Usability and User Interface Design Terms Explained: Psychology of Usability

What role does the psychology of usability play in user interface design?

Usability is inextricably linked to psychology. In relation to user interface design , usability is the study of the ease with which people can employ a software tool or web application in order to achieve a particular goal. Usability applies to any human-made object, but for this article I'm going to discuss the psychology of usability from a user interface design perspective. In computer science, usability of user interface designs specifically focuses on evaluating how clearly and effectively a user can interact with a particular user interface. Often usability is considered a part of user experience. The study of usability is empirical in nature, and measuring usability requires a form of quantitative analysis. The end goal is to create user interface designs that are intuitive, easy to learn, efficient to use, and memorable in terms of learned functions. Other factors include subjective satisfaction and the frequency and severity of errors when using a website, web application or other kind of software.

How does the psychology of usability help improve user interface design?

Usability follows the behaviorist paradigm of psychology in that observable behavior is recorded for analysis. This data is then used to create interface designs with the best user experience possible. In order to achieve this a profile of a user has to be created. What is the target audience? What tasks do they need to accomplish using the interface design in order to achieve their goals? The answers to questions such as these allow the interface designer to create user profiles, personas and scenarios of use. The latter are also known as use cases, and they represent specific tasks such as signing up for an online service. Iterative design processes are usually employed to constantly improve an interface design through usability testing. This can be done in a process of creating prototypes of a software, or rather its proposed UI design (for example through the use of a prototyping or wireframing tool), testing it for usability issues (preferably with end users), and going back to the drawing board with knowledge gained to repeat this cycle until a workable user interface design can start being transcribed to code.

What kind of insights does psychological inquiry bring to interface design?

Insights gained from psychology research reveal, for example, the attention span of web users. Lab experiments have helped interface designers to model and measure human performance in terms of problem solving, memory, motor control, and perception among others. This is how and why some websites offer feedback and/or suggestions regarding passwords. Cognitive psychology and neuroscience, by telling us about how people think, make decisions, remember things, or even get distracted, are invaluable in creating user interface designs that score high on usability. An example of this is George Miller's studies that show that human short-term memory can cope with about seven (give or take one or two) simultaneous choices. The application of this knowledge has led many interface designers to limit menu choices to around five if they can help it.

What are examples of data gathered when seeking to improve interface designs?

The kind of data gathered during the usability testing of a UI design includes, among many others, eye tracking data. This can be either the point of a users' gaze or the motion of the eye relative to the head. Eye tracking monitors track every eye movement and are used to visually highlight the most active areas of an interface design. This information is used to gauge how quickly users learn an interface design's system, layout and structure. Mouse tracking (tracking movement and clicks) is also used in the same vein. These are what helped establish usability and interface design conventions such as access to login processes and search bars mostly being found on the top right of a user interface design. Other insights gained from psychological methods include the demarcation of the fold. This is the lowest point where the interface design of a website is still visible on the screen. The region above the fold is the part of a website that is visible without scrolling. Usability testing provided anecdotal evidence of many users who stuck to the region above the fold, thus encouraging interface designers to make more effective use of that region.

Overall, psychological factors have an astounding impact on how efficiently and readily people use different software applications and websites because or despite their user interface design features. This is just one of the reasons why usability is or should be such an important consideration when developing a user interface.

Article By Martin Matz