The Principle of Least Astonishment (POLA) is a crucial concept in both user interface design and software development.
Sergio Vergara
Sergio Vergara
July 30, 2024 — 3 minutes reading time
What is the Principle of Least Astonishment (POLA)?
Photo by No Revisions on Unsplash
This principle, defined in the 1980s, originated in the real mobile numbers list early days of modern computing and has endured as one of the fundamental pillars of human-computer interaction (HCI). POLA posits that “if a needed feature has a high “wow” factor, it may need to be redesigned.” In other words, every part of a system should behave the way users expect, avoiding surprises or unexpected behavior.
Applying POLA to software and systems design not only involves avoiding surprises, but also ensuring that the user experience is consistent and predictable. This means that the design and structure of the system must align with users’ expectations, experiences, and mental models. Peter Morville, in his Hive Model of User Experience, highlights principles that align with POLA, such as utility, usability, desirability, findability, accessibility, and credibility.
Utility and Usability
Content should be original and meet a need (utility), and the site or system should be easy to use (usability). Minimizing the “wow” factor directly improves usability, as users can navigate and use the system without encountering surprises that interrupt their workflow. A detailed analysis of the user flow can identify points where the system’s logic might break abruptly, and adjusting these points helps create a smoother, more consistent user experience.
Desirability and Localizability
Design, identity, and brand elements should evoke emotion and appreciation (desirability), and content should be navigable and findable both on and off-site (findability). When applying POLA, designers should ensure that all visual and functional elements of the system are consistent and predictable, which in turn improves the overall user experience and makes navigation easier.
Accessibility and Credibility
Content must be accessible to people with disabilities (accessibility), and users must trust and believe the information provided (credibility). Implementing POLA also means designing systems that are accessible and trustworthy, ensuring that all users, regardless of their abilities, can interact with the system effectively and without unpleasant surprises.
Macro and Micro Interactions
In software design, attention must be paid to both macro and micro interactions. Macro interactions are the large sequences of steps required to achieve a goal, while micro-interactions are the small details and responses that occur during use of the system. Documenting and analyzing both is essential to minimize confusion. Storyboards, wireframes, and simple mockups are useful tools for visualizing and planning these interactions, ensuring that they are predictable and easy for users to follow.
Previous Experience and Learned Behavior