Mental Models for Product Design

Use mental models: simple explanations of how something in the world works. Like supply and demand, which helps us understand the economy, or the?Pareto Principle, which helps us understand cause and effect.

To get you started, I’ve put together the top three of my favorite mental models that I use daily to build a product. They’ll help you solve problems, make decisions, and communicate ideas.

1. First principles

Do you need an innovative solution to a complex problem? Try approaching the problem from the first principles.

To do this, take your problem and:

1. Break it down into its fundamental parts
2. Reconfigure those parts to build a solution

This is a popular technique in user research where a researcher digs deeper by repeatedly asking “why” questions. It enables you to discover the root causes of problems. Of course, you don’t have to stop at five, but it’s generally enough to discover a first principle.

How to use it

A form of disciplined questioning that enables critical thinking. There are six types of questions you can ask to dig deeper for the fundamental truth:

1. Clarification — “What do you mean by…?”
2. Probing assumptions — “What could we assume instead?”
3. Probing reasons/evidence — “Why do you think this is true?”
4. Implications and consequences — “What effect would that have?”
5. Different viewpoints — “What would be an alternative?”
6. Questioning the original question — “What was the point of this question?”

In Practice

2. Inversion

Are you solving for only the best-case scenario? Try inversion to get a 360-degree view of your problem. To do this, instead of thinking of ideal solutions, think of bad solutions then ask yourself, “How might we avoid these?”

How to use it

You can then invert your thinking about the problem or a solution. To do that, follow these steps:

1. Ask yourself: What would be the worst decision/solution in this situation?
2. Ask yourself: Why would it be bad? Write those reasons down.
3. Try to come up with a good decision/solution, now by looking at the reasons that would make a bad decision.

In Practice

We did this with our Customer Experience team, which handles all of the customer support. Before the project started, we met with two of our top-tier agents, and they helped us brainstorm all the ways in which the feature could potentially go wrong for our users. They helped us round out our view of the problem, instead of locking into an early idea.

3. Abstraction laddering

It helps with defining a problem that you need to solve more clearly. It helps you to move beyond an initial problem statement. This tool provides you with the ability to ask the right questions to move up and down the ladder.

Move up to expand the scope, to “see the forest for the trees”. Move down to develop concrete solutions.

How to use it

1. Start with an initial problem statement in the middle of the ladder.
2. Ask “why” questions to get more abstract problem statements. This can help you frame the problem differently.
3. Ask “how” questions to step toward a more concrete statement or solution. This helps you come up with different problem statements than the one you started with. It enables you to find more innovative solutions.

In Practice

1. Start with your original problem statement: Design a better can opener
2. Then ask “how” questions to get to more concrete statements. How might we design a better can opener? → Make it more appealing. Paint it red and add a bow!
3. You can also ask “why” questions to get more abstract statements. Why might someone need a can opener? → To get soup out of a can
4. Now ask “how” from a higher level How might we design a better way to get soup out of a can → We could redesign the top of the can itself to be a pop top

Reference :

1. https://fs.blog/first-principles/
2. https://www.autodesk.com/industry/manufacturing/resources/mechanical-engineer/abstraction-laddering
3. https://jamesclear.com/inversion