Cognitive load is the amount of mental effort a person needs to use something, such as reading a page, filling in a form or comparing prices. On a website, the less unnecessary effort a page demands, the more attention the visitor has left for the decision you want them to make.
How cognitive load works
Working memory can only hold a few things at once. Cognitive load theory, developed by the educational psychologist John Sweller from the late 1980s onwards, separates the effort into kinds that are useful when thinking about web pages:
- Intrinsic load: the difficulty of the subject itself. Choosing a pension is harder than choosing a phone case, and no design removes all of that.
- Extraneous load: effort caused by the way information is presented. Jargon, cluttered layouts, unexplained abbreviations, inconsistent buttons and forms that ask the same thing twice all add to it.
- Germane load: effort spent actually understanding and deciding. This is the effort you want the visitor to spend.
Good design and clear writing cut the extraneous kind, so more of the visitor’s limited attention goes on the decision. Every extra thing to read, recognise or remember competes for the same small space.
Why it matters
Visitors rarely give a page their full attention. They are on a phone on the train, between meetings, or comparing your site with three others in different tabs. A page that makes them work hard to understand the offer loses them to the one that does not.
It matters most where the subject is already demanding: legal services, finance, healthcare, B2B software, or home improvements with many variables. A conveyancing page that explains fees in plain English, step by step, asks far less of the reader than one listing disbursements in a dense table. It is also an accessibility issue. People with dyslexia, ADHD or anxiety, people with low literacy, and anyone reading in a second language reach overload sooner.
Common mistakes
- Jargon in headings, such as “omnichannel solutions” or “end-to-end managed services”, which the reader has to translate.
- Walls of text with no subheadings, or pages where so much is bold that nothing stands out.
- Long single-page forms asking for details the business could collect later.
- Inconsistent design, with buttons that look different on every page or links that look like plain text.
- Making people remember things between steps, such as a reference number shown on one screen and required on the next.
- Everything at once: a pop-up, a chat widget and a banner all appearing in the first few seconds.
How to act on it
Read your most important page as a newcomer would and mark every word or step that needs knowledge they may not have. Replace jargon with plain English and check the copy’s readability, aiming for short sentences and familiar words. Give the page a clear visual hierarchy, so the eye moves from the headline to the key points to the action.
For forms, ask only for what you need now. A long form can often become a multi-step form that opens with easy questions, which feels lighter even when the total is similar. Offer sensible defaults and fewer, clearer options to avoid choice paralysis.
Then watch real people use the page. A handful of short sessions where someone attempts a task and talks through what they are thinking will show you the heavy spots quickly. Reducing load is central to how I build landing pages for ad campaigns, where every moment of confusion costs a click you have already paid for.