Incremental modular design breaks down big problems and large-scale projects into small, manageable modules. Yet, the method helps us to have the larger goal in mind. When we engage in large projects it’s important to always have the bigger goal in mind. However, incremental modular design recognizes that we can't define the clear path to take from the very beginning of a large project.
Incremental modular design allows people to:
Work on smaller projects and in shorter spans.
Analyze and evaluate the first result they create and then decide whether they are going in the right direction to find the solution to the bigger problem.
Learn and get smarter as they work their way towards the goal.
Be flexible and pivot when conditions, technologies, or situations change.
The grandfather of User Experience design, Don Norman, explains what incremental modular design is right here in this video.
This approach combines concepts from agile development, object-oriented programming and incrementalism to help teams work on large complex problems without getting stuck with large complicated projects that might become irrelevant by the time they are implemented.
In incremental modular design people add one module after the other just as we add one Lego brick after the other while ensuring our first Lego bricks are solidly placed in the location we want. Only after evaluating the first steps we can go on to take the next steps in the best possible way, and we always have the complex drawing of our end Lego castle to guide each step we plan and take.
Define the goals: Get the funders, the communities, and all the stakeholders to agree on the goals of the large project.
Democratize design: Involve the people we are designing for. They will identify their problems and needs and help us develop solutions.
The minimum viable project: Deliver the solution in small steps, analyze the results, and decide the next course of action based on the analysis.
Independent modules: Develop modules with clearly defined input and output requirements but hidden internal workings. Teams must be able to change how the modules work internally without affecting the inputs and outputs.
We can adapt to different social and technical conditions when we have a clear goal and use multiple smaller projects divided into standalone modules.
© Interaction Design Foundation, CC BY-SA 4.0
Incremental modular design offers flexibility with:
Requirements: As the team delivers, tests and learns from each incremental step, it can adapt and course-correct easily and even tweak the requirements if needed.
Module replacement: Since modules are independent, the team can update any module without harm to the system as long as the input and output requirements remain the same.
Local adaptation: It doesn’t matter how the module works internally. So, the team can change the internal workings to suit local cultures.
Incremental modular design is an applied and practical approach to incrementalism with the added benefit of offering a roadmap for future work. Good UX relies on a feedback loop of user research, testing, ideation and empathy. With larger projects, getting user feedback and trying new design ideas is far riskier, so stakeholders often hesitate to fund purely incremental projects. An incremental modular design approach makes it easier to secure stakeholder buy-in for large, flexible projects.
User experience designers and UX researchers evaluate each step independently with user testing. Then they can gauge whether their intervention is going in the right direction.
This approach is a great fit for large, non-digital projects. For a digital product, a complete redesign can be relatively simple to implement. Larger projects based on physical infrastructure, electrical grids or transit systems are difficult to change all at once. For example, an incremental modular approach might focus on one transit station or one block of a power grid. After evaluating the solution, designers can decide if the module was successful enough to be scaled up or repeated.
Incremental modular design allows teams to tackle large problems with fewer risks. Small teams have an advantage when it comes to taking risks. They can develop modules that would be too risky for larger, more complex products. This allows them to explore more solutions.
Identifying and solving small issues is a part of the bigger picture. This helps designers tackle the biggest problems one step at a time.
In design of technology the incremental modular design method allows us to continuously add new modules, functions and improve existing features. We can develop and test every module on its own before integration. This allows for easier maintenance and a more scalable solution. Each module builds on the other to solve large-scale problems, piece by piece.
Would you like to learn more about solving large-scale problems by using the incremental modular design approach, then go ahead and take our course Design for a Better World with Don Norman.
Norman, Donald A. Design for a Better World: Meaningful, Sustainable, Humanity Centered. Cambridge, MA, MA: The MIT Press, 2023.
Read more articles and essays by Don Norman on JND.org.
Here’s the entire UX literature on Incremental Modular Design by the Interaction Design Foundation, collated in one place:
