The amount of mental resources needed to understand and interact with an interface.

Cognitive Load is a psychology concept closely related to Miller’s Law.


  1. When the amount of information coming in exceeds the space we have available, we struggle mentally to keep up — tasks become more difficult, details are missed, and we begin to feel overwhelmed.
  2. Intrinsic cognitive load refers to the effort required by users to carry around information relevant to their goal, absorb new information and keep track of their goals.
  3. Extraneous cognitive load refers to the mental processing that takes up resources but doesn't help users understand the content of an interface (e.g. distracting or unnecessary design elements).


Cognitive load theory was developed in the late 1980s  by John Sweller out of a study of problem solving and was in many ways an expansion on the information processing theories of George Miller. Sweller argued that instructional design can be used to reduce cognitive load in learners, culminating in his 1988 publication of “Cognitive Load Theory, Learning Difficulty, and Instructional Design”. Researchers later on developed a way to measure perceived mental effort which is indicative of cognitive load.


Further Reading