(Un)crowding is pre-attentive

In crowding, perception of a target deteriorates in the presence of nearby flankers. Crowding can be undone when additional flankers are presented, an effect known as uncrowding, which occurs when the flankers group with each other and ungroup from the target. A major question is whether this grouping process occurs automatically or requires attention. We investigated this question using a dual-task paradigm. Participants simultaneously performed a foveal discrimination task and a peripheral Vernier offset discrimination task. The foveal task was either feature-relevant with the crowding task (orientation or shape discrimination) or feature-irrelevant (color discrimination). In the peripheral task, participants reported the Vernier offset direction with the Vernier presented in isolation (baseline), surrounded by one square (crowding), or by seven squares (uncrowding). We found a main effect but no interaction, i.e., performance deteriorated in all three conditions (Vernier alone, crowding, uncrowding) because of the attentional load of the foveal task. However, the deterioration was roughly the same for the three conditions. We suggest that (un)crowding occurs with low attentional resources.