powidoki

Powidoki is a Polish term for afterimages, visual impressions that persist after the original stimulus has ceased. The word is the plural form of powidok and is used in ophthalmology, psychology, and everyday language to describe this perceptual phenomenon. Etymology traces to po- meaning “after” and widok meaning “view” or “sight.”

Mechanism and nature: Powidoki arise from the eye’s photochemical and neural responses. Prolonged exposure to bright or highly contrasted images bleaches retinal photoreceptors and triggers processing in the visual system. When the stimulus is removed, lingering neural activity can produce a perception of the image or a complementary color in the afterimage. This is often explained by opponent-process theory of color vision.

Types: Positive afterimages retain the original colors but appear faded, while negative afterimages commonly show colors complementary to the original stimulus. The latter is the more frequently observed form and illustrates how color processing in the visual system contrasts different wavelengths.

Duration and conditions: In healthy individuals, powidoki typically last from a few seconds to a couple of minutes, though they can persist longer after intense or large stimuli. They are more noticeable with bright light, high-contrast patterns, or rapid changes in gaze. While generally benign, factors such as fatigue, certain medications, or neurological conditions can influence their occurrence; persistent or accompanying symptoms should be evaluated by a clinician.

See also: Afterimage (in English), phosphenes, optical illusion.