Cognitive load
The mental effort a task demands from working memory, which can only handle a few things at once.
What problem it addresses
It explains why we make mistakes or give up when an interface makes us remember, search for or compare too many things at once.
An example
The instructions for setting up a router.
The information is the same. What changes is how much you have to hold in mind meanwhile.
Why it happens
Working memory holds few things at once.
Everything you have to remember or look for takes up part of that space.
If it fills up, we make mistakes or give up.
Applications in design
Use it like this
Show information where it is needed, without making people remember it from one screen to another.
Avoid
Asking people to copy a code from one screen to type it into another.
Don’t fall for it
Removing too much also has a cost: if information is missing, people have to go looking for it.
7 ± 2 items
What the research says
Miller (1956) proposed it as the approximate limit of what we can hold at once.
Solid evidence. Sweller (1988) showed that solving a problem can take up so much memory that less is learned. The theory was born in education; it applies to interfaces by extension. Later studies put the limit at around 4 items (Cowan, 2001).
Connections
Used in
Authors and works
- 1956
George A. Miller
Showed the limits of how much information we can hold at once.
- 1988
John Sweller
Proposed that the effort of solving a problem competes with the effort of learning.
Sources
Original sources
- Miller, G. A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63(2), 81–97. View source: Miller, G. A. (1956)
- Sweller, J. (1988). Cognitive load during problem solving: Effects on learning. Cognitive Science, 12(2), 257–285. View source: Sweller, J. (1988)
Academic reviews
- Cowan, N. (2001). The magical number 4 in short-term memory: A reconsideration of mental storage capacity. Behavioral and Brain Sciences, 24(1), 87–114. View source: Cowan, N. (2001)
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