Crowding and shape representations

In crowding, target perception deteriorates when flanking elements are added. Crowding is traditionally characterized by target-flanker interactions which are (1) deleterious, (2) spatially confined within Bouma’s window, and (3) feature specific. Here, we show that none of these assumptions universally hold true. We determined vernier offset discrimination thresholds at 9° of eccentricity. When the vernier was embedded in a square, thresholds increased compared to the unflanked threshold. Surprisingly, when the vernier was flanked by three additional squares on either side, crowding strongly decreased. Similar results hold true for other shapes, including unfamiliar, irregular shapes. In addition, changing the flanking shapes’ orientations led to increases in crowding. These results show that (1) more flankers can decrease crowding, (2) crowding strength can be determined by elements outside Bouma’s window and (3) shape processing can determine vernier offset thresholds. We propose that visual acuity for each element in the visual scene depends on all elements in the entire visual field and, on top of that, on the overall spatial configuration. In addition, these results provoke the question of whether the human brain is, indeed, coding any type of shapes at all locations in the visual field.