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Donders Institute Geuzebroek, Albert van den Berg; Peripheral involvement of the extraction of the gist of the scene.. Journal of Vision 2017;17(10):563. doi: https://doi.org/10.1167/17.10.563.
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© ARVO (1962-2015); The Authors (2016-present)
Human observers are capable to rapidly extract spatial information to get a sense of their environment as well as its functional potential. This phenomenon is called the gist of the scene, and in this study, we aimed to create a task to explore it in patients with homonymous visual field defects. It is thought that the gist of the scene is derived from networks with larger-sized receptive fields. And indeed previous work showed that the peripheral visual field, which is tuned to the lower spatial frequencies, is most useful for the scene gist extraction. However, the images only extended to 20o and the content of the scene information was depending on foveal or peripheral presentation. In our study, 15 healthy participants were piloted on a two-alternative forced choice, discriminating scenes presented for 150 ms. They made this discrimination based on either basic-level features (ocean vs field) or global-level features (man-made vs natural and concealment). All images had identical mean contrast and luminance and the signal-to-noise ratio was systematically manipulated with pink noise. We assessed two conditions: foveal presentation where the scene was compressed in the central 12o and peripheral presentation where the scene was presented at 40o while occluding the central 12o. Proportion correct increased significantly more with signal-to-noise ratio when presented peripheral than foveal. This indicates that the periphery is more robust to noise than foveal vision. However, this effect was less pronounced for ocean vs field than both global-level discriminations and for concealment than for naturalness. This can be accounted for by general difficulty of the discrimination tasks. In conclusion, we validated an objective measurement of peripheral involvement in gist recognition. This task will give us the possibility to further explore the peripheral gist extraction in patients that suffer from visual field defects.
Meeting abstract presented at VSS 2017
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