Cognitive Load in Code Reviews: How to Write PRs Your Teammates Can Actually Read

Code reviews are one of the most important practices in modern software development. They help teams catch bugs early, maintain coding standards, and share knowledge across developers. But there’s one hidden factor that determines whether code reviews are smooth and productive or frustrating and slow: cognitive load.

Cognitive load refers to the amount of mental effort required to process and understand information. In the context of software development, every Pull Request (PR) you open requires your teammates to spend mental energy figuring out what you did, why you did it, and whether the change makes sense.

If your PR is confusing, overly large, or poorly explained, you’re not just making life harder for your reviewers you’re slowing down the entire team. Clear and readable PRs reduce mental strain, improve collaboration, and lead to better, higher-quality code.

This article explores how cognitive load affects code reviews, why it matters, and how you can write PRs that your teammates can actually read without pulling their hair out.

Understanding Cognitive Load

The concept of cognitive load comes from psychology and education research. It describes the limits of our working memory the part of our brain that holds and processes information temporarily. When cognitive load is too high, our brains get overwhelmed, and we stop learning or understanding effectively.

There are three types of cognitive load:

1. Intrinsic Cognitive Load

This is the mental effort required to understand the material itself. In code reviews, the complexity of the code change itself contributes to intrinsic load.

Example: Reviewing a simple typo fix has low intrinsic load. But reviewing a new distributed caching system with multiple moving parts has high intrinsic load.

2. Extraneous Cognitive Load

This is the unnecessary mental effort caused by how information is presented. It doesn’t come from the content itself but from poor communication.

Example: A PR with no description, unclear commit messages, or a messy diff creates extraneous load. The reviewer wastes energy trying to figure out what’s happening instead of focusing on the code.

3. Germane Cognitive Load

This is the mental effort that contributes positively to understanding. In code reviews, it’s the effort that helps a reviewer learn something new, like understanding a design pattern or learning a new library.

Example: A PR that explains why a certain architecture was chosen increases germane load, but in a useful way. The reviewer invests effort, but it builds knowledge.

Key takeaway: As an author of PRs, you can’t eliminate intrinsic load (some code is just complex), but you can reduce extraneous load and increase germane load with good practices.

The Impact of High Cognitive Load in Code Reviews

When cognitive load is too high during a code review, several negative outcomes can happen:

- Slower reviews: Reviewers take longer to approve because they’re trying to untangle what’s going on.
- Missed issues: Overwhelmed reviewers may overlook bugs, edge cases, or security flaws.
- Frustration: Reviewers feel annoyed, which discourages collaboration and feedback.
- Lower quality code: If reviews are rushed just to reduce backlog, important problems may slip into production.

Real-World Scenarios

• A junior developer opens a PR with 2,000 lines of changes and no explanation. Reviewers spend hours guessing the context, leading to frustration and delayed approval.
• A senior engineer submits a PR with a complex algorithm but adds comments explaining the logic. Even though the intrinsic load is high, reviewers feel guided and learn something new.
• A team member merges large PRs without review because “nobody has time to read them.” Later, the team spends weeks debugging an issue that could have been caught early.

The lesson: High cognitive load in reviews doesn’t just affect one person it impacts the whole team’s productivity and morale.

Best Practices for Writing Effective PRs

Here’s how to make your PRs less painful and more productive for your teammates:

1. Write Clear and Concise Titles

- Bad: fixes
- Good: Fix typo in login error message
- Better: Fix typo in login error message that prevented proper logging of failed attempts

2. Provide Context in Descriptions

• Explain why the change is needed, not just what was changed.
• Link to tickets, issues, or design docs for more detail.

Example: “This PR introduces caching for the user profile service. Without caching, frequent requests caused database strain. The cache stores user profiles for 15 minutes to reduce DB load.”

3. Break Down Large Changes

• A PR with 50 small commits is overwhelming.
• Instead, create multiple smaller PRs: e.g., one for refactoring, one for new features, one for tests.

4. Use Visual Aids

• Diagrams, screenshots, or even ASCII drawings can make complex logic clearer.

Example: When changing UI, include a before/after screenshot.

5. Comment Effectively

• Add comments in tricky code sections explaining why you chose that approach.
• Avoid over-commenting obvious code; focus on clarifying complexity .

6. Follow Consistent Standards

• Stick to agreed-upon coding conventions.
• Consistency reduces cognitive load because reviewers don’t have to mentally parse different styles.

Tools and Techniques to Aid Code Reviews

Technology can help reduce unnecessary mental effort:

Code Review Platforms

- GitHub / GitLab / Bitbucket: Provide inline comments, file change filters, and review assignment.
- Phabricator: Offers structured review workflows.

Documentation Tools

• Use Markdown templates for PR descriptions.
• Include checklists for reviewers (tests added, docs updated, etc.).

Techniques

- Pair programming: Reduces the need for long explanations later.
- PR templates: Standardize descriptions so reviewers always know where to look for context.
- Automated checks: Linting, formatting, and CI/CD pipelines reduce trivial comments.

Encouraging Team Collaboration and Feedback

Code reviews aren’t just about catching bugs they’re about building trust and improving team knowledge.

Tips for Better Team Dynamics

- Encourage open communication: Make it safe for reviewers to ask questions.
- Focus on the code, not the coder: Critique the work, not the person.
- Give constructive feedback: Instead of “This is wrong,” say “Could we simplify this loop by using a map?”
- Be open to feedback: If someone suggests an improvement, don’t take it personally.

Cultivating a Feedback Culture

• Celebrate well-written PRs as examples for the team.
• Rotate reviewers to spread knowledge.
• Encourage junior developers to review PRs it’s a great way to learn.

Call To Action:

• Next time you open a PR, ask yourself: am I adding clarity, or adding cognitive load? Start small, and your teammates will thank you.
• Want to level up your PR game? Try applying even one of these practices in your next review and see the difference.
• Clear PRs don’t just ship faster they make teams stronger. What’s one change you’ll make in your next PR?

Conclusion

Cognitive load is invisible, but its effects are very real. Every PR you open either lightens or adds to your teammates’ mental burden. By writing PRs that are clear, concise, and well-documented, you make life easier for your team and you also improve the overall quality of the codebase.

Key takeaways:

• Reduce extraneous load by writing clear descriptions, breaking down PRs, and adding context.
• Encourage germane load by explaining design decisions and fostering learning.
• Use tools, templates, and standards to create consistency.
• Build a culture of constructive feedback and collaboration.

Ultimately, the goal of a PR is not just to merge code, but to build understanding. By managing cognitive load, you ensure your teammates can actually read, review, and improve your code making your team faster, happier, and more effective.