Definition
Cognitive load is the total amount of mental effort a user expends when interacting with your product. The concept comes from educational psychologist John Sweller's 1988 Cognitive Load Theory, originally applied to instructional design but now central to UX.
There are three types. Intrinsic load comes from the complexity of the task itself -- configuring a CI/CD pipeline will always require more mental effort than toggling dark mode. Extraneous load is friction imposed by poor design: unclear icons, buried settings, inconsistent navigation. Germane load is productive mental effort spent building understanding, like learning a new keyboard shortcut that saves time later.
PMs can't reduce intrinsic load (the task is what it is), but they can aggressively cut extraneous load and design for productive germane load. Every unnecessary decision, ambiguous label, or extra click adds to the cognitive budget users have to spend.
Why It Matters for Product Managers
Miller's Law (1956) established that working memory holds roughly 7 items. More recent research by Cowan (2001) revises that down to 4. Every piece of information you put on screen competes for those slots.
Slack understood this. Their onboarding doesn't show all features at once -- new users see a single channel with Slackbot walking them through basics. Contrast this with enterprise tools that dump users into a dashboard with 15 menu items, 8 widgets, and a modal asking them to configure notifications. The second approach has a measurably higher abandonment rate.
The PM implication: when you see a feature with low adoption, the problem might not be that users don't want it. They might not be able to find it, understand it, or muster the mental energy to learn it alongside everything else on the screen. Cognitive load is often the invisible bottleneck in feature adoption.
How It Works in Practice
Common Pitfalls
Related Concepts
Progressive Disclosure is the primary design technique for managing cognitive load -- revealing complexity only when users need it. Information Architecture determines how content is organized, which directly affects how much effort users spend finding things. Usability Testing is the most reliable way to measure whether cognitive load in your product is appropriate for your target users.