BORIS Theses

BORIS Theses
Bern Open Repository and Information System

Challenging the similarity rule of visual crowding: When detrimental clutter becomes beneficial uniformity

Rummens, Koen (2022). Challenging the similarity rule of visual crowding: When detrimental clutter becomes beneficial uniformity. (Thesis). Universität Bern, Bern

23rummens_k.pdf - Thesis
Available under License Creative Commons: Attribution-Noncommercial-No Derivative Works (CC-BY-NC-ND 4.0).

Download (2MB) | Preview


In real life, objects are seldomly encountered in isolation but are more often than not surrounded by other items. Context has been shown to strongly modulate whether and how objects are perceived. In visual crowding, nearby items (‘flankers’) prevent the accurate perception of a target object. One of the central crowding rules concerns its dependence on target-flanker similarity, with usually weak crowding when target and flankers differ on a given feature. For instance, the similarity rule predicts the ‘polarity advantage’: the superior identification of a crowded target when flanked by opposite rather than same contrast polarity items. The usual benefit of low target-flanker similarity is well explained by grouping: when the target is easily segmented from its flankers, such weak target-flanker grouping typically yields mild crowding. Here, in three studies, I demonstrate strong limitations to the generality of the similarity rule. In the first study, it was revealed that the usual benefit of low target-flanker similarity did not transfer to peripheral word recognition. In particular, word recognition deteriorated when word parts – either syllables or non-syllables - alternated in contrast polarity compared to words consisting of all same contrast polarity parts. In the second study, the similarity rule –typically shown with regard to a single crowded target – was reversed when multiple crowded targets were task-relevant. When neighboring trigram letters had the same versus opposite contrast polarity, performance was worse when reporting the central letter only but surprisingly superior when reporting all letters. In the third study, I show that interactions between two features - contrast polarity and orientation – can break the similarity rule of crowding. When discriminating the central line tilt within a line triplet, the usual advantage of opposite compared to same contrast polarity flankers (relative to the target) depended on flanker orientations. The polarity advantage was found with upright (||) and bidirectional (\/ or /\) flankers, but was absent with unidirectional flankers (\\ or //). Taken together, the current findings strongly challenge the generality of the similarity rule. I propose that attentional and configural factors can overcome the usual cost of strong grouping of target and flankers, revealing benefits of stimulus uniformity instead.

Item Type: Thesis
Dissertation Type: Cumulative
Date of Defense: 21 October 2022
Subjects: 100 Philosophy > 150 Psychology
Institute / Center: 07 Faculty of Human Sciences > Institute of Psychology > Cognitive Psychology, Perception and Methodology
Depositing User: Sarah Stalder
Date Deposited: 21 Nov 2023 15:33
Last Modified: 21 Nov 2023 23:25

Actions (login required)

View Item View Item