In 1956, George Miller, a Professor of Psychology at Princeton, published one of the most influential papers ever written on education, "The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information." In his research, Miller asserted that our brains are only capable of recalling seven items (+ or – 2) in our short-term memories. This idea is significant because we learn information by first storing it in our short-term memories before transferring it to our long-term memories where it is stored and used together with other information to create knowledge.
In the late 1980's, John Sweller, an Australian Psychology Professor, built on Miller's work by developing what he calls Cognitive Load Theory. Cognitive Load Theory suggests that our short-term memory is like a little sketch pad; it is small and keeps out large pieces of information. In order to learn, we need to break down information into digestible pieces so that it will fit into our short-term memory before it will be stored in our long-term memory.
What are the implications of this research on teaching and learning? It suggests that teachers should target learning and concentrate on discrete and small amounts of mastery in information and skills. We learn better in small doses and, therefore, presenting too much at one time prevents people from learning.
The second implication of Cognitive Load Theory is that prolonged lectures, working on two issues at once, or trying to understand a complex idea in one sitting lead to what Sweller calls "cognitive overload." If we overwhelm our short terms memories, we will not be able to learn at all.
In classrooms and with homework, educators have developed approaches to break down information into "chunks" to make it easy for our brains to learn in our short term memories. Over time, our brains then move that information into our long-term memories.
I often think about cognitive overload when students tell me they can "multitask" while they are learning. I am often tempted to respond, "Actually, the research indicates that our brains can only store a small amount of information at one time." Instead, the idea of cognitive load allows me to assist a learner who is struggling by saying, "Let's break this down, it's often easier to understand something when we look at it in smaller chunks."