Cognitive Principles
Mental Models
Users arrive with expectations from past experience — break those without reason and you cause confusion.
Where it comes from
The idea has deep roots in cognitive science — the psychologist Kenneth Craik described the mind building 'small-scale models' of reality as early as 1943 — and was carried into interface design by usability researchers, the Nielsen Norman Group prominent among them.
Why it matters for your website
Users don't arrive with a blank slate. Mental models are the expectations people bring from everything they've used before. When an interface violates those models without a compelling reason, the result is confusion, not delight.
A mental model is the picture a user already holds of how something works, assembled from every comparable thing they've used before. Your interface isn't judged on its own logic — it's judged against that pre-existing picture, and where the two disagree, the user trusts the picture and concludes your site is broken.
This is why 'it makes sense once you understand it' is not a defence. Most visitors will never invest the effort to update their model; they expect a shopping cart, a back button, or a settings page to behave the way those things always have, and a clever reinvention mostly buys you confusion.
Wrong vs right
A 'cart' that doesn't store items for later but checks out instantly, contradicting what every user expects 'cart' to mean.
A cart that behaves like a cart — holds items, lets you review and adjust — matching the model the user arrived with.
A settings page where toggles save immediately, with no save button, on a site where everything else needs explicit saving — an inconsistent internal model.
Consistent save behaviour across the product, so the user's model holds everywhere.
Renaming common features with invented terms, forcing the user to learn a new vocabulary for familiar things.
Using the words and patterns users already know, so their existing model maps straight onto your interface.
Understanding Mental Models
A mental model is a person's internal understanding of how a system works — what it can do, how it responds, where things live. People build these models from accumulated experience and then use them to predict and act. When they reach for the back button, expect a logo to link home, or assume a trash icon deletes, they're running a mental model, not reading the interface afresh.
Good design works with the models users already have rather than imposing a new one. The closer your interface sits to a visitor's existing expectations — drawn from competitors, from platform conventions, from the wider web — the less they have to learn and the more competent they feel. A mismatch between your system's actual behaviour and the user's model is a frequent, and usually avoidable, source of confusion.
When you must diverge from an existing model — because your product genuinely does something new — the burden falls on you to bridge the gap with clear signifiers, feedback, and language. The cost of violating a mental model is paid every time a new visitor arrives, so reinvention has to clear a high bar of genuine benefit. It connects directly to Jakob's Law, the match between system and real world, and information scent.
How Kweri checks it
Mental models are partly inferable and partly a matter of domain knowledge. Kweri can flag some recognisable mismatches — for instance familiar elements behaving in unexpected ways, or invented terminology where a standard word exists — by reasoning about common conventions. But knowing your specific users' expectations, shaped by your particular market and their prior tools, is something only research into your audience can fully establish. So Kweri raises likely model violations against general conventions, and prompts you to validate them against what your real users expect.
FAQ
What is a mental model in UX?
A mental model is the internal picture a user has of how a system works, built from past experience. People use it to predict how an interface will behave, so designs that match users' existing models feel intuitive and those that violate them feel confusing.
Why do mental models matter in design?
Because users judge your interface against the expectations they already hold, not against its own internal logic. When behaviour contradicts the model, users assume the product is broken or behaving wrongly — even if it's working exactly as designed.
How do I design for users' mental models?
Follow established conventions, use familiar terminology, and make elements behave the way comparable products do. Where you must do something genuinely new, bridge the gap with clear signifiers, feedback, and explanation so users can update their model easily.
What happens when a design violates a mental model?
Users get confused, make errors, and lose trust — and the cost recurs with every new visitor. Because most people won't invest effort to relearn, a clever but unexpected pattern usually loses more in confusion than it gains.
How are mental models related to Jakob's Law?
Jakob's Law is essentially a mental-models argument: users spend most of their time on other sites, so their model of how a site should work is built from those. Matching that shared model is what makes your site feel familiar.
Related principles
Users spend most of their time on other sites, so they expect yours to work the same way.
Speak the user's language — use familiar words and conventions, not internal jargon.
Users follow the strongest-smelling trail toward their goal — they click links whose labels and context suggest the destination will be relevant, and abandon paths that go cold.
Good design externalises the knowledge users need to act — it puts it in the world, not in their heads. A product that requires memorisation is a product that requires training.
Attribution & sources
Identified by Nielsen Norman Group (concept rooted in Kenneth Craik, 1943). Catalogued from Nielsen Norman Group — Mental Models.
A foundational cognitive-science concept (Craik, 1943) applied to UX; the linked NN/G article is the reference used here.
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