To improve students’ learning, faculty must understand the limitations of memory.
While there are several theories of memory that describe how learners take in, store, and retrieve information, the simplest theory for our purposes breaks memory into the following parts:
For the purposes of understanding memory to teach more efficiently we will only discuss a simplified version of working memory, which itself is composed of multiple parts. One important distinction for making sense with what follows is between short-term and working memory. Short-term memory holds new information, working memory consciously processes this information. Short-term memory is a distinct part of working memory. Therefore, limits of short-term memory, how much information is available for working memory to use, will have consequences for working memory and how much information a person can process. For more information about these differences, see Cowan, 2008.
We take in information from our environment (stimuli), and if we decide to process or think about it further, it is done in our working memory. For example, we may use working memory to think about the new information in relation to prior knowledge and experiences. Through this process of elaboration, the new information is more likely to be encoded into our long-term memory, from which it can be retrieved later.
It can be helpful to think of short-term memory as having slots, each holding a distinct idea or chunk of information.
Short-term memory is limited. Initially it was proposed that we can hold 7 +/-2 pieces of information at once in short-term memory (Miller, 1956), but this number was revised down to around 4 pieces of information (Cowan, 2001) depending on the type. Information in short-term memory is also short lived, disappearing after 10-60 seconds if it is not rehearsed. This short-term memory limit for “holding” information will affect the amount of information working memory has access to for “processing.”
Perhaps the most important limit for short-term memory is that while all of these pieces of information are able to be held, only one is available at a time (Garavan, 1998; Bleckley et al., 2003; Basak & Verhaeghen, 2011). Accessing one of the other pieces of information means switching focus away from the current conscious piece of information.
The amount of information that working memory is processing at any given time is called cognitive load (Sweller, 1988). When there is more information than can be processed by a learner’s working memory, we experience cognitive overload. This overwhelming and uncomfortable feeling means we are unable to process additional information, and therefore unable to encode new information into long-term memory. How much cognitive load we are able to handle is dependent on many factors such as age, expertise and emotional state.
The finite capacity of working memory is a bottleneck to learning and has several consequences for learners.
Working memory limitations mean that multi-tasking does not exist. Instead, we switch our attention quickly between different tasks, but this comes at a cost for more than 98% of learners: they take longer to do tasks and make more errors when task-switching than when focusing on one task at a time (see Multitasking).
How information is presented to students will affect the efficiency in which they’re able to take in and process content. The Cognitive Theory of Multimedia Learning (CTML) explains why these effects occur and suggest several ways to better present information to learners (see Multimedia Learning).