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Anita J. Simmers, Peter J. Bex; Modelling The Perceptual Distortions in Amblyopia. Journal of Vision 2004;4(8):760. doi: 10.1167/4.8.760.
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© ARVO (1962-2015); The Authors (2016-present)
Many amblyopes report both spatial and temporal instability in their suprathreshold perceptions of sine-wave gratings, however the visual system typically processes images of far greater complexity. We consider the possibility that such perceptual distortions can be characterised as elevated uncertainty of the spatial phase of image components and test this hypothesis with supra-threshold natural images. In the first experiment natural images were modified by removing all components above a cut-off spatial frequency (blurring) or by randomising their phases. Amblyopic and normal vision observers discriminated such blur- and phase-distorted images from unaltered images at the same cut off point, indicating that high spatial frequency structure is not encoded by the amblyopic visual system rather than being encoded noisily. In the second experiment, noise was added to the phases of components within one-octave bands of natural images. Amblyopic observers were less sensitive than normal vision observers to image distortions introduced by these phase manipulations at all spatial frequencies tested. These results suggest that even when the amblyopic visual system can resolve image structure, the phase of visible components is represented with greater internal noise.
Medical Research Council (AJS) and Wellcome (PJB)
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