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Derek H Arnold, Eleanor Moses, Melvyn A Goodale; Sharpening Vision by Adapting to flicker. Journal of Vision 2019;19(10):45. doi: https://doi.org/10.1167/19.10.45.
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© ARVO (1962-2015); The Authors (2016-present)
Spatial form and stimulus dynamics were once thought to be encoded by independent visual processes. However, a wealth of physiological (see Lennie, 1998, Perception) and psychophysical (e.g. Nishida, 2004, Current Biology) evidence has now established co-joint encoding of form and motion. Notably, visual mechanisms responsive to dynamic inputs tend to encode spatial form at a low spatial resolution. Recently, we showed this coupling can be leveraged to transiently sharpen spatial vision (Anold et al., 2016, PNAS). Here we replicate a core finding of that investigation, and explore its neurophysiological underpinnings via EEG. Again, we find that people are able to read finer text after adapting to dynamic visual white noise. In this study, people adapted and read text in positions centred above or below fixation. Behaviourally, adaptation was advantageous only for fine text presented below fixation, and this was associated with reduced responses recorded via occipital sensors from ~140 to 210ms post word presentations. Our data are consistent with flicker adaptation transiently reducing the magnitude of a low-spatial-resolution form signal in occipital cortex that would normally sum with higher-spatial resolution signals. This and similar observations suggest a need for more nuanced accounts of the functional architecture of human vision – which encompass both co-joint encodings of visual attributes, and allow for the wealth of evidence substantiating functional specialisation.
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