The Dia Art Foundation in a New York conference on the theme of vision and visuality in 1988 was published later that year as the second volume in Dia’s Discussions in Contemporary Culture.

In hindsight, the Hal Foster (ed.) Vision and Visuality, as the book came to be called, may be seen as the moment when the visual turn – or as it is sometimes called, the ‘pictorial turn’ in western culture was recognized; a moment when the assumption of the image as a natural sign, a straightforward analogue of its object, was undermined.

This challenged the entrenched way of understanding visuality in western culture since Plato. Plato's Cratylus distinguished between words as conventional signs and images as their natural counterparts. For Plato, there were two ways of representing a man, either by saying his name or by drawing his portrait. Whereas words were taken to be arbitrary signifiers without any necessary relation to what they signified, images were understood to be tied by natural forces to what they resembled, iconic analogues of their objects.

Mimesis of the real was assumed to be better served by vision than by any other sense. Although for some commentators the conventionality of words was taken to betoken their superiority as expressions of human creativity and imagination, for others images had the advantage because of their ability to transcend specific cultural contexts and show ostensively what could not easily be said or merely described.

W.J.T. Mitchell’s (1986) summary of this time-honored position in his Iconology: Image, Text, Ideology is this:

The naturalness of the image makes it a universal means of communication that provides a direct, unmediated, and accurate representation of things, rather than an indirect, unreliable report about things. The legal distinction between eyewitness evidence and hearsay, or between a photograph of a crime and a verbal account of a crime, rests on this assumption that the natural and visible sign is inherently more credible than the verbal report. The fact that the natural sign can be decoded by lesser beings (savages, children, illiterates, and animals) becomes, in this context, an argument for the greater epistemological power of imagery and its universality as a means of communication.

Situated firmly in the world of convention can be interpreted as images embedded in language, socio-cultural mediation, or technological virtualization. Images can no longer be seen as natural, unmediated signs, which can shed all their cultural encoding.