Perceptual load is not always a crucial determinant of early versus late selection

The perceptual load hypothesis posits that early and late selection occurs under conditions of high and low perceptual load, respectively. Recent work, however, suggests that the absence of a congruency effect in high-load trials - the behavioral signature of early selection in studies of perceptual load - may not provide an exhaustive index of failing to identify task-irrelevant distractors. Prior research also suggests that the congruency sequence effect (CSE) - a modulation of the congruency effect after incongruent relative to congruent trials - provides complementary information about whether participants identify distractors. We therefore conducted a novel test of the perceptual load hypothesis that employed both the congruency effect and the CSE as measures of distractor identification. Experiment 1 revealed that distractors were identified not only in low-load trials but also in high-load trials wherein there was no overall congruency effect. Experiment 2 further revealed which task parameters allowed us to observe such "hidden" distractor identification. These findings suggest that perceptual load is not always a crucial determinant of early versus late selection.