Iconic memory: fallacies persist (?)

Two recent papers (Coltheart, 1980; Long, 1980) have evaluated literature on the relationship between "iconic memory" and "visible persistence." In doing this, both writers focused on methods of measurement of these phenomena and the influence on them of luminance and duration. On the basis of his literature review, Coltheart (p. 210) concluded "the distinction between iconic memory and visible persistence is not merely terminological: they are actually different psychological processes." In comparison, Long concluded (p.814) that "the appealing parsimony of equating visible persistence and iconic memor)’, which has been the traditional view (e.g., Neisser, 1967), need not be abandoned." The present paper evaluates the strength of Long’s arguments, and concludes that: (1) conflict arises over problems of definition; (2) the data from experiments using methods considered inappropriate by Long are very consistent and yield useful information about visible persistence; (3) it consequently cannot be claimed that the bulk of the evidence supports a positive relationship between stimulus intensity (or duration) and persistence duration; (4)it is misleading to claim that Long’s data, usually collected under a specific combination of somewhat extreme experimental conditions, is representative of data in the area; and (5)iconic memory and visible persistence cannot be readily equated.