Evolution of a Theoretical Construct: Changes in the Construct of Iconic Memory over 30 Years of Research
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 construct.
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. Afterimages 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 several minutes.