Cite as:
Manassi M, Sayim B, Herzog M H, 2011, "Grouping trumps pooling and centroids in crowding" Perception 40 ECVP Abstract Supplement, page 182

Grouping trumps pooling and centroids in crowding

M Manassi, B Sayim, M H Herzog

In the periphery, discrimination of a target is usually impaired by flanking elements. This crowding effect is often explained in terms of pooling, ie target and flanker signals are averaged. The pooling hypothesis predicts stronger crowding when more flankers are presented. The centroid hypothesis, on the contrary, predicts that the more flankers are presented the weaker is the crowding. Here, we show that performance can both improve and deteriorate when more flankers are presented, depending on the layout of the flanker configuration. At 4° eccentricity, we determined offset discrimination thresholds for verniers embedded in regularly spaced arrays of flankers. The flankers were either shorter, of the same length, or longer than the vernier. We also presented the short flankers arranged in a spatially irregular fashion. Performance improved when increasing the number of shorter and longer regular flankers, and did not change for same-length, regular flankers. In contrast, performance deteriorated when increasing the number of irregular flankers. These results challenge both the pooling and centroid hypotheses. Instead, we propose that grouping determines crowding. Crowding is weak or absent when the vernier does not group with the flankers and strong when vernier and flankers group.

These web-based abstracts are provided for ease of seaching and access, but certain aspects (such as as mathematics) may not appear in their optimum form. For the final published version of this abstract, please see
ECVP 2011 Abstract Supplement (complete) size: 2206 Kb

[Publisher's note: The abstracts in this year's ECVP supplement have been published with virtually no copy editing by Pion, thus the standards of grammar and style may not match those of regular Perception articles.]