August 2023
Volume 23, Issue 9
Open Access
Vision Sciences Society Annual Meeting Abstract  |   August 2023
Crowding does not follow Gestalt principles in foveal and amblyopic vision
Author Affiliations & Notes
  • John A. Greenwood
    University College London, London, UK
  • Alexandra Zmuda
    University College London, London, UK
  • Annegret H. Dahlmann-Noor
    Moorfields Eye Hospital, London, UK
    NIHR Biomedical Research Centre, London, UK
  • Alexandra V. Kalpadakis-Smith
    University College London, London, UK
  • Footnotes
    Acknowledgements  Funded by the UK Medical Research Council & Moorfields Eye Charity
Journal of Vision August 2023, Vol.23, 4805. doi:
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      John A. Greenwood, Alexandra Zmuda, Annegret H. Dahlmann-Noor, Alexandra V. Kalpadakis-Smith; Crowding does not follow Gestalt principles in foveal and amblyopic vision. Journal of Vision 2023;23(9):4805.

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      © ARVO (1962-2015); The Authors (2016-present)

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Crowding is the disruption to object recognition that occurs in clutter, a process that strongly limits peripheral vision and becomes elevated in foveal/central vision with amblyopia (‘lazy eye’). Bottom-up ‘pooling’ models depict crowding as an unwanted integration of target and flanker elements, with the amount of disruption driven by the similarity between elements. In contrast, top-down ‘grouping’ approaches argue that crowding follows Gestalt principles of organisation. We reasoned that if crowding is driven by grouping, then wherever crowding occurs, grouping effects should follow. To test this, we compared crowding in peripheral vision with the typical and amblyopic fovea. Observers judged the orientation of a black Landolt-C target, with size-acuity thresholds measured via QUEST procedure. Stimuli were shown in typical peripheral vision (15deg.), the typical fovea, or amblyopic fovea (n=10 in each). In all groups, thresholds were low with an isolated target, and elevated when two black Landolt-C flankers (left/right of the target with matched sizes) or a surrounding box were added. This crowding effect was reduced with white flankers (due to decreased target-flanker similarity) for all groups. In peripheral vision, we replicate several grouping effects with the target amidst a row of six flankers: alternating black-and-white flankers gave strong elevations (‘target-flanker grouping’), while thresholds were reduced by all-white flankers (‘flanker-flanker grouping’) and a row of boxes (‘uncrowding’). Performance differed in both the typical and amblyopic fovea: although the alternating black-and-white flankers elevated thresholds, the all-white flankers and the row of ‘uncrowding’ boxes did not give performance improvements. We also replicate these patterns with narrower Vernier stimuli. Our results suggest that grouping effects derive from diverse processes, some of which are absent from foveal and amblyopic vision. The presence of crowding, and its modulation by target-flanker similarity, was nonetheless clear. We conclude that crowding and grouping are distinct processes.


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