Fig. 1.

Example trial sequence for the four experiments. On each trial, participants were briefly shown a cue that was either nonpredictive or predictive of the likelihood of a task-switch or task-repeat trial, followed by a blank screen. In Experiments 1 and 2, the cue presentation was followed by a visual mask, whereas in Experiments 3 and 4, the cues were rendered supraliminal by removing the mask. After cue presentation, there was a jittered delay before participants were shown a letter stimulus surrounded by a colored rectangle, which cued the category-appropriate judgment (consonant/vowel vs. uppercase/lowercase) that participants performed. Note that in Experiments 2 and 4, participants were explicitly informed of the predictive or nonpredictive relationships that each cue had with task-switch or task-repeat trials.