What is Perception?
Written by David Kim-Shoemaker
Edited by Claudia Reines
Drawings do not actually exist in three dimensions. Everyone consciously knows this, yet our eyes sometimes do not seem to realize it. From drivers making wrong turns into murals to software such as Blendr, “tricking” our brains, this is also an integral part of art and science [1]. But why is this? How do artists capture our visible world with just pencil and paper?
It is first important to understand how sight works. The human eye is split into several different parts, but light first enters through the cornea. From there, an image is projected on the back of the retina, where rods and cones detect light and color, respectively [2]. This information is then relayed to the occipital lobe, where it is “interpreted” into what we call sight. Resultingly, our brains do not really have an idea of what is 3D versus 2D beyond the image our retina observes. So where does the third dimension come from?
Photos by EllaRose Sherman (eks92@cornell.edu), featuring Chloe Scarindo, taken at the Herbert F. Johnson Museum of Art.
Part of it is from the fact that we have two eyes facing the same direction coming from two different directions in what is called binocular vision. The disparity between the left and right eye allows for differences in the horizontal position of whatever we are looking at to form a concept of distance [3]. This, along with cues such as shading, texture gradients, and motion parallax (the way objects farther away appear slower) allows for our eyes to notice minute details in position.
These innate traits have been manipulated to great extent by artists. Around the time of the Renaissance, these started to become integrated into paintings and became so developed that they would receive different names depending on what was manipulated: Chiaroscuro (the use of strong light-dark contrasts), cangiante (darker colors being used to show shading), sfumato (intentional blurring to replicate what would be out-of-focus), and many more [4].
A depiction of the Delphic Sibyl on the Sistine Chapel ceiling, by Michelangelo. Here, it may be observed that shading is achieved with different hues of the colors themselves, rather than the presence of black coloring. Photo from https://www.michelangelo.org/. Curated by David Kim-Shoemaker (djk323@cornell.edu).
Renaissance artists didn’t just happen to “figure out” how to make these paintings. Investigations into Leonardo da Vinci’s notebooks revealed that he had experimented with and studied the human eye extensively. He dissected bird eyes and devoted a not insignificant portion of his work to determining how the eye saw the cone of a candle light. The interactions of shadows, colors, and the way images were projected into eye were all recorded and applied to his work in a way that resulted in the uncanny realism he is known for today [5].
Sight may be the “trickiest” sense in that it is perpetually present, yet its mechanisms are so hidden. What we take for granted is a result of millions of years of evolution that we ourselves do not entirely understand. At its core though, art is a study of what it means to be human. A painting may both deceive our eyes and capture our hearts, provoking both the scientist and the philosopher in us all.
David Kim-Shoemaker ‘29 is in the College of Agriculture and Life Sciences. He can be reached at djk323@cornell.edu.
Sources:
[1] J. Torchinsky, “Real-Life Wile E. Coyote Drives Fiat Smack Into Painting Of Tunnel,” Jalopnik, Mar. 18, 2016. https://www.jalopnik.com/real-life-wile-e-coyote-drives-fiat-smack-into-paintin-1765745078/ (accessed Nov. 04, 2025).
[2] D. Purves et al., “Anatomical Distribution of Rods and Cones,” Nih.gov, 2012. https://www.ncbi.nlm.nih.gov/books/NBK10848/
[3] N. Qian, “Binocular Disparity and the Perception of Depth,” Neuron, vol. 18, no. 3, pp. 359–368, Mar. 1997, doi: https://doi.org/10.1016/s0896-6273(00)81238-6.
[4] “The Four Canonical Painting Modes and Techniques of the Renaissance,” artium.co. https://artium.co/en/node/126
[5] “A new perspective: Leonardo’s view on optics,” Google Arts & Culture. https://artsandculture.google.com/story/a-new-perspective-leonardo%E2%80%99s-view-on-optics-the-british-library/ggUB21K_Zzw1JQ?hl=en
