Memory consists of – among others – long-term, sensory, and short-term memory. Each of them differs in how long the information is kept for and how it is processed. Short-term memory is the so-called working memory and stores small amounts of verbal and non-verbal data. It is associated with focused attention and processes current information, which is the first stage of its long-term memory consolidation.
Why is short-term memory crucial for interface design? Because this is what the user uses when interacting with products. According to George Miller, a human can directly distinguish 7 pieces of information at once, which means that we can remember about 7 (+/- 2) elements simultaneously. Additionally, sensory memory, by capturing information, transfers it to the short-term memory store. It is worth noting that data is stored for 0.5 seconds for visual sensations, and the short-term memory capacity is 30-40 seconds.
Therefore, when designing interfaces, avoid any distractions because the information disappears after about 20 seconds. When the user has to rewrite or remember something from the previous page or tab, it is also unfavorable to achieve their goal.
We use short-term memory to remember the name of a person we recently met or a telephone number that we need to use soon. Therefore, it is easier to remember, for example, a number consisting of 3 groups consisting of digits (XXX-XXX-XXX) than a long sequence of all 9. When designing a menu or tabs, we should use the optimal number of items, i.e., from 5 to 9. Of course, we do not always have to limit ourselves to 7; users need to recognize items rather than memorize them.
It is good practice to use signed pictures or icons because pictures are easier to remember than words. Similarly, according to the serial position effect, we remember the first and last elements better. The first one for long-term memory and the last one for short-term memory, while the elements placed in between are not remembered so easily. This action can be used to highlight products on the store’s website. This is the case, for example, in OLX, where the highlighted ads are first on the list or in website navigation or grouping items.
It is also worth remembering the feedback, or rather about the user’s waiting time for a response. Before the user forgets what they were doing, we should load information or another page as soon as possible. Another solution may be to change the clicked hyperlink color or gray out the product or article list, the details of which have already been reviewed. Thanks to this, the user will immediately see what they shouldn’t be clicking on for a second time.
Another example is the use of placeholders in input fields. If we design our forms with fields to be completed so that the placeholder disappears when there is a cursor in the field, and we do not apply, e.g., a label for such a field, the user may forget what data was to be entered in this field. Therefore, it is always a good idea to leave a field label so that the user does not have to leave that field to make sure what information should be entered there.
Cognitive Load Theory / CLT is another concept that must be kept in mind when designing interfaces. Just as short-term memory is limited, so is our brain’s computing power. Cognitive load is related to the amount of information your working memory can store simultaneously. Sensory memory filters out most of the information that reaches us but retains the most important elements long enough to enter working memory.
This means that when performing an activity, e.g., throwing a shuttle, our sensory memory rejects information from the environment, such as noises, smells, other people, and focuses only on the shuttle. Information from sensory memory is transferred to working memory, where it is processed or discarded.
It’s worth recalling that working memory can store about 5-9 items at a time, which has a huge relationship with cognitive load. When the brain processes information, it categorizes it and transfers it to long-term memory, where it is stored created in structures of knowledge called “schemas”. They organize information according to its use, such as diagrams for different concepts such as dog, cat, mammal, and animal. We also have behavioral patterns such as cycling.
According to John Sweller, cognitive load refers to the amount of information that working memory can hold at any one time. In other words, the term describes the mental effort required to absorb new data. Why is this information important for interface design?
Although browsing websites does not require a mental effort, users must learn how to use a given website, e.g., that specific website’s navigation, as they do with learning any new material. The cognitive load also applies to limitations and requirements directly resulting from the user’s goal, e.g., on the store’s website, it is the price or size of the product.
When designing navigation, it is worth using, for example, card sorting to help users find the right information in the right place. Avoid excessive distractions, such as graphics unrelated to the content. Also, beware of electoral paralysis by using too many hyperlinks, pictures, or buttons. The more choices we present to the user, the longer it will take for them to decide and the greater the cognitive burden they feel when making decisions.
Therefore, when developing solution proposals, it is best to focus on no more than 2 options to choose from. When using iconography, let’s try to make it legible and understandable. Otherwise, they can be burdensome for the user, which is best illustrated by the recent changes in this area introduced by Google for its products, which have circulated the internet as a meme.
This example can cause problems with cognitive overload. Also, its design is very problematic for people with certain visual disabilities – they simply will not be able to distinguish these iconographies.
Behavioral psychology helps design products that minimize cognitive load and avoid the complex process of analyzing and making decisions. Users are not looking for the optimal solution to a problem but are satisfied with the first “good” solution – it must minimize the cognitive load. Therefore, let’s try to use simple rules and dependencies to help them complete the task in interaction with our products, without straining short-term memory and cognitive load.