Compatible and incompatible representations in visual sensory storage.

Sensory storage shows a short-lived part-report advantage that survives an aftercoming visual noise pattern (Smithson & Mollon, 2006). We tested whether such an advantage survives different types of high-contrast mask. The target was a 3 × 4 array of digits. The mask could be (a) a noise pattern, (b) an array of eights, or (c) an array of random digits. In a preliminary experiment, target and mask were interleaved (at 140 Hz) and target contrast was varied to determine the level at which performance fell to chance. In the main experiment, target and mask were separated by an inter-stimulus-interval (ISI) of 100, 150, or 200 ms. An auditory part-report cue that was presented 240 ms after target offset supported a part-report advantage at all ISIs for noise masks, at ISIs greater than 100 ms for digit-8 masks, but not at any ISI for random-number masks. Increasing cue delay, in the range 240 to 730 ms, produced a decline in the advantages we measured. The differences in part-report superiority with different types of mask call for revision of the model of visual sensory storage as a single canvas on which successive items are superposed. When mask and target are sufficiently different, a representation of low-contrast target digits can be maintained independently of the representation of an aftercoming, high-contrast mask. However, when the same target is followed by a mask composed of high-contrast random digits, an independent representation of the target does not remain available for access.