• University of Huddersfield Queensgate Huddersfield HD1 3DH

    United Kingdom

Accepting PhD Students

  • 47 Citations
  • 4 h-Index
20142020

Research output per year

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Personal profile

Google Scholar h-Index

16 Last checked 14 July 2020

Biography

A particular focus of my research is to investigate and understand the problem of visual crowding, where the recognition of letter targets (as indeed other objects in visual space) is disrupted by the presence of nearby contours. Our work has attracted international interest. We have demonstrated that in central vision (i.e. foveal) for near threshold stimuli, crowding operates over a fixed spatial distance irrespective of target size, which contradicts a popular explanation of crowding (Siderov J., Waugh S.J. & Bedell H.E. Foveal contour interaction for low contrast acuity targets. Vision Research, 2013; 77: 10-13 and Siderov J., Waugh S.J. & Bedell H.E. Foveal contour interaction on the edge: Response to Drs Coates and Levi. Vision Research 2014; 96:145-148). We were the first to show that the intensity of foveal crowding reduces under low levels of luminance (mesopic) (Bedell H.E., Siderov J., Waugh S.J., Zemanova R., Pluhacek F., & Musilova L. Contour interaction for foveal acuity targets at different luminance. Vision Research, 2013; 89:90-95) but not under total darkness (scotopic luminance) (Musilova L., Pluhacek F., Marten-Ellis S.M., Bedell H.E., & Siderov J. Contour interaction under photopic and scotopic conditions. Journal of Vision, 2018; 18(5): 1-11). This finding has implications when assessing vision clinically under low luminances (Pluhacek F. & Siderov J. Mesopic visual acuity is less crowded. Graefe’s Archive for Clinical and Experimental Ophthalmology, 2018. /doi.org/10.1007/s00417-018-4017-6).

We have confirmed experimentally early suggestions that letter recognition in children and in patients with amblyopia is crowded through a combination of low level spatial interactions (contour interaction) in addition to higher level influences through putative attentive mechanisms or possibly factors relating to eye movements (Bedell H.E., Siderov J., Formankiewicz, M.A., Waugh S.J., & Aydin S. Evidence for an eye- movement contribution to normal foveal crowding. Optometry and Vision Science 2015; 92: 237-245). An additional finding suggests a different time course for the development of visual acuity in children based on how crowding develops, which has not previously been reported (Norgett Y. & Siderov J. Effect of test chart configuration on crowding in strabismic amblyopia. Journal of Vision. 2017; 17: 1-14; Norgett Y. & Siderov J. Foveal crowding differs in children and adults. Journal of Vision, 2014; 14: 1-10 and Norgett Y. & Siderov J. Crowding in children’s visual acuity tests – effect of test design and age. Optometry and Vision Science, 2011; 88(8): 920-927).

Research Expertise and Interests

My research interests have centred on clinical and non-clinical problems in paediatric and binocular vision, particularly visual acuity (crowding), stereopsis and amblyopia, and research into the effectiveness of optometric procedures. I am available to supervise in these areas. 

Research Expertise and Interests

  • vision, crowding, stereopsis, amblyopia

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Research Output

  • 47 Citations
  • 4 h-Index
  • 11 Article
  • 1 Letter

Upturn of the contour-interaction function at small flanking bar-to-target separations

Siderov, J., Pluháček, F. & Bedell, H. E., 1 Feb 2020, In : Vision Research. 167, p. 1-7 7 p.

Research output: Contribution to journalArticle

Contrast Energy and Contour Interaction

Bedell, H., Siderov, J. & Pluháček, F., 1 Dec 2019, In : Optometry and Vision Science. 96, 12, p. 940-947 8 p.

Research output: Contribution to journalArticle

  • Lateral interference, effects of flankers and reference bar configuration on foveal depth discrimination thresholds

    Ocansey, S., Osuobeni, E. & Siderov, J., 1 Mar 2019, In : Vision Research. 156, p. 96-104 9 p.

    Research output: Contribution to journalArticle

    Assessment of Visual Acuity in Children Using Crowded Lea Symbol Charts

    Sailoganathan, A., Rou, L. X., Buja, K. A. & Siderov, J., 1 Aug 2018, In : Optometry and Vision Science. 95, 8, p. 643-647 5 p.

    Research output: Contribution to journalArticle

  • 2 Citations (Scopus)

    A standardized logarithm of the minimum angle of resolution visual acuity chart in Hindi

    Sailoganathan, A., Osuobeni, E. P. & Siderov, J., 1 May 2018, In : Indian Journal of Ophthalmology. 66, 5, p. 634-640 7 p.

    Research output: Contribution to journalArticle

    Open Access
  • 1 Citation (Scopus)

    Activities

    • 2 Membership of a Society or Institute
    • 1 Membership of committee

    Education Evaluation Commission – Higher Education Sector (External organisation)

    John Siderov (Chair)

    2017

    Activity: Membership typesMembership of a Society or Institute

    General Optical Council (External organisation)

    John Siderov (Member)

    2017 → …

    Activity: Membership typesMembership of a Society or Institute

    Quality Assurance Agency (External organisation)

    John Siderov (Chair)

    20132017

    Activity: Membership typesMembership of committee