Early and late selection in partial report: evidence from degraded displays

In studies of iconic memory using the bar-probe task, subjects see a brief display of target letters and are probed by an arrow to report one of them. According to the classic early-selection account, subjects use the probe to select material for perceptual analysis from a precategorical (iconic) memory, but according to late-selection theories, subjects first identify the letters and then use the probe to select one letter for report from the set of categorized items. Pashler (1984) based his test for the locus of selection on a manipulation of display quality in previewed displays. He presented a target for 200 msec and then added a probe, together with the target, for an additional 150 msec. Reducing the target's stimulus quality increased response latency. If the subjects identified the characters before the probe appeared and then selected an item for report, the clarity of the original array should not have affected response latency. Hence, Pashler concluded that his subjects used the probe to select from a precategorical store (early selection). Pashler's experiment did not force subjects to rely on memory of the target; hence, although his experiment documented a situation in which subjects used early selection, it did not rule out late selection in studies of information persistence. We replicated Pashler's findings and, using his logic, showed that when subjects are forced to rely on memory of the target, they select from a categorized store.