Miller's Law
What does Psychology and User Experience have in common? Everything. Studies conducted by George Miller indicate that most people can store 5 to 9 items of information in their short-term memory. This rule can and must be easily applied to presentations, listings and menus.However, as it happens for instance with a clothing e-commerce website, it is not mandatory to only list 5 - 9 items per page, since the intention is not to make the user memorize things, but to see these items.
First, the information is received in the sensory storage, for a fraction of a second after the stimulus is gone, then it is moved to the short-term storage, which only retains a certain amount of information for less than 1 minute. After going through the short-term storage, information is forgotten or, if it happens to be processed, by repetition for instance, it can reach the long-term storage, where it can stay indefinitely in that compartment of unlimited capacity.
The short-term memory is a simple registration system for the active items, consisting on their immediate recollection, and it can be analyzed through three different dimensions, with these being the capacity, the length and the codification or processing (Pinto, 1997). The capacity is the amount of information which can be stored, and this is limited in terms of the number of items stored, the length of the items and the availability of mental resources to carry out the STM operations. There are limits in what concerns the amount of information that one can retain in a given moment, and there are also limits in the quickness through which one can use the cognitive functions to process the information received by the system.
One of the most used evidences to prove this is the memory range of numbers. The results obtained from it, when applied to young adults with an average education, are around seven digits, plus or minus two, just like Miller had proposed with his idea that the immediate memory or short-term memory can hold around 7 plus or minus 2 categorized units. The length is the amount of the time during which the information is retained, and this is also limited, ranging from 15 to 30 seconds, without requiring a renovation of information through repetition.
Many UX designers misunderstand Miller's number seven by thinking that humans can only process seven chunks of information at a time. As the result, they place unnecessary design limitations for websites that undermine their UX. The most important thing that UX designers have to understand about Miller’s law is that human short-term memory is fairly limited, so if they want to increase knowledge retention, they should use chunking. Chunking refers to breaking up content into digestible and distinct pieces of information instead of presenting one, large piece.