On the extent and spatial profile of visual crowding

Skoczek, Kristian Paul 2023. On the extent and spatial profile of visual crowding. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Visual crowding is the deleterious effect of clutter causing interference in the perception of neighbouring targets. Crowding effects are particularly prominent in peripheral vision and are regarded as the main limiting factor in the perception of peripheral details. Crowding occurs when distractor elements are present within a particular spacing around a target of interest known as a crowding zone. Targets may take on aspects of the appearance of flankers or appear as an indistinct mixture of target and flanker features. These effects are strongest when flankers are immediately neighbouring the target and weaken as separation increases. Disruptions in target perception are also particularly strong when flankers are similar in appearance to the target. It is currently unclear how the influences of target-flanker similarity and target-flanker spacing lead to a combined influence on the perception of detailed targets. This thesis presents four studies investigating the effects of target-flanker similarity on the spatial dependencies of visual crowding in orientation. Manipulating the relative orientation of targets and flankers modulates the span over which systematic shifts in target appearance occurred as flankers encroached on the target. However, this transitionary span is consistently centred at a fixed distance from the target, which increases with eccentricity. This work presents a novel model of these changes at the limits of crowding zones – ‘the spatial profile of crowding’. This model reveals that common methods of estimating crowding zone extent (the target for a wide variety of crowding research) may overlook informative changes in how detailed perception of a target shifts in the presence of flankers, conflating aspects that are dependent and independent of flanker appearance. The spatial profile of crowding provides new insight into potential confounds in prior research and may aid the design of future work by strengthening associations between structural and psychophysical measures.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Optometry and Vision Sciences
Subjects:	R Medicine > RE Ophthalmology
Uncontrolled Keywords:	Visual Crowding, Psychophysics, Perception
Date of First Compliant Deposit:	1 June 2023
Last Modified:	01 Jun 2024 01:30
URI:	https://orca.cardiff.ac.uk/id/eprint/160086

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