In the field of UX design, certain principles from psychology can greatly impact the overall user experience. These laws help create more intuitive and human-friendly experiences.
UX design involves not only creating visually appealing interfaces but also interfaces that are easy to use and understand. Designers use psychological principles to ensure that interfaces meet users’ needs and tendencies, we’ve already tackled Hick’s Law, Fitts’s Law, and Jakob’s Law. The next principle in our series is Miller's Law.
Miller's Law is a psychological principle that states that the human brain can only process a limited amount of information at once, specifically seven (plus or minus two) chunks of information. In other words, people can only remember around five to nine pieces of information at a time. Anything beyond that becomes overwhelming and leads to cognitive overload when the amount of information is too much for our working memory to hold at one time.
Miller's Law was first proposed by George Miller, an American psychologist, in his 1956 paper, "The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information." The paper explained that people can better understand information when it is broken down into smaller chunks. This principle has been widely applied in many fields, including UX design.
Considering the extreme quantity of Amazon’s different products, they offer an intuitive user experience to display a large amount of information. To do so Amazon utilizes “chunking” and breaks down the information about different products into different categories as a form of organization. Like other e-commerce websites, Amazon uses chunking to create categories such as size, color, and features. In the image above, the left-hand menu shows the different categories after searching “couch” on Amazon. This system makes the products more memorable, helps users process information more easily, and makes better purchasing decisions.
Tubi, a streaming platform that offers free movies and TV shows, groups their recommended movies into fives. This number falls into the range of Miller’s Law and keeps the user’s attention on the movie options in front of them. This strategy is commonly replicated on most streaming services. Tubi prevents overwhelming the user with a large selection of options all at once so the user is more likely to remember and consider each movie in the set.
Figma, one of our favorite interface design applications, expertly utilizes Miller’s law in its toolbar. Instead of having every individual tool displayed in the toolbar, Figma has 8 main tool options and groups additional tools under these options. Software developers and designers often get caught up in highlighting the variety of different tools available in the toolbar without contemplating how the user’s ability to remember them all. By overloading the user with too many tools in the toolbar, the toolbar becomes less effective and tools get forgotten about. By breaking up this information into chunks, it is easier for users to remember specific tools under an option.
To apply Miller's Law in UX design, designers should focus on breaking down information into smaller, more manageable chunks.
Images, icons, and videos can be powerful tools to convey information quickly and efficiently. They help users understand the content more easily and can make the interface more visually appealing. When using images, icons, or videos in UX design, it's important to keep Miller's Law in mind. Use only the most important visuals that can convey the intended message.
For example, instead of using a series of images to explain a concept, use a video to show a step-by-step process. Or, use a single icon to represent a category of items rather than using individual images for each item. This simplifies the design and reduces the cognitive load on the user.
Long blocks of text can be overwhelming for users, especially when reading on a screen. Breaking up text into shorter paragraphs makes it easier for users to digest the information. By applying Miller's Law, designers can ensure that each paragraph contains only the most important information.
Designers can also use visual cues like subheadings, bullet points, and lists to break up the text and make it easier to read. This not only helps users understand the content but also makes the interface more visually appealing.
Progressive disclosure is a design technique that shows information gradually, only revealing what is necessary at each step. This technique is particularly useful when designing complex interfaces or when dealing with large amounts of information.
By applying Miller's Law, designers can determine which information is most important and gradually reveal it to the user. This helps reduce cognitive load and prevents users from feeling overwhelmed. For example, a form can be designed to show only the most important fields at first, with additional fields revealed as the user progresses through the form. This makes the form feel less daunting and helps users focus on providing the necessary information.
Some other tips for applying Miller's Law include:
Miller's Law is a fundamental principle of UX design that states that the human brain can only process a limited amount of information at once. To apply this principle in UX design, designers must break down information into smaller, more manageable chunks, prioritize information, and use consistent visual cues. By applying Miller's Law, designers can create interfaces that maximize users’ working memory, leading to better user experiences and avoiding cognitive overload.
If you would like to learn more about Miller’s Law, we recommend these further readings:
If you haven't read the other three installments in our UX Design Principle series try Hick’s Law, Fitts’s Law, or Jakob’s Law.
