Figure 1.

Schematic illustration of cue and stimulus trials for the motion and color conditions. (A) Stimulus sequence for the motion attention condition showing an informative specific feature cue trial (left in part A), where the cue (auditory word “right”) informed the subject of the motion of the upcoming target (if the trial contained any motion – see text). At right in part A, a non-informative general dimension cue trial is illustrated; here the subjects are presented only with the word “motion”, indicating that on that trial, if there is motion, it is equally likely to be left, right, up or down in direction. The cue, presented auditorily in a male voice, was followed by an interval of 2500 ms (cue-to-stimulus display interval, onset to onset) and then a display of randomly moving dots appeared for 1000 ms. In the midst of this presentation, there could be a motion target, where the dots briefly move in a coherent direction – the same direction as was cued if there is motion on that trial. During the motion condition, there were also task-irrelevant color targets that could briefly appear (see text for details). The plus (+) sign in the center of each panel is the fixation point where subjects were required to maintain their gaze throughout each trial. Each trial was followed by an intertrial interval of 1000 ms. (B) Stimulus sequences for the color attention condition. Again the trial on the left of part B depicts an informative specific feature cue trial wherein subjects are cued to a specific color (e.g., blue). The right side of part B shows a non-informative general dimension trial. As in the motion attention condition, task-irrelevant coherent motion of the dots could also take place. Each trial lasted 4.5 seconds.