Cognitive Load

Cognitive load refers to the total amount of mental effort being used in working memory during a task. The concept was developed by John Sweller in the 1980s and has become a central construct in cognitive psychology, cognitive engineering, and instructional design. It distinguishes three types of load: intrinsic load (determined by the complexity of the task itself), extraneous load (imposed by poor design or unnecessary information), and germane load (the productive effort of integrating new information with existing knowledge).

The principle of cognitive load has direct implications for the design of complex systems. An interface that forces the operator to hold information in working memory that the system could have displayed is imposing extraneous cognitive load. The Air France Flight 447 accident is a case study in cognitive overload: the pilots were required to process contradictory sensor readings, maintain spatial orientation, diagnose the failure, and fly the aircraft simultaneously — a set of demands that exceeded the capacity of working memory under stress.

Cognitive load theory has been criticized for treating working memory as a fixed-capacity container rather than a resource that can be expanded through expertise and distributed across artifacts. The distributed cognition perspective argues that the relevant unit of analysis is not the individual's working memory but the cognitive system as a whole, including the tools and representations that offload memory demands.

• Cognitive engineering — the field that applies cognitive load principles to system design
• Working Memory — the cognitive system that bears the load
• Distributed Cognition — the alternative perspective that distributes load across the system
• Mental Models — the knowledge structures that reduce cognitive load through pattern recognition