Crowding of crowding leads to uncrowding

In crowding, target discrimination is impaired by flanking elements. What happens if a target is neighbored by flankers A and in addition by further flankers B? According to pooling models, crowding is the consequence of averaging features of target and flankers. Hence, pooling models predict strong crowding when the target is flanked by two flankers. We determined offset discrimination thresholds for verniers at 9° of eccentricity. When the vernier was embedded in a square, thresholds increased compared to the unflanked threshold - a classical crowding effect. Surprisingly, when adding more squares, thresholds did not increase, but crowding almost vanished. Hence, crowding of crowding leads to uncrowding. We propose that this un-crowding effect can be explained in terms of grouping. Grouping between the vernier and the central square leads to crowding by the Gestalt principle of common region. Grouping of the central and the neighboring squares by the Gestalt principle of similarity, leads to ungrouping of the vernier, and to un-crowding.