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Characterising the in-out asymmetry in visual crowding

Chakravarthi, Ramakrishna and Rubruck, Jirko and Kipling, Nikki and Clarke, Alasdair (2021) 'Characterising the in-out asymmetry in visual crowding.' Journal of Vision, 21 (11). pp. 1-14. ISSN 1534-7362

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An object’s processing is impaired by the presence of nearby clutter. Several distinct mechanisms, such as masking and visual crowding, are thought to contribute to such flanker induced interference. It is therefore important to determine which mechanism is operational in any given situation. Previous studies have proposed that the in-out asymmetry (IOA), where a peripheral flanker interferes with the target more than a foveal flanker, is diagnostic of crowding. However, several studies have documented inconsistencies in the occurrence of this asymmetry, particularly at locations beyond the horizontal meridian, casting doubt on its ability to delineate crowding. In this study, to determine if IOA is diagnostic of crowding, we extensively charted its properties. We asked a relatively large set of participants (n=38) to identify a briefly presented peripheral letter flanked by a single inward or outward letter at one of four locations. We also manipulated target location uncertainty and attentional allocation by blocking, randomising or precueing the target location. Using multi-level Bayesian regression analysis, we found robust IOA at all locations, although its strength was modulated by target location, location uncertainty and attentional allocation. Our findings suggest that IOA can be an excellent marker of crowding, to the extent that it is not observed in other flanker-interference mechanisms such as masking.

Item Type: Article
Uncontrolled Keywords: Crowding; masking; inner-outer asymmetry; attention; location uncertainty
Divisions: Faculty of Science and Health
Faculty of Science and Health > Psychology, Department of
SWORD Depositor: Elements
Depositing User: Elements
Date Deposited: 18 Jan 2022 16:23
Last Modified: 18 Aug 2022 10:43

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