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bioRxiv · 10.1101/2021.06.21.449339

Did you see it? A Python tool for psychophysical assessment of the human blind spot

Ling, X.·Silson, E. H.·McIntosh, R. D.
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Abstract

The blind spot is a region in the temporal monocular visual field in humans, which corresponds to a physiological scotoma within the nasal hemi-retina. This region has no photoreceptors, so is insensitive to visual stimulation. There is no corresponding perceptual scotoma because the visual stimulation is "filled-in" by the visual system. Investigations of visual perception in and around the blind spot allow us to investigate this filling-in process. However, because the location and size of the blind spot are individually variable, experimenters must first map the blind spot in every observer. We present an open-source tool, which runs in Psychopy software, to estimate the location and size of the blind spot psychophysically. The tool will ideally be used with an Eyelink eye-tracker (SR Research), but it can also run in standalone mode. Here, we explain the rationale for the tool and demonstrate its validity in normally-sighted observers. We develop a detailed map of the blind spot in one observer. Then, in a group of 12 observers, we propose a more efficient, pragmatic method to define a "safe zone" within the blind spot, for which the experimenter can be fully confident that visual stimuli will not be seen. Links are provided to this open-source tool and a manual.

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Ling, X., Silson, E. H., McIntosh, R. D.. 2021-06-22. Did you see it? A Python tool for psychophysical assessment of the human blind spot. https://doi.org/10.1101/2021.06.21.449339

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