On the relations between crowding and visual masking.

To study the question of which processes contribute to crowding and whether these are comparable to those of visual temporal masking, we varied the stimulus onset asynchrony (SOA) between target and flankers in a crowding setting. Monotonically increasing Type A masking functions observedfor small spacings and large eccentricities indicate that the integration of information from target and flankers underlies crowding. Decreasing masking functions obtained for large spacings and small eccentricities relate processes of crowding to those contributing to Type B masking. In addition, Type B masking was more frequent with letter-like nonletter flankers than with letter flankers, suggesting that Type B masking, just like crowding over large areas, is due to higher level interactions. The rapid decrease of the effects of interletter spacing and eccentricity with increasing SOA indicates that positional information is transient.