Mental model diagrams

011 min

Why teams draw mental model diagrams

Picture a product team at a cinema chain's ticket website. Their backlog holds seat maps, trailer previews, a loyalty scheme and a snack pre-order. Every planning meeting ends in the same argument. One person wants loyalty points, another wants a faster checkout, and a third wants better trailers. Each of them speaks for the customer, and each describes a different customer.

So the team tries something new. Over a few weeks they hold long, open conversations with people who go to the cinema. They do not ask about the website. They ask how people decide to see a film at all.

What they hear does not match the backlog. People talk about deciding whether a film is worth an evening out. They talk about finding a time that suits three friends. They talk about lowering their hopes before a sequel so they are not let down. Very little of it is about choosing a seat.

Now the team has two sets of notes: what people said, and what the company built. Nothing connects them yet. A mental model diagram is the tool that puts both sets on one page, so the team can see which needs the product serves and which it ignores.

022 min

How a mental model diagram is structured

A mental model diagram has two halves, split by a horizontal line. The top half describes people. The bottom half describes the organization. Indi Young, who created the method, calls the top half a skyline, because its columns of boxes look like a row of tall buildings seen from a distance.

The top half is built in three levels:

Each box describes what goes on inside a person: a thought, a reaction, or a rule they follow. It starts with a verb, and Young now calls the boxes windows, since they sit in towers. A box never describes the website. Click the showtimes tab is about the tool, not the person, so it does not belong in the top half.

The bottom half lists the organization's support. Support is anything that helps a person with a tower: a feature, a page, a phone line, a member of staff, a policy. Each piece of support sits directly under the tower it serves.

The diagram is arranged by purpose, not by time. A journey map runs from left to right as events happen. A mental model diagram groups thoughts by what the person is trying to do, whenever they happen. Two boxes in the same tower may come weeks apart.

This layout is why the method works. The top half never mentions the product, so it stays true when the product changes. Support is lined up under it, so any tower with nothing underneath stands out. The team does not have to argue about whether a need is ignored. They can see it.

032 min

Where mental model diagrams come from

Indi Young traces mental model diagrams to a consulting job at Visa in 1993 or 1994. She worked on it as the interaction designer, alongside developers and business analysts. The analysts had not mapped how customer service staff did their work, so she built a workflow table for them in Microsoft Excel. It looked like a state diagram, a computer science chart that shows each state a system can be in and the moves between those states.

At first the table held only behaviour. Young kept emotions and beliefs out of it. Over the next few years she spent more time listening to people. From 1997 to 1999 she refined non-directed interviews, where the researcher follows what the person wants to talk about instead of a script.

The first aligned diagram

In 2000 she drew her earliest mental model diagram for a client, to show where its product helped its business customers, who worked with geospatial data, and where it fell short. That was the step that made it a mental model diagram: the customers' thinking on top, the client's product lined up below. It showed the client something its own feature lists could not, which was the customers' work that the product did not touch.

Young was a founding partner of the design agency Adaptive Path in 2001. In 2008 her book, Mental Models: Aligning Design Strategy with Human Behavior, was the first title from the publisher Rosenfeld Media. It turned one consultant's working method into something any team could follow.

The method has a named originator, but it is not a law with an experiment behind it. It is a research and planning practice. Its value comes from the quality of the listening that feeds it, not from a measured effect.

042 min

How to make a mental model diagram

Back at the cinema chain, the team now has hours of recorded conversations. Turning them into a diagram takes five steps.

1. 1

   Scope by purpose, not by product.

   The cinema team's scope is going to see a film, not using our website. A scope tied to the product only finds the needs the product already knows about.

2. 2

   Listen.

   Hold one-to-one sessions with open questions, such as Tell me about the last film you went to see. Let the person lead. Record and transcribe each session.

3. 3

   Comb the transcripts.

   Read each one slowly and pull out every passage where the person describes their thinking, a reaction or a rule they follow. Write each one as a short summary that starts with a verb.

4. 4

   Group from the bottom up.

   Put summaries that serve the same purpose together to form towers. Then put towers that share a larger goal together into mental spaces. Name each group only after it has formed.

5. 5

   Check what you have.

   Look for thin towers that need more listening before you draw the final version.

Step 3 is where most diagrams go wrong. Young separates inner thinking from three things that look like it: facts about the world, preferences, and descriptions of using a tool. I like the back row is a preference. Sit where nobody can kick my seat is a rule, and it explains the preference. Young's check is what she calls the hallway test. Ask what the person thinks about while they walk down the hallway on the way to do the thing.

For the cinema team, combing turns a long, wandering answer into boxes such as Ask the friend who always picks well, Avoid trailers that give away the ending and Lower my hopes before a sequel.

Tools can draw the final picture from a spreadsheet of summaries, and Young offers one herself. The combing and the grouping are still done by people, because they depend on judging what each person meant.

Where the bottom-up grouping comes from

Step 4 borrows the logic of an older tool. The affinity diagram, which the Japanese anthropologist Jiro Kawakita devised in the 1960s, sorts many separate notes into groups by how they relate, with no list of categories decided in advance. That is why it is also called the KJ method. A mental model diagram is an affinity diagram with one strict rule added: every note must describe what goes on inside a person. Grouping this way is slow. But it stops the team from sorting what they heard into categories they already had in mind, such as their own feature list.

052 min

Reading the gaps in a mental model diagram

Once the towers are built, the team turns to the bottom half. They list everything the cinema chain offers that touches going to a film: the showtime list, the seat map, trailers, critics' reviews, the loyalty scheme, the snack pre-order and the phone line. The team writes each feature on a card and places it under the tower it serves.

Some cards fit two towers. The trailer page sits under decide whether a film is worth the evening and, less strongly, under build excitement before the night. Young's method allows this as a primary and a secondary alignment. Some towers fall outside anything the company will ever do, such as find someone to look after the children. The team marks those as out of scope instead of counting them as failures.

Then the pattern shows. The seat map, the loyalty scheme and the snack pre-order all sit under one small tower about the visit itself. The tower agree on a time with friends has nothing under it. People described sending pictures of the showtimes to a group chat, waiting for replies, and losing the seats they wanted. The website knows every showtime, yet it plays no part in that.

This is what the diagram is for. Young describes the finished diagram as a view of where an organization supports the way people think, and where it does not. A gap can be one of three things:

• No support. Nothing sits under the tower.
• Weak support. Something sits there, but people in the sessions said it did not help.
• Harm. A feature works against the tower, such as a timer that releases held seats while friends are still deciding.

In Young's early consulting work, the mental spaces also became the plan for a website's information architecture: the way its pages are grouped, named and linked. Each mental space suggested a section of the site, because it matched a goal people already had.

The cinema team now has a different argument. It is no longer loyalty points against trailers. It is which gap matters most, and everyone in the room is looking at the same evidence.

072 min

How mental model diagrams changed since 2008

The basic layout has stayed the same since the book. Young said in a later interview that the skyline looks much as it did twenty years earlier. What sits around it has changed in three ways.

The first change is in the words. Young now calls the whole diagram a mental model skyline. The summaries have grown longer, so each one carries enough detail to be read without the transcript.

The second change is thinking styles. A thinking style is a pattern in how people approach the same purpose. One person researches every option before a film, and another simply goes with a friend's choice. When those patterns show up in the data, Young marks each window with the thinking style it came from. A team can then see whether its support serves only one way of thinking. Young uses thinking styles in place of personas. A persona describes a type of person. A thinking style describes an approach, and the same person can switch styles from one day to the next.

The third change is what the diagram is for. Her Mural visualizer, released in 2026, describes teams keeping the skyline for years and using it to track how much help or harm they give people. The skyline has become a record a team returns to, not a report it reads once.

Why one diagram can hold many people

A persona tries to make a team feel for one imagined person. A mental model diagram does something different. It shows how many real people think, side by side, without asking anyone to share their feelings. Young draws this line herself. She treats cognitive empathy, understanding how someone reasons, as something that scales to many people, and emotional empathy as something that works one person at a time. That is why one skyline can hold what was heard in dozens of listening sessions, while a persona stands for one made-up composite.

082 min

Mental model diagrams vs. nearby concepts

James Kalbach groups mental model diagrams with journey maps, service blueprints and experience maps under one name: alignment diagrams, which put a person's experience and an organization's offer side by side. Among them, the mental model diagram is the one arranged by purpose rather than by time. That family resemblance causes three common mix-ups.

092 min

Using a mental model diagram to decide what to build

Back at the cinema chain, the diagram has done its first job. The team agrees that the empty tower, agreeing on a time with friends, matters more than another loyalty reward. What they do next decides whether the diagram changes the product or gets forgotten.

1. 1

   Pick gaps, not features.

   Choose one or two towers with no support or weak support, and treat each one as a problem to explore. The diagram says where to work, not what to build.

2. 2

   Check whose thinking you serve.

   If your sessions showed thinking styles, look at which styles your current support covers. A tower can be well served for people who plan ahead and empty for people who decide at the last minute.

3. 3

   Keep the out-of-scope towers visible.

   They point to partners or nearby services that could help, and they stop the team from reopening settled questions.

4. 4

   Return to it when the product changes.

   Move the support cards, not the towers. The top half stays valid until the way people think about the purpose changes.

5. 5

   Listen again when a tower looks thin.

   A tower built from two people's comments is a guess to test, not a finding.

For the cinema team, the next step is not a group booking button. It is a short round of new sessions about how friends settle on a time, so the team understands that tower well enough to design for it.

?4 questions

Questions people ask

§11 sources

Sources for mental model diagrams