Miller’s Law

Miller’s Law: the number of perceptual ‘chunks’ an average human can hold in working memory (a component of short-term memory) is 7 ± 2.

A Wikipedia summary of the full paper is below:

In his article, Miller discussed a coincidence between the limits of one-dimensional absolute judgment and the limits of short-term memory. In a one-dimensional absolute-judgment task, a person is presented with a number of stimuli that vary on one dimension (e.g., 10 different tones varying only in pitch) and responds to each stimulus with a corresponding response (learned before). Performance is nearly perfect up to five or six different stimuli but declines as the number of different stimuli is increased. The task can be described as one of information transmission: The input consists of one out of n possible stimuli, and the output consists of one out of nresponses. The information contained in the input can be determined by the number of binary decisions that need to be made to arrive at the selected stimulus, and the same holds for the response. Therefore, people’s maximum performance on one-dimensional absolute judgement can be characterized as an information channel capacity with approximately 2 to 3 bits of information, which corresponds to the ability to distinguish between four and eight alternatives.

The implication here for product design is always organize elements of information in groups no bigger than 9, but preferably ~5 chunks.

Here’s an example of what this looks like in practice:

The most important rule in UX design that everyone breaks (source)

This can also be applied to our every day lives. At a certain point, tools and apps can help us be more productive but we too can only process a finite amount of information in our day-to-day work and therefore, reducing the number of tools or applications can actually reduce cognitive overload and help us reach and maintain a flow state more often. When it comes to productivity and task completion: less is more.

For more on Miller’s law check out the full paper here + check out this great medium post which has a 2 minute test you can do to test how much info you can hold in your working memory.

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