Editing Iconic memory (section)

=== Temporal variations ===
Varying the time between the offset of the display and the auditory cue allowed Sperling to estimate the time course of sensory memory. Sperling deviated from the original procedure by varying tone presentation from immediately after stimulus offset, to 150, 500, or 1000 ms. Using this technique, the initial memory for a stimulus display was found to decay rapidly after display offset. At approximately 1000 ms after stimulus offset, there was no difference in recall between the partial-report and whole report conditions. Overall, experiments using partial report provided evidence for a rapidly decaying sensory trace lasting approximately 1000 ms after the offset of a display<ref name="Sperling" /><ref name="Averbach">{{cite book | last1 = Averbach | first1 = E | last2 = Sperling | first2 = G | author-link2 = George Sperling | title = Information Theory | chapter = Short-term storage of information in vision |editor1= C. Cherry | publisher = Butterworth | year = 1961 | location = London | pages = 196–211 }}</ref><ref>{{cite journal|last=Sperling|first=George|year=1967|title=Successive approximations to a model for short-term memory|journal=Acta Psychologica|volume=27|pages=285–292|doi=10.1016/0001-6918(67)90070-4|pmid=6062221}}<!--| access-date = 2011-03-11 --></ref>

==== Circle cue and masking ====
The effects of masking were identified by the use of a circle presented around a letter as the cue for recall.<ref>{{cite journal|last=Averbach|first=E|author2=A. Coriell|year=1961|title=Short-term memory in vision|journal=Bell System Technical Journal|volume=40|pages=309–328|doi=10.1002/j.1538-7305.1961.tb03987.x}}<!--| access-date = 2011-03-08 --></ref> When the circle was presented before the visual stimulus onset or simultaneously with stimulus offset, recall matched that found when using a bar or tone.  However, if a circle was used as a cue 100 ms ''after'' stimulus offset, there was decreased accuracy in recall.  As the delay of circle presentation increased, accuracy once again improved.  This phenomenon was an example of metacontrast masking.  Masking was also observed when images such as random lines were presented immediately after stimulus offset.<ref>{{cite journal|last=Sperling|first=George|year=1963|title=A model for visual memory tasks|journal=Human Factors|volume=5|pages=19–31|doi=10.1177/001872086300500103|pmid=13990068|s2cid=5347138 }}<!--| access-date = 2011-03-08 --></ref>