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You may have heard that people can process seven (plus or minus two) chunks of new information at a time in working memory. Many of us wish we had even more room than that.
Cowan defines short-term, or working memory, as “the collection of mental processes that permit information to be held temporarily in an accessible state, in the service of some mental task.”
image courtesy office.microsoft.com
Sadly, seven new items turns out to be more than we can process at once. So, what’s a better number? The best answer we have today is three, maybe four.
The misunderstanding stems from an article that George Miller wrote in 1956 called “The Magical Number Seven, Plus or Minus Two.” In this article, Miller notes the many times that the number seven shows up in everyday life, but he also suggests that this may be a coincidence. Although he points out that there is a limit to how much information we can process at one time (so true), he does not actually say that we have seven plus or minus two slots in short-term memory. Shriffrin & Nosofsky wrote a review of how this misunderstanding came to be and more on the capacity of our working memory.
Only three? Maybe four? Sorry.
Still, it’s helpful to acknowledge that learning something new requires a fair amount of mental effort—perhaps more than we expect.
We want to avoid giving people (learners, employees) too many novel things to work with at once. Trying to stuff too many things into working memory results in cognitive overload.
Cognitive overload occurs when the demands on working memory are too great. It inhibits learning and problem solving, and it can reduce the available space in working memory enough to cause errors and to reduce learning and performance.
Taking this into account when sending out information, designing instruction, or giving a talk greatly increases our ability to transmit complex concepts and tasks.
Designing with cognitive overload in mind is a bit complicated, because what’s new to one person will not be new to another. Prior learning and experience, which of course varies, makes an enormous difference. An example people often use to illustrate the difference that expertise can make is about master and novice chess players. A novice at chess sees every piece and each move as one new piece of information, but a chess master sees the whole board as one chunk of information. For a novice, just working out the next move can be daunting. For the chess master, the next likely series of moves and a host of variations will be obvious.
So knowing your audience and especially their prior knowledge, is key.
Here are four things you can do to avoid cognitive overload:
- Make connections. Help learners see how what they are learning is related to things that they already know. For example, point out similarities between a familiar idea or task and one that they are learning.
- Highlight key points. Identify the most essential parts of what people are learning. For example, point out the pivotal step in a procedure or the most critical aspects of a new concept.
- Streamline information. Don’t introduce extraneous elements that make learning more difficult. For example, avoid using graphics that do not directly support what you are teaching, and avoid cluttered slides or other materials.
- Provide scaffolding. Give support to help learners grasp complex ideas, procedures and problems that would be impossible (at first) without help. For example, give a model or outline (advance organizers) to help learners organize new information, start with easy topics and work up to those that are harder, or teach complex topics in small steps that build on one another.
For more on designing for complex cognitive skills, see van Merriënboer & Kirschner’s Ten Steps to Complex Learning.
We sometimes want to throw new knowledge and skills at our learners as rapidly as possible. But realizing there are limits to how much we can process at one time can give us guidance for designing learning programs that work.
For more on the magical number seven and cognitive overload, see “From the Research: Myths Worth Dispelling: Seven Plus or Minus Two.”