Purkinje effect

Purkinje effect is a phenomenon in human visual perception where, under low light conditions, the peak sensitivity of the human eye shifts towards the blue end of the color spectrum. This effect is named after the Czech anatomist Jan Evangelista Purkyně, who first documented the shift in 1825.

Overview

The Purkinje effect occurs as the level of ambient light decreases, such as during twilight or in a darkened room. As the light level decreases, the cone cells in the human eye, which are responsible for color vision and are most sensitive to green light, become less active. Meanwhile, the rod cells, which are more sensitive to blue and green light and are responsible for peripheral and night vision, become more active. This shift in sensitivity is what causes the Purkinje effect.

Causes

The Purkinje effect is caused by the differing sensitivities of rod and cone cells in the human eye. Cone cells, which are responsible for color vision, are most sensitive to green light. However, as the level of ambient light decreases, these cells become less active. On the other hand, rod cells, which are responsible for peripheral and night vision, are more sensitive to blue and green light. As the light level decreases, these cells become more active, causing the perceived color of objects to shift towards the blue end of the spectrum.

Effects

The Purkinje effect can have a significant impact on visual perception, particularly in low light conditions. For example, it can cause objects that appear green in bright light to appear blue in dim light. This can have practical implications in a variety of fields, including astronomy, photography, and aviation.

See also

• Scotopic vision
• Photopic vision
• Mesopic vision
• Color vision

References

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