User memory considerations in UI design
Memory is the ability to encode, store, and retrieve information and experiences. It is essential to our lives. We rely on memory to help us remember our identity and that of others, our past experiences, and potential threats. There are three memory systems: Sensory, Short Term, and Long Term. All of the time, our five senses are storing all the environmental stimuli, filtering it, and discarding irrelevant information. When the stimulus has ended and an impression remains, it is temporarily recorded in our minds. This is known as Sensory Memory. It often happens unconsciously and only lasts split seconds.
Our mind then goes through two processes to get the information from sensory Memory to short term memory. The first process is pattern recognition, where we actively search through our long term memory to find a matching pattern for the new data. The second process involves focusing our attention on the stimulus until it moves into our short term memory where it is encoded mainly through hearing and seeing.
Our short term memory, or STM, only lasts 30 seconds and has limited capacity to store information because it all occurs in the frontal lobe of our brain. There is no definite number to how many items we can store in our STM at once. One theory suggested there was a capacity of 7 plus or minus 2, but this has been disproved and is now suggested to be even lower. By grouping information into meaningful groups we can optimize our STM.
After we stored the information temporarily in our STM we encode the information semantically by creating mental associations and with frequent rehearsal in our long term emory, or LTM, which is spread all throughout the brain in our neural connections. The final act our memory performs is retrieval, where we pull the memory out of storage and reverse the process of encoding.
In a study conducted by Intons-Peterson et. al, both younger and older adults were asked to remember the following list: candy, sour, sugar, bitter, good, taste, tooth, nice, honey, soda, chocolate, heart, cake, eat, and pie. They were then asked to take a minute to write down all remembered words. The next test involved that subjects consider the words taste, point, sweet and identify which word was included in the original list. An overwhelming 80-90% of participants confidently, but incorrectly, selected the word sweet. While the word sweet yields a close association to the presented collective of words, this association should not nullify the fact that its selection still results in a memory malfunction.Incidents such as these are reminders of our memory's fallibility.
In terms of UI design, our memory's fallibility falls into the following categories: transience, suggestibility bias and misattribution. Transience is the weakening or loss of memory over time, regardless of age. For example, you might clearly remember what background you chose for your MySpace profile back in 2001, but now it's a vague memory. Suggestibility is information that is inaccurately added to memories due to leading questions and suggestion. This commonly happens to eyewitnesses to crimes being repeatedly interviewed as their stories change based on the questions, but can also happen during the interview stages of UX research with SMEs and users. Bias is the editing or rewriting of past memories skewed by our current knowledge and beliefs. Misattribution is assigning a memory to the wrong source or context.
Our memory's fallibilities are relevant to the user research stage. When we conduct interviews with users, they need to take what is said with a pinch of salt. Self reporting is often inconsistent due to the fact that memories are not as accurate as we'd like to think they are. In addition, if the user hasn't used a similar system in a long time, their memory may have decayed . Memories we don't use are erased from our Long Term Memory. Tt's expected that human memory will err. This is why it is crucial to conduct observational user research instead of user interviews.
In the design phase, we should pay attention to our memory's fallibility. With Short Term Memory only lasting 30 seconds at best, a conscientious interface would ensure that users will not have to remember every step in a task flow, but will be guided easily through it. Because of the limited capacity for STM, we should not bombard users with too much information all at once that they will never be able to focus on and remember for more than a few seconds. Designs should direct the users' attention to the task at hand.
We can help our users store more information in their STM by using visual cues to make information stand out and positioning information to suggest relationships . This will help them effectively navigate our system and pinpoint key information they need to remember. Maintaining consistency throughout navigation menus and with interaction patterns means that the user only has to program their mind once to this behavior.