Evidence for Categorical Crowding

An object easily recognised in isolation is hampered when other objects are situated close to it. This phenomenon is called crowding. It is generally thought that crowding affects object recognition only at the level of feature combination. However, recent studies have shown that if flankers and targets belong to different categories crowding is weaker, calling into question the above assertion. Nevertheless, these results can be explained in terms of featural-differences between categories. The current study tests if category-level (i.e., high-level) interference in crowding occurs when featural-differences are controlled for. The first experiment used letters and numbers as targets and flankers in a two-by-two study design. We found lower critical spacing when targets and flankers belonged to different categories, replicating previous results. In a second experiment, using a font that ensured that both categories had the same feature-set, we observed the same, albeit weaker, category-dependent effect. This suggests that although featural differences can account partly for the reduction, category-level effects persist even when featural differences are fully controlled for. We conclude that crowding results from not only the well-documented feature-level interactions but also additional interactions at a level where objects are grouped by meaning