As designers, we often gravitate towards curved edges over sharp ones, but why? Is it just an intuitive choice, something that feels more inviting? Or is there something more to it? After all, it’s not just about looking nice, it’s about what makes users engage.

Interestingly, recent studies combining eye-tracking technology, digital questionnaires, and subjective data have revealed some interesting insights about button shapes. While there’s no one-size-fits-all, evidence suggests that users generally prefer buttons with a moderate corner radius over those with sharp edges. In fact, research shows that buttons with fully sharp edges were the least favoured in the study by Gleichauf et al., 2025.

The Impact of Curves on Engagement

One particularly interesting study from Biswas et al., 2024 shows that curved buttons don’t just look more appealing—they increase engagement. Eye-tracking data revealed that users looked at curved buttons 28.6% longer than those with sharp edges, and their gaze returned to those buttons 61.8% more often. So, in conclusion, curved buttons seem to be far more effective at capturing, and keeping user attention.

So, why does this happen? It has a lot to do with the way our brains process shapes and emotions. Studies show that sharp visual cues are often interpreted as danger, which triggers the amygdala—the part of the brain responsible for processing fear and threat. This response, driven by the fight-or-flight mechanism, is something we don’t even have to consciously register. Essentially, sharp angles can subconsciously make us feel uneasy or on edge (possibly rooted in early human survival instincts, when sharp, pointed objects signalled danger), which affects how we interact with the interface.

Curves = Comfort

On the other hand, curves are often associated with softness and safety. Curved shapes have been shown to produce positive emotional responses, which is why they are commonly used in design to create a welcoming, friendly feel. It’s why many of our favourite apps and websites feature rounded buttons. We naturally feel more comfortable with them, which leads to better overall engagement and usability. Material guidelines originally featured sharper edges in its first iteration, but shifted toward more rounded corners in Material 2, and has now fully embraced rounded elements in Material 3. Apple has always favoured softer corners across its interface.

But how curved is the optimum? Results from the study by Gleichauf et al., 2025. found that buttons with moderate radii—enough to break the sharp edges but not so much that they become fully circular—strike the perfect balance. Maybe too much curvature could feel overly playful, which may not be appropriate depending on the context, while too little creates that sharp, unsettling feeling.

What This Means for UX/UI Design

For UX/UI designers, understanding how button shape impacts user psychology is essential for creating effective and engaging experiences. If you’re designing a call-to-action button or any interactive element, consider opting for rounded edges. Not only will they likely resonate better with users on an emotional level, but the science shows they are also more effective at capturing attention and encouraging interaction.



Sources
Gleichauf, K.; Wagner-Hartl, V.; Ackner, G.J.; Pfeffer, S. Understanding Visual Attention to Button Design Utilizing Eye-Tracking: An Experimental Investigation. Appl. Syst. Innov. 2025, 8, 27. https://doi.org/10.3390/asi8020027

Biswas, D.; Abell, A.; Chacko, R. Curvy Digital Marketing Designs: Virtual Elements with Rounded Shapes Enhance Online Click-Through Rates. J. Consum. Res. 2024, 51 (3), 552–570. https://doi.org/10.1093/jcr/ucad078