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What is the Purkinje Effect?

Discovered by Jan Evangelista Purkinje, the Purkinje Effect was initially observed because of the changing colors of Jan’s favorite flower in his outdoor strolls. His simple speculations revolutionized the way we understand our vision now. 

The Purkinje Effect describes the color-changing phenomenon in our vision when we’re in varying light conditions wherein color contrast changes for our eyes to adapt. 

The Science Behind the Purkinje Effect

The Purkinje Effect is a phenomenon that describes how colors appear darker or different under different illuminations. Under varying levels of lightness and darkness, the colors of an object change alongside it. 

The reason behind the Purkinje Effect is how our eyes can adapt to darkness or low levels of light, and when they adjust – the luminance sensitivity of our eye moves to the blue end of the color range. With that, the red hues of a rose will deepen as illumination lessens.

Additionally, the Purkinje Effect tackles how color contrast levels also depend on the amount of light present. A well-used example to demonstrate this effect is the geranium flowers and the leaves that surround them. In direct, beaming sunlight, the geranium flower’s red will become more vivid against the muted green hues of the leaves. The situation changes when dusk hits and the sun dims, turning the dull greens and blues of the leaves into a more bold color while the reds of the flower becoming a darker shade. (Source: John Frisby

Although most studies that describe the Purkinje Effect come from a human perspective, the Purkinje Effect also exists in the eyes of many animals to adapt to the vision changes light and dark bring.  (Source: The Journal of Physiology

The science behind the Purkinje Effect is in the cone and rod cells found in the retinas of our eyes. The estimated 4.5 million cone cells in our retina make us see color. The cone cells are most responsive to yellow light. Meanwhile, the 90 million rod cells that reside in our retina work in darkness, but they cannot discern various colors, making our vision almost see in grayscale when it’s dark. They are most sensitive to the end of the color spectrum, where one sees the greens and the blues.

As light decreases, the rods slowly gain control over the cones, gradually changing our perception of color to the blue-green end of the color spectrum. (Source: Perpetual Enigma

Who Discovered the Purkinje Effect?

Jan Evangelista Purkinje, a groundbreaker in physiology, first observed the Purkinje Effect. Without his contributions in the fields of histology, pharmacology, and embryology, our understanding of the functions within our brain, heart, and eyes would be different. (Source: Britannica

He worked at the University of Prague as a physiology professor, which became a catalyst in the Purkinje Effect’s discovery. Because of his habit of walking outdoors before the sun was at its brightest. In his walks, he observed that his favorite flowers, which hues shined so bold in direct daylight, were a much darker color when compared to the color of the leaves when darkness came.

His simple observation birthed the Purkinje Effect. He concluded that human beings have two distinguished systems for vision. One is used in lighter settings, with the other system utilized in the decrease of light. (Source: Perpetual Enigma

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