Figure 1.

A variation of the Sternberg working memory task was given under two conditions. a) In the storage condition, subjects encoded 1 or 2 targets (encoding phase). Note that in the example, 2 targets are shown, but on half the trials, only 1 target was shown. Then, subjects silently rehearsed these targets across a delay (traditionally called the maintenance phase, but here we use the term “delay” phase). Finally, at the presentation of a letter probe, subjects indicated whether the probe matched either of the targets (retrieval phase). b) In the manipulation condition, the encoding phase was identical to that in the storage condition. However, in the delay phase, instead of simply rehearsing the targets, subjects counted two alphabetical letters forward of each. Then they rehearsed these newly identified targets. In the retrieval phase, subjects indicated whether the probe matched either of the newly identified targets (rather than the original targets). In both figures, the box wave indicates when stimuli were visible on the screen.