Rejection mechanisms for color singleton distractors operating on different time scales

Color singleton distractors interference is modulated by rejection mechanisms that take into account the distractors rate of occurrence at different locations. Here, to further address color-singleton distractor rejection, we used a modified version of the additional-singleton paradigm, where each trial consisted of four consecutive displays presented in rapid succession. In Experiment 1 the irrelevant singleton was either presented in the last display (single condition, 40% rate) or repeated in all four displays (repeated condition, 10% rate), with the two conditions appearing at separate locations. Contrary to common observations, we found that capture was much more attenuated at the repeated location, despite the lower distractor rate. Furthermore, we found no signs of target processing impairment at the location where capture was basically eliminated, whereas it was present where capture was robust. In Experiment 2, where both locations had repeated distractors, we found target processing impairment only at the location with the highest rate (40%); Experiment 3, indicated that suppression, regardless of any within trial distractor repetitions, becomes evident when the distractor rate is high enough (35%). Experiment 4 replicated these separate previous findings in a single experiment, within the same group of participants. The results suggest the possible existence of rejection mechanisms working on distinct time scales, based on within trial and across trials distractor repetitions. While the across trials mechanism seems to rely on a durable form of suppression to control capture, the within trial one might rely on short-term distractor expectation, or involve a volatile form of suppression.