Experiment 2 Manipulating Uncertainty About The Time Of Break Occurrence With A Forewarning

In experiment 2, uncertainty concerning the time of break presentation was manipulated. Two main conditions were compared: a cued condition, in which a cue presented 500 msec before the break onset informed participants that the break was imminent, and a no-cue condition, in which this information was not provided. In research on visual attention, cues for visual targets orient attention by reducing uncertainty about its spatial location (e.g., Posner, 1980). We applied the same reasoning to the temporal domain here by presenting a forewarning cue at a fixed time, 500 msec, before the break signal. By reducing uncertainty about temporal location of the break, the cue should have a significant impact on orienting attention toward the break occurrence. On the other hand, because the cue is perfectly valid and is presented on every trial in the cued group, another possible result is that, knowing they will be forewarned of the break occurrence, participants will stop shifting their attention. This implies, however, that attentional time-sharing in these conditions is under voluntary control and may be prevented.

The task was basically the same as that in experiment 1 in the continuous break-signal condition, with all trials including a break.

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