The Cornerstone of UI Design: How Edge Shapes Influence Interaction and Information Flow

By Brady Starr, Co-Founder of Brady UX

An illustration of the Corner Dynamics Principle: Rounded corners invite interaction, while sharp corners anchor focus for information consumption.

In the fast-paced world of UI/UX design, every detail matters. From the choice of color palettes to typography, these elements guide users, influence their decisions, and shape their experiences. Yet, one often-overlooked detail has the power to subtly direct user behavior: the shape of corners.

I believe that the contours of UI elements — be they sharp or rounded — are not merely aesthetic decisions. They serve as a subtle, powerful tool to differentiate between elements meant for interaction and those designed for information consumption. I call this principle the “Corner Dynamics Principle.”

Let’s explore how this principle works and how you can use it to design with purpose.

The Case for Corners

Rounded vs. sharp edges in UI design is a topic often discussed in terms of aesthetics, but the implications go much deeper. Here’s the breakdown:

Rounded Corners: Interaction Enhancers

Rounded corners gently guide the user’s eyes, creating a sense of flow and movement. They:

• Encourage exploration: The smooth transitions of rounded corners invite users to interact, click, and explore.
• Foster approachability: Rounded shapes feel softer and friendlier, making users more inclined to engage.
• Improve cognitive processing: Studies show that rounded shapes are easier for the brain to process, reducing cognitive load during interactions.

Sharp Corners: Information Anchors

In contrast, sharper edges create a sense of structure and stability. They:

• Direct focus: Sharp corners emphasize the boundaries of an element, anchoring attention for tasks like reading or analyzing data.
• Facilitate clarity: Straight edges align with the natural flow of the content, making it easier to consume information without distraction.
• Convey seriousness: Angular shapes project professionalism and clarity, ideal for dense informational elements.

The Corner Dynamics Principle

The Corner Dynamics Principle posits that the shape of an element’s edges should reflect its intended use. This principle provides a simple framework for UI designers to consider:

1. Interactive Elements (e.g., buttons, toggles, cards):
   Use rounded corners to foster engagement.
   Example: A “Buy Now” button benefits from inviting, rounded edges, encouraging clicks.
2. Informational Elements (e.g., text boxes, static containers):
   Use straighter edges to create a sense of focus and clarity.
   Example: A news article or product description box with sharper edges keeps attention on the content.
3. Hybrid Elements (e.g., cards with both text and interaction points):
   Strike a balance by using slightly rounded corners (e.g., a radius of 4–8px) to subtly hint at interactivity while maintaining readability.

Backed by Psychology and Art

This principle isn’t arbitrary; it’s rooted in both psychological research and visual arts:

• Psychological Insights: Rounded shapes are perceived as safe and approachable, while angular shapes can feel stable but rigid. These perceptions influence user trust and engagement.
• Artistic Techniques: In painting, artists use shapes to guide the viewer’s eye. Rounded lines create flow and motion, while straight lines direct focus. UI design, in many ways, mirrors these artistic fundamentals.

Application in Real-World Design

Let’s explore how the Corner Dynamics Principle can elevate UI design:

Case Study 1: E-Commerce Platforms

On an e-commerce site, the call-to-action buttons like “Add to Cart” should use rounded corners to encourage clicks. Meanwhile, product description boxes benefit from straighter edges to ensure users stay focused on reading the details.

Case Study 2: Educational Platforms

Interactive quizzes or clickable flashcards can leverage rounded corners to make learning more engaging. Static content like course outlines or instructions, on the other hand, should use sharp edges for clarity.

Case Study 3: Mobile Apps

For navigation bars or icons designed for frequent interaction, rounded edges improve usability and approachability. Text-heavy elements like terms of service or FAQs can rely on straight edges to promote focus.

Designing with Intent

The Corner Dynamics Principle emphasizes the importance of intentionality in design. By aligning edge shapes with the purpose of UI elements, designers can subtly enhance user experiences, guiding attention where it’s needed most. This principle is more than a stylistic choice — it’s a functional decision rooted in user psychology and behavior.

A Call to Action for Designers

I challenge designers to think beyond aesthetics and embrace the functional implications of their design choices. Incorporating principles like Corner Dynamics can lead to more intuitive, effective, and user-friendly designs.

If this resonates with you, share your thoughts, examples, or feedback. Let’s start a conversation about how we can continue to elevate UI/UX design. Together, we can refine these ideas and create standards that benefit users and designers alike.

About the Author

Brady Starr is a UX designer and co-founder of Brady UX, a Baltimore-based agency that combines technical expertise, creative vision, and business acumen to deliver exceptional user experiences. Brady is passionate about crafting intuitive designs and sharing insights to inspire the next generation of designers.

Share Your Thoughts

What do you think about the Corner Dynamics Principle? Have you used similar strategies in your designs? Share your insights in the comments, or connect with me at Brady UX.