Figure 1

Task conditions of the Sternberg paradigm. The four task conditions determined by the nature of the probe items. (1) Recent negative condition: The probe did not match any items of the current target set but had occurred in both previous trials; (2) Non-recent negative condition: The probe did not match any items of the current target set or of the two previous trials; (3) Recent positive condition: The probe matched an item of the current target set and had occurred in both previous trials; (4) Non-recent positive condition: The probe matched an item of the current target set but had not occurred in the two previous trials.