The Design of Everyday Things

In my work, I've found that our interactions with the world are governed by a few simple, yet powerful, psychological principles. The most important of these are affordances, signifiers, mappings, and feedback. An affordance refers to the relationship between an object and a person—the properties that determine just how the object could possibly be used. A chair, for instance, affords sitting. However, affordances must be perceivable, which is where signifiers come in. Signifiers are the clues—the signs, labels, or sounds—that communicate where and how an action should take place. A 'Push' sign on a door is a signifier.

Good design also requires a clear mapping between controls and their effects. Think of a stove: the layout of the burners should directly correspond to the layout of the control knobs. When this mapping is illogical, we are forced to experiment and memorize, increasing the chance of error. Finally, feedback is critical. It is a way of communicating the result of an action. A click sound, a light turning on, or a progress bar are all forms of feedback that reassure the user that the system is working and their action was successful. When these principles are ignored, we are left with objects that are confusing and frustrating.