The shielding function of task sets and its relaxation during task switching.

The goal of the presented experiments was to investigate the dynamic interplay of task shielding and its relaxation during task switching. Task shielding refers to the finding that single task sets in terms of 2-choice categorization rules help shielding against distraction from irrelevant stimulus attributes. During task switching, this shielding should temporarily be relaxed to prevent the perseveration of the previous task, on the downside making the system more vulnerable toward the intrusion of irrelevant information. Participants had to switch between a digit and a letter categorization task. An irrelevant stimulus feature (Experiment 1: color, Experiment 2: font) varied randomly, orthogonal to the task. The presence or absence of an interaction of the irrelevant feature (switch vs. repetition) and the response (switch vs. repetition) was taken as evidence for the absence or presence of task shielding, respectively. Replicating previous results, irrelevant feature and response did not interact on task repetitions, indicating successful shielding. On task switches, however, the irrelevant feature interacted with the response, supporting the assumption that task shielding is temporarily relaxed during task switching.