This chapter's main focus is the very first half second or so after a
visual stimulus is presented to a subject. There is some sort of visual
persistence beyond the duration of the physically present stimulus.
Neisser ( 1967) was the first to apply the term icon or iconic memory
to visual persistence. His initial description of the icon as a transient
visual memory is as follows:

. . . visual input can be briefly stored in some medium which is subject
to very rapid decay. Before it has decayed, information can be read
from this medium just as if the stimulus were still active. We can be
equally certain that this storage is in some sense a "visual image." (pp.
18 - 19 )

The development of the notion of iconic memory offers an instructive
example of the research-driven evolution of a psychological con-
struct.

That the effects of a visual stimulus can persist beyond the
duration of the physical stimulus is easily demonstrated with the
phenomena of afterimages. The initial theoretical construct of iconic
memory bore a strong resemblance to a visual afterimage. Afterim-
ages are images that occur in response to a visual stimulus. They
commence after the offset of the visual stimulus, often last for several
seconds, and, given high-energy stimulation, can continue for sev-
eral minutes.

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