Do masks terminate the icon?
Iconic memory is operationally defined by part-report experiments (Sperling, 1960). If a mask is presented after the target, the mask is thought to be superposed on the target in the iconic representation, or to displace it from the representation. But could a cue presented after a pattern mask still allow selection within the target array? A target array of letters was followed by a checkerboard mask. We compared two target-mask interstimulus intervals (ISIs; 0 and 100 ms), and six cue delays. At ISI = 0 ms, performance was at chance, for part report and whole report. At ISI = 100 ms, with the shortest cue delay, observers demonstrated a part-report advantage of 25-30%. As cue delay increased the part-report advantage decreased. These results are inconsistent with an iconic memory that is automatically displaced or overwritten by new information. We consider two alternatives: a second-stage store, which represents letters in terms of their high-level features and which the mask cannot penetrate, or a four-dimensional store that preserves separately the representations of the target and its aftercoming mask. We discuss the implications of our results for studies that use backward masking to "terminate the icon".
University of Cambridge, Cambridge, UK. hannah.smithson@durham.ac.uk
Hannah
H
Smithson
John
J
Mollon
D003463:Cues; D006801:Humans; D008568:Memory; D010470:Perceptual Masking