Do People Prefer Curved Lines?

Evidence from Cognitive Psychology and Implications for UX

Photo by Pawel Czerwinski on Unsplash

Do you prefer curved lines over straight ones? Research dating back from the early 1900s to today, shows that people tend to prefer curved lines over straight or angular ones. This is not limited to simple shapes but has also has been observed across a wide range of objects, including everyday artefacts and natural entities, building facades, interior rooms, as well as visual art (e.g., Dazkir & Read, 2012; Bar & Neta, 2006). Curved lines are often perceived as graceful, pliable, and gentle, while angular lines are often associated with feelings of agitation, seriousness, and even threat. This is something reflected in the world around us. From product packaging to website layouts, designers often use curved lines to create a more aesthetically pleasing experience for users. But is this preference based on personal taste, or is there something deeper at play?

Research suggests that people's preference for curves is not just a matter of personal taste, but rather a universal phenomenon in the visual domain. A meta-analysis of empirical studies on contour by Chuquichambi and colleagues (2022) found that people consistently prefer curves to angles, with a medium effect size of 0.39¹. This effect was moderated by presentation time, stimulus type, task, and expertise, indicating that contextual factors play a role in the strength of the preference.

Guggenheim museum in Bilbao (photo by me)

What is it about curved lines that makes them so popular?

One theory is that people’s liking for curves goes beyond mere preference and has its roots ingrained deeply in the way we perceive things around us. The theory argues that because nature encompasses many round or soft-edged objects like mountains, seashores, or even humans' contours- our minds have developed an innate attraction towards those structures. Angles, on the other hand, can be perceived as threatening, as jagged or sharp objects are often dangerous (Bar & Neta, 2006). Evolutionary psychologists suggest that this preference for curves may be linked to our innate preference for objects that are safe, non-threatening, and nurturing (Conway & Rehding, 2013). The preference for curves can be traced back to the fact that humans have a natural tendency to associate curves with living things, such as human bodies or plants. This preference dates back to our evolutionary past, where the ability to identify and respond quickly to living things in our environment was crucial for survival.

Another theory states that curves are simply easier on the eyes. A study by Bar and Neta (2006) found that people perceive curved shapes as more pleasant and less complex than angular shapes. This may be because curves require less cognitive processing to perceive and understand.

Even though the preference for curves is universal that doesn’t mean that they’re everyone’s cup of tea! Individual factors such as personality traits can influence preference for curves. For instance, people with higher levels of openness to experience tend to prefer more complex and unconventional shapes, including curves (Cotter & Silvia, 2017; Silvia & Barona, 2009). Different cultures and individuals have different preferences for shapes, especially when it comes to logos and designs. Collectivistic cultures tend to prefer rounded shapes, while individualistic cultures prefer angular shapes (Zhang, Feick, and Price, 2006). Self-concept and social identity also play a role in shape preference. Overall, there is evidence that shape preferences are influenced by many factors, and not solely by evolutionary motivations.

So, what does this mean for UX professionals? Understanding people's preference for curves can have important implications for design. Here are a few ways that you can incorporate this knowledge into your work:

1. Use curves to create a sense of comfort and safety. If you're designing a website or app for a healthcare provider, for example, consider using curved lines to create a more nurturing and calming experience.

2. Consider using more curved shapes for products that are designed for pleasure or enjoyment. Curved shapes are associated with positive feelings and emotions, whereas angular shapes are associated with functionality and negative emotions.

3. Be mindful of the context in which you're using curves and the type of product you’re designing for. Even though people like curved lines in general, this preference can be affected by contextual factors. In addition to this, a preference for curvature, doesn’t mean people dislike angular designs!

4. Know your user. You knew it would come down to this, if you read this newsletter regularly! There are no one size fits all approaches in UX. By conducting user research and understanding your users, you can choose more appropriate designs.

Understanding people's preference for curves is important in design, as it can have a significant impact on user experience. Research has shown that people tend to prefer curves over angular shapes, likely due to our innate attraction towards safe, non-threatening, and nurturing objects. However, individual factors such as personality, culture, and context can also influence shape preference. By incorporating knowledge of user preferences into design, we can create more visually appealing and effective products.

1. Effect sizes are statistical measures that quantify the strength and magnitude of the relationship or difference between two or more variables in a study. They are used to determine the practical significance of a finding beyond statistical significance, which only indicates whether the result is likely to have occurred by chance or not. A medium effect size suggests that the relationship or difference between two variables is moderately strong and can be observed with reasonable consistency across different studies.