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Eliza Burton, John Wattam-Bell, Marko Nardini; The impact of optical blur on cortical responses to global form and motion. Journal of Vision 2012;12(9):754. doi: https://doi.org/10.1167/12.9.754.
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Visual event-related potentials (VERPs) have previously been used to study the development of form and motion processing in infancy. However, the extent to which infants’ limited visual acuity might impact on their global form and motion processing is not fully understood. Previously, psychophysical coherence thresholds for both global form and motion sensitivity in adults were similarly resistant to blur with lenses of up to +12 dioptres (Braddick et al, Perception 36, ECVP Abstract Supplement, 2007). Our study assessed the effects of optical blur on steady state VERPs for coherent form and motion. Adult participants viewed concentric patterns of short arcs (form stimulus) or short motion trajectories (motion stimulus), each of which alternated at 2 Hz between 100% coherent and incoherent global organisation. VERPs were recorded for four levels of blur achieved using lenses of −0.12, +2.5, +5.5 and +10 dioptres. Increasing blur was associated with a progressive decrease in signal amplitude at the fundamental frequency (F1) for both form and motion stimuli, implying reduced responses to global coherence. This suggests that form and motion responses in populations with low acuity could be limited by this factor. The study highlights the need to take acuity into account when investigating form and motion responses in low acuity populations including infants and clinical groups. Future studies will aim to investigate impacts of blur on form and motion stimuli varying in spatial and temporal frequency, i.e. segment size and length (form), and dot size and speed (motion). This will help to determine the optimal stimuli to use for studying form and motion processing in low acuity populations.
Meeting abstract presented at VSS 2012
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