Persistence of vision does not explain movies, despite what you were taught
Films run at 24 still frames a second, a standard fixed when talking pictures arrived in the late 1920s. The popular explanation, that each picture lingers on the retina, is not scientifically valid. Researchers now credit the brain's own processing, with labels like flicker fusion and the phi phenomenon, and admit none fully captures it.
An image is any visual representation, from a sculpture to a photograph to a pie chart. Some are fleeting, like a reflection in a mirror or the picture inside a camera obscura; others are fixed on paper or cloth. A grayscale photograph still counts even though it ignores colour and uses only the eye's sensitivity to brightness. Other tools produce images of things the eye can never see directly, as microscopes, telescopes, X-rays and MRI scanners convert invisible signals into pictures.
Making pictures appears to be nearly universal. Rock art, including cave paintings, carvings and giant ground drawings, turns up on every inhabited continent from at least the Paleolithic, perhaps for record-keeping, ritual or communication. Early writing systems, including Egyptian hieroglyphs and, in some respects, the Roman alphabet, grew partly out of pictures.
The philosopher Charles Sanders Peirce offered a useful way to think about what images mean. An icon resembles its subject, as a portrait does. An index is physically connected to what it signals, the way smoke points to fire. A symbol carries a meaning set by convention: red can mean rage, beauty or a political party. The Statue of Liberty is all three at once. It resembles a woman modelled on the Roman goddess Libertas, it stands for New York and for immigration through nearby Ellis Island, and it symbolizes freedom.
Images have long attracted suspicion. In the Republic, Plato argued that the world we perceive is already an imperfect copy of higher forms, so art is a copy of a copy, likely to mislead and even corrupt. Similar worries grew with photography from the mid-19th century. Late 20th-century critics such as John Berger in Ways of Seeing and Susan Sontag in On Photography examined the assumptions about power, race, sex and class hidden inside even realistic pictures.
Source: Image
