Symmetry – the Science

Symmetry home picSymmetry can be defined as “agreement in dimensions, due proportion, arrangement” or correct or pleasing proportion of the parts of a thing. In everyday language, symmetry refers to a sense of harmonious and beautiful proportion and balance. Symmetry in design has been used for millennia – is there a reason artists and designers have relied upon it, and how does that translate into a home’s curb appeal? First let’s take a look at what science shows us.

Scientists have been intrigued by the use of symmetry and have studied its effect on both human and other primate brains. It has been theorized that an evolutionary bias toward symmetry exists. This may be due to the fact that in biology symmetrical bodies seem to be the best designed for procreation. There have been studies that have demonstrated that human faces considered to be attractive are also quite symmetrical.

However, humans aren’t the only creatures who are inherently balanced. Scientists have found that The Golden Mean, a closely mirroring ratio of 1:1.61 occurs again and again in nature. Human bodies meet these proportions, but so do the curvature of seashells, the formation of clouds, and even the circular pattern of the universe.

Do humans really react to the symmetry found in nature and is that why we use it so extensively in design? Dr. Christopher Tyler, a visual psychophysicist of Smith Kettlewell Eye Institute, has done research using functional magnetic resonance imaging (fMRI) that has shown that the brain reacts to symmetry in the occipital lobe, the primary part of the brain that reacts to visual stimuli. This research indicates that human symmetry processing is hard-wired. In a matter of less than .05 of a second, humans instinctively scan a visual object for symmetrical qualities.

Follow up studies by Yuka Sasaki and others tested whether the fMRI activity found in Tyler’s studies correlated with the “perception” of symmetry. An excellent correlation was found, especially in higher-tier visual cortical areas. The response was highly correlated with the psychophysical perception of symmetry. The study also showed weaker symmetry responses in analogous regions of macaque visual cortex, suggesting that while the underlying neural mechanisms are also present in nonhuman primates but visual symmetry is specifically enhanced in the human brain.

A lot of science stuff to digest, but these studies show that there is evidence that human brains react positively to visual symmetry. We’ll continue to explore symmetry in curb appeal in future posts – with more on design and less on the occipital lobe!