Norman’s Seven Principles
Get introduced to Norman's seven principles of interaction design.
We'll cover the following
Norman has summarized user-centered design in his book “The Design of Everyday Things” using seven principles which are as follows:
Visibility
Reduce the gulfs of execution and evaluation by making things visible to the user. The more visible an object or option is, the easier it is for a user to learn about it.
A good example of visibility can be seen in the trade-off between the hamburger menu and tab bar. We can store various options like settings, help, terms, and conditions in the hamburger menu, but this contradicts the principle of visibility. On the other hand, the tab-bar can help in improving the visibility of features, but it can only have a few limited features.
🤔 Point to ponder
In order to apply the visibility principle, do we have to make every item and possible action visible to the user?
Feedback
The goal of providing feedback is to inform the user of the actions they have taken and the actions that have been completed. Feedback can be in any form of perception, i.e. visual, audio, tactile. For example, systems use auditory icons and earcons to produce a sound to indicate that an action has been successfully executed.
Constraints
Constraints are the limitations on actions that can be performed on the current system state. They limit the user to performing only the correct actions in the correct ways. Limitless and unconstrained possible actions in an interface can confuse the user. This makes them more prone to making errors. For example, Emirates’ online booking system does not let you select the departure/arrival prior to the current date. In the image, you can see that all dates before 16 are disabled.
Mapping
Mapping is the correspondence of a control’s layout and the device to be controlled. Mapping should feel as natural as possible, i.e. the actions should reflect our tasks in everyday life.
For example, the slider feature in an interface has strong mapping. Moving it to the left decreases its value, and moving it to the right increases the value. It can be mapped to a number line.
Consistency
If you’ve noticed the repetition of this principle, you must have realized its importance. “Be consistent” is the most important rule of interface design. An interface should have consistency in actions’ behaviors, design appearance, items placement, and arrangement.
For example, Google Docs, Sheets, and Slides have a consistent arrangement of menu options in the top bar menu with some additional options that are explicit to each file.
Affordance
The literal meaning of affordance is the quality of an object that specifies how to use that object. In an interface, the design of elements should reflect their intrinsic properties that make it easy for the user to identify and understand how to use an element. For example, this Apple logo does not have a strong affordance. A novice user cannot determine that this is actually a menu icon that can be clicked.
Point to ponder
Look at the example of the constraints principle. In the image, how can you clearly identify which dates can be selected and which dates are disabled?