good design; discoverability and understanding. 

A closer look at the devices around us reveals that many of them are over complicated. Norman’s perspective as an engineer proves very useful in pointing out how some engineers struggle to understand human behavior. As they are trained to think logically, they transfer this mode of thought onto their users. Unfortunately, not everyone thinks this way. Humans can be messy, unpredictable, and illogical. Human error can be factored into design rather than existing in constant conflict with the way things should work. The importance of Human Centered Design which Norman focuses on is helpful for all designers. Good design is not simply functional, but an interplay of tech and psychology. Keeping the Fundamental Principles of Interaction in mind allows designers to think more broadly about human thought and emotion. Creating experiences should be what we are striving for. 

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First, we should be thinking about how people interact with the physical objects around them. These relationships are known as affordances. A very simple real-world example is a pair of scissors (Fig.1). The holes in the handles afford the ability to insert your fingers and grasp it. The blades afford the ability to cut. The Bubble Level (Fig.2), an extremely handy app, has a variety of affordances. The user can interact with the app by placing it on a surface to measure the alignment or flatness. When the user holds it against a wall it serves as a metal detector to determine whether there are wires inside. With the app’s AR ruler setting, the user can measure the distance between two objects by pointing the phone’s camera. The app also features an inclinometer and a compass, offering affordance in several levels of spatial relation.

Another Fundamental Principle of Interaction involves signifiers. Signifiers are a component of affordances, communicating where the action should take place. Street lines (Fig.3) work as signifiers. They communicate that a given surface is a roadway and can convey different meanings such as two-way traffic, a passing lane, or the shoulder of a road. In terms of applications, the camera icon in iMessage (Fig.4) is another signifier. It visually directs the user to the camera, signifying that the iMessage app allows the affordance of including a photo with their message.

Mapping is another Fundamental Principle of Interaction and describes how the elements of two sets of things are related. A real-world example of this is button layout on Keurig coffee machines (Fig.5). The buttons correspond with the amount of coffee the machine will brew. The larger the button, the larger the cup. In many weather apps, Weather Underground (Fig.6) for example, mapping is used in the weekly forecast. The days of the week are shown in a linear way. The user then scrolls to the left to see temperatures and precipitation for the following days. This linear mapping follows the way we think of the days of the week on a calendar.

The last Fundamental Principle of Interaction I’ll be discussing is feedback. Feedback communicates the results of an actions. An excellent real-world example of this is the Sonic Research ST-200 guitar tuner pedal (Fig.7). A dotted ring of lights spirals around the outside of the note when it is played. If the note is sharp, the dots will spin clockwise. If the note is flat, the dots will spin counterclockwise. The further out of tune with the note, the more rapidly the dots will spin. As you come closer to matching the note by tighten or loosening the string, the pedal provides feedback by slowing or (if you are very lucky) stopping the spin. For example, if I need to tune a B string, I click on the pedal and play the open string. If I see the ring of lights around the ‘B’ spinning rapidly clockwise, I know the string is very sharp, and I need to loosen it to get back in tune to a B. This is very helpful for on-the-fly tuning. An example from an app is the Overcast podcast app (Fig.8), which gives the user instant feedback when downloading a podcast. After tapping the down arrow, a percentage is immediately displayed, showing the status of the download. It usually only takes a few moments but can be a good indicator of whether you have been disconnected from your Wi-Fi network.