What Makes Symmetry So Pleasurable to Us?

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Synchronized divers in perfect harmony. A butterfly's delicate wings. The soaring arches of a cathedral. These are examples of visuals that captivate and delight. But what makes them so appealing? The secret lies in symmetry.

Symmetry dominates the real world, especially in nature. Consider the radial patterns of starfish or flower petals, the efficient hexagonal design of honeycombs, or the intricate symmetrical shapes of snowflakes. Interestingly, asymmetry often signals danger or disease in the natural environment.

Humans, too, exhibit symmetry, at least externally (though organs like the heart and liver are asymmetrically placed). Studies on attraction reveal that both genders prefer symmetrical faces, associating them with attractiveness. This preference may stem from the belief that symmetry indicates good health, despite research showing no significant health differences between individuals with symmetrical or asymmetrical features. (Our brains might simply overinterpret minor asymmetries as signs of genetic issues.)

Our fascination with symmetry can be attributed to its familiarity. Symmetrical shapes and patterns align with the rules our brains are hardwired to recognize and appreciate effortlessly.

"Symmetry embodies order, and in our unpredictable universe, we yearn for order," notes physicist Alan Lightman in "The Accidental Universe: The World You Thought You Knew." "Discovering symmetry brings emotional joy, helping us interpret the world, much like the comfort we find in seasonal cycles and dependable friendships. Symmetry is efficiency. Symmetry is simplicity. Symmetry is grace."

A deeper reason for the delight we experience when encountering symmetrical art or an impeccably arranged display of soup cans lies in the connection between our brain's structure and nature's patterns. The neurons and synapses in our brains, along with their communication processes, evolved alongside stars and starfish. If nature thrives on symmetry, so does our mind.

"Our brain's architecture emerged from the same trial and error, the same energy laws, and the same mathematical principles that shape flowers, jellyfish, and Higgs particles," Lightman explains.

Observe the image above. What catches your eye?

If you have healthy vision and an intact brain, you'll likely see "a glowing white triangle overlapping another." However, upon closer inspection, you'll realize it's an optical illusion—no white triangle exists, just empty space framed by three Pac-Man-like shapes and a few floating V's.

This visual phenomenon, known as the Kanizsa triangle, is so compelling that your brain creates boundary lines between the triangles and enhances the brightness of the top one, despite both white areas being the same shade. Skeptical? Use your hand to block parts of the image, and watch the lines and color contrasts vanish.

What exactly is going on here?

"The brain rejects randomness," explains Mary Peterson, a psychology professor and head of the Visual Perception Laboratory at the University of Arizona. "It constructs the illusion of a brighter-than-white triangle because the alignment of the three Pac-Man shapes would seem coincidental unless obscured by a white triangle."

The triangle illusion exemplifies Gestalt psychology, a groundbreaking approach to visual perception originating in 1920s Germany. The often-misquoted Gestalt principle states: "The whole is different from the sum of its parts" (not "greater than"). In essence, if our perception merely added up visual details, we'd describe the image as "three Pac-Man shapes and some V's." But our brain is more sophisticated—it seeks order in chaos and uses rules or shortcuts to interpret the world.

Symmetry is one such shortcut. According to Peterson, we either inherit or develop "priors"—mental shortcuts—that help our brains swiftly identify objects.

Johan Wagemans, a Belgian experimental psychologist specializing in visual perception and brain organization, concurs that symmetry extends beyond external design.

"Symmetry is a key principle guiding the brain's self-organization," Wagemans notes. "The drive towards orderly and simple structures reflects symmetry in the brain's internal dynamics."

However, excessive symmetry can become monotonous. Wagemans discovered that while perfectly symmetrical designs are more appealing to the brain, they aren't necessarily more attractive. Both art beginners and connoisseurs favor works that achieve an "optimal level of stimulation," Wagemans explains. "Not overly complex, not too simplistic, neither chaotic nor overly structured." This aligns with the Japanese aesthetic principle of fukinsei, which emphasizes balance through asymmetry or irregularity in composition.