Monocular blur impairs heading judgements from optic flow

Monocular blur sometimes impairs locomotion; however, it is not always clear when this will happen. Optic flow (the apparent motion of scene texture elements that occurs during self-motion) provides powerful signals about the direction of travel. Here, we test whether monocular blur impairs heading...

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Main Authors: William E. A. Sheppard, Rachel O. Coats, Richard M. Wilkie, Rigmor C. Baraas
Format: Article
Language:English
Published: SAGE Publishing 2025-01-01
Series:i-Perception
Online Access:https://doi.org/10.1177/20416695251317148
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author William E. A. Sheppard
Rachel O. Coats
Richard M. Wilkie
Rigmor C. Baraas
author_facet William E. A. Sheppard
Rachel O. Coats
Richard M. Wilkie
Rigmor C. Baraas
author_sort William E. A. Sheppard
collection DOAJ
description Monocular blur sometimes impairs locomotion; however, it is not always clear when this will happen. Optic flow (the apparent motion of scene texture elements that occurs during self-motion) provides powerful signals about the direction of travel. Here, we test whether monocular blur impairs heading perception from optic flow compared to full vision under various levels of optic flow degradation. Participants ( N  = 52, mean age = 30 years) completed contrast sensitivity, visual acuity, and heading perception tasks with rich or degraded optic flow, with or without monocular blur (0.4 logMAR Bangerter filter over the non-dominant eye, full vision in the dominant eye). Heading perception was assessed using a browser-based task where the participants viewed a 3-second video consistent with self-motion over a textured ground plane (moving towards the horizon at an offset heading ranging from −20 to +20°) and identified the point on the horizon towards which they were travelling. The measures of each participant's performance were the absolute and directional angular error between the heading offset and their response. Monocular blur and degraded flow were associated with an increase in absolute heading error and a larger underestimation of heading angle, with the worst performance observed when monocular blur and degraded flow were combined. These results suggest that the impact of monocular blur on heading perception becomes apparent only when optic flow signals are weak (e.g., night-time driving). These findings support the theory that monocular blur and the richness of visual information interact to produce deficits in heading perception.
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institution Kabale University
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series i-Perception
spelling doaj-art-88cf88c00efb4052b8af8a050f3c3bb42025-08-20T03:28:47ZengSAGE Publishingi-Perception2041-66952025-01-011610.1177/20416695251317148Monocular blur impairs heading judgements from optic flowWilliam E. A. SheppardRachel O. CoatsRichard M. WilkieRigmor C. BaraasMonocular blur sometimes impairs locomotion; however, it is not always clear when this will happen. Optic flow (the apparent motion of scene texture elements that occurs during self-motion) provides powerful signals about the direction of travel. Here, we test whether monocular blur impairs heading perception from optic flow compared to full vision under various levels of optic flow degradation. Participants ( N  = 52, mean age = 30 years) completed contrast sensitivity, visual acuity, and heading perception tasks with rich or degraded optic flow, with or without monocular blur (0.4 logMAR Bangerter filter over the non-dominant eye, full vision in the dominant eye). Heading perception was assessed using a browser-based task where the participants viewed a 3-second video consistent with self-motion over a textured ground plane (moving towards the horizon at an offset heading ranging from −20 to +20°) and identified the point on the horizon towards which they were travelling. The measures of each participant's performance were the absolute and directional angular error between the heading offset and their response. Monocular blur and degraded flow were associated with an increase in absolute heading error and a larger underestimation of heading angle, with the worst performance observed when monocular blur and degraded flow were combined. These results suggest that the impact of monocular blur on heading perception becomes apparent only when optic flow signals are weak (e.g., night-time driving). These findings support the theory that monocular blur and the richness of visual information interact to produce deficits in heading perception.https://doi.org/10.1177/20416695251317148
spellingShingle William E. A. Sheppard
Rachel O. Coats
Richard M. Wilkie
Rigmor C. Baraas
Monocular blur impairs heading judgements from optic flow
i-Perception
title Monocular blur impairs heading judgements from optic flow
title_full Monocular blur impairs heading judgements from optic flow
title_fullStr Monocular blur impairs heading judgements from optic flow
title_full_unstemmed Monocular blur impairs heading judgements from optic flow
title_short Monocular blur impairs heading judgements from optic flow
title_sort monocular blur impairs heading judgements from optic flow
url https://doi.org/10.1177/20416695251317148
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AT rachelocoats monocularblurimpairsheadingjudgementsfromopticflow
AT richardmwilkie monocularblurimpairsheadingjudgementsfromopticflow
AT rigmorcbaraas monocularblurimpairsheadingjudgementsfromopticflow