Miller’s Law: The simple reason behind high bounce rates

 Why our brains rebel against overloaded UIs

Your brain has a defined method of how to process complex information. Open a publisher website or app and you are confronted with a decision on which content to view. This decision has to take into account the value of many different propositions, headlines, colors, and images. The effort required to process this is known as the ‘cognitive load’ and is hardwired to the success of your UI/UX.

The information age gives us access to more data, images, whole waves of information. It is more than we were ever evolved to process. This means the processing power of the brain is still limited in very specific ways. For digital publishers, pushers of this information, it is easy to overload the cognitive load with their UI/UX.

This is because the cognitive load, or the learning and working process of navigating the website, is managed by the ‘working memory’.

The limitations of your working memory is why your brain can feel like a burst of static when faced with a wall of information. There is a defined limit to the working memory.

The average person can only maintain 7 (give or take 1 or 2) items in their working memory. This information is then stored in the prefrontal cortex for just 15-20 seconds.

This is Miller’s Law

Give your readers too much information and they will be unable to process it. This results in stress and frustration with the interface, your website.

In a list of 20 articles, we will not remember all 20 for a long enough time to make an informed decision about which to read. This is a ‘heavy cognitive load’.

See again, stress and frustration. The job of UI/UX is to give your brain a framework to make this processing possible, even with large amounts of data.

However, digital publishers need to display a lot of information. It’s not feasible to limit each page to seven to nine units of information.

One way to counteract Miller’s law is by ‘chunking’, assembling varied isolated pieces of information into a cohesive whole that is perceived as more than the sum of its parts.

Let’s try some examples

How words are formed is a simple example. Consider the word ‘watermelon’, it’s a clear piece peice of information. Now try to memorize the letters out of order: e a w r m n e l m o t — the cognitive load of the same elements of information becomes much higher. Static. The heavy cognitive load means that you probably didn’t notice that we added a second ‘m’.

Next, try looking at the image below and the objects in each.  The objects on the left are easier to memorize because they are ‘chunked’ into a larger, conceptual group. They are connected under the concept of the ‘classroom’. The image on the left is 8 separate concepts, about at the limit for our working memory.



How can digital publishers apply this principle?

For digital publishers, a list of 20 articles, grouped into chunks by category helps the reader make easier decisions. The reader can then entirely discount categories they are not interested in. This reduces a list of 20 articles into three or four categories that can be handled by the working memory. If the reader wants more detail each category should use the same principle to give the brain workable amounts of information.


Marfeel uses Miller’s Law in the UI/UX designs of mobile websites. In this example the cognitive load is in the sweet spot, giving the reader five items to process with the working memory.

So, how we do we define and create chunks of content that contain multiple elements, such as images and headlines?

We rely on another psychological factor that affects how our brains perceive information, the gesalt proximity principle. Viewers see objects grouped closer together as belonging together.

In addition, we can have multiple interpretations of the same information based on how we choose to perceive it.

Imagine a goblet or a vase and that’s what you will see, imagine two people face to face and the image shifts. This is known as the figure and ground principle, in which your perception can switch between perceiving an object and its surroundings.

This theory of perception proposes that people make sense of the world around them by talking separate and distinct elements and combining them into a unified whole.

We can choose to isolate each element of the page or view it as a whole chunk, containing image, headline, and category. Our brain naturally desires a lower cognitive load so we opt to group the information into something manageable.

This leaves the reader with a choice between five chunks, rather than 15-20 elements.

You can choose to look at each element in isolation, see a headline, a broader category, and an underlined overlayed across five images, or view the unified whole.

This helps inform more intuitive UX by minimizing and grouping information into ‘chunks’ or categories. Therefore, the Gestalt Principles of Visual Perception means readers can build complete pictures from varied information.

Reduce the number of elements at each navigational stage — and keep them organized, not exceeding 9 bits. Your readers may not remember each element, but they will remember the path to access the relevant chunk.

Conclusion: Publisher UI/UX should be adapted to our limited brains

Well-designed UX uses the limitations of how our minds work to build UX that works to your advantage. Websites that have a high cognitive load feel like work, they feel unfamiliar, and they make us distrust the site.

Marfeel helps to make mobile websites that encourage reader retention by limiting the cognitive load, grouping into categories and linking similar elements. Users then perceive these ‘chunks’ at either the object or the surrounding level.

The end result is a lower cognitive load and a simpler process that still gives the reader a choice.

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