Seeing Symmetry: How Brains Can Find Order in Visual Disorder by Gianna Eisen

 Seeing Symmetry: How Brains Can Find Order in Visual Disorder by Gianna Eisen

When looking at a butterfly, a tree, or even a human face, you do not consciously know that it is symmetrical, but your brain does. In the 2009 study, The Role of Vertical Mirror Symmetry in Visual Shape Detection, by Machilsen, Pauwels, and Wagemans, they explored this automatic process. By applying arrays of small visual elements, or Gabor arrays, they found that individuals were better at identifying shapes when the patterns were vertically symmetrical, even if noise was added in an attempt to obscure them.

Their results showed that symmetry is not just something individuals can spot from plain sight, but a fundamental cue that human brains use to organize information that is presented. In a cluttered scene, symmetry can help the visual cortex to quickly group elements of a system together into shapes. This principle can trace back to the Gestalt psychologists’ idea that the whole is greater than the sum of its parts. Showing that when brains detect balance, it is interpreted as structured and significant

So why does orientation matter? While Machilsen et al. revealed how symmetry enhances detection, newer research from another lab has expanded this idea. A 2024 study published in the Journal of Vision, The role of vertical mirror symmetry in visual shape detection by Makin, Rampone, and Bertamini, examines how the brain processes different axes of reflection symmetry — specifically, vertical versus horizontal. In this experiment, participants were shown clouds of dots that contained both target and distractor patterns. They were asked to focus on one type of symmetry while ignoring another, for example, they were told to focus on vertical while ignoring horizontal. Using an EEG, the researchers were able to measure a brain signal called the Sustained Posterior Negativity (SPN), which is linked to symmetry detection. They found brain processes symmetry in axis-specific channels, showing that when people attended to vertical symmetry, horizontal symmetry in the distractor patterns didn’t interfere, and vice versa. This shows that our brains can handle different types of symmetry separately, like there are dedicated pathways for each orientation.

Both studies highlight how symmetry guides our perception of order in the visual cortex of the brain, but they focus on different aspects of the process. Machilsen et al. (2009) demonstrated that symmetry serves as an influential cue for detecting shapes amid visual noise; our brains use symmetry to group features into meaningful wholes. Whereas Makin et al. (2024) showed how the brain processes this information, revealing that vertical and horizontal symmetries activate separate neural pathways, with little cross-interference. Together, these studies can deepen our understanding of visual organization. Showing that symmetry can help us recognize objects faster, and the brain’s ability to filter/separate symmetrical axes may explain why we can easily detect structure in complex patterns.

However, these insights extend beyond neuroscience labs, in daily life, symmetry influences our preferences, from fashion and architecture to human faces we find attractive. Understanding how the brain processes symmetry informs artificial intelligence and computer vision systems, which can aim to mimic our visual processing abilities. If AI systems can learn to detect symmetry as efficiently as humans do, they might improve at recognizing objects in noisy environments, like identifying faces in poor lighting or analyzing satellite images. This is something used daily with the use of Face ID. Similarly, knowing that our brains can separate symmetry by either axis could help engineers or architects avoid confusion in visual displays by aligning features with consistent orientations.

Both the 2009 and 2024 studies remind us that our perception of the world isn’t random, but is guided by deeper biological principles that favor balance, order, and organization. As Gestalt theorists proposed a century ago, the mind naturally seeks patterns that make sense of chaos. Today’s neuroscience findings confirm that symmetry isn’t just beautiful, but essential to how we see and understand the world.

Works Cited:

Makin ADJ, Rampone G, Bertamini M. The brain does not process horizontal reflection when attending to vertical reflection, and vice versa. J Vis. 2024 Mar 1;24(3):1. doi: 10.1167/jov.24.3.1. PMID: 38427362; PMCID: PMC10913937.

Machilsen, B., Pauwels, M., & Wagemans, J. (2009). The role of vertical mirror symmetry in visual shape detection. Journal of Vision, 9(12):11, 1–11, http://journalofvision.org/9/12/11/, doi:10.1167/9.12.11.