Dark adaptation is the physiological process where the eyes increase their sensitivity to light after moving from a bright to a dimly lit environment. This adjustment occurs as vision shifts from being primarily dependent on cones to being dependent on the more light-sensitive rods. The process is not immediate and involves a delay of several minutes for the rods to become fully active.

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Rods and cones are two types of photoreceptors in the retina with distinct locations and functions. Cones are concentrated in the fovea and are responsible for high-acuity color vision in bright light. In contrast, rods are distributed throughout the rest of the retina, enabling vision in low-light conditions and the perception of peripheral movement, though they lack the ability to see color and fine details.

Comparison of Rods and Cones

Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020, April 22). Psychology (2nd ed.). OpenStax. https://openstax.org/books/psychology-2e/pages/1-introduction

OpenStax Psychology (2nd ed.) Textbook

Dark Adaptation

A common example illustrating the different sensitivities of rods and cones is entering a dark movie theater from a bright lobby. At first, it is hard to see because vision relies on cones, which require bright light. After a few minutes of dark adaptation, the highly sensitive rods become active, allowing one to see in the dim environment.

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