Why do we prefer organic lines?

Contour bias is a straightforward principle and something we use everyday, but usually unconsciously.

Humans have an innate tendency to favour objects with curved contours over objects with sharp angles or points. Research¹ shows that when our brains recognise sharp angles, it activates the amygdala; a region of the brain associated with processing fear and emotion. When brain activity is measured, the amygdala activation is directly proportional to the degree of sharpness in an object.

Studies² show we strongly prefer rounded objects over angular ones. Take lots of technology products, especially anything Apple designs: precise bezels on hardware, rounded corners and soft transitions throughout the software. Knowing that we prefer or respond more positively to contoured objects, Apple is making sure we feel comfortable when using their products.

But this doesn’t mean designers should make everything rounded. In fact, quite the opposite is true. Angular and pointy objects can be used to provoke thought and engage our attention — just think of traffic signs that intend to warn us: they’ve been deliberately designed as triangles.

It’s worth pointing out that contour bias is certainly true for emotionally neutral objects (a website, a mobile phone, or a car), but when an object carries emotion (like a knife or baby’s face), that emotion tends to override the effect of contour bias.

As designers, the lessons we take from the idea of contour bias are to consider using contoured forms or shapes to make positive first impressions, and carry an approachable tone of voice. Conversely, we’re able to recognise when it might be more appropriate to use angular and sharp shapes to attract attention to something and provoke an instant response.

These ideas can be applied to the whole spectrum of design, whether digital design, product design, or architecture.