The Chromatic and Achromatic Contrast Sensitivity Function in the Far Periphery

The contrast sensitivity function (CSF) defines one of the most fundamental aspects of vision: the boundary between the visible and the invisible. The CSF has been studied extensively since the 1950s, however most studies to date focused on the central region of vision and few have measured the CSF in the periphery. Furthermore, less investigation has been done examining the CSF with chromatic, as opposed to luminance, stimuli. The current study aims to fill this gap by examining the CSF across the entire horizontal visual field with achromatic and chromatic stimuli. Three curved wide-field displays were arranged in a semi-circle around the subjects. These monitors have a 1m circular curvature, so each point of the screen is equidistant from the subject, and combining all three allows for an effective screen size of 205°. A left/right 2AFC detection task was used to measure the CSF in 3 different experiments (Achromatic, Red-Green, and Yellow-Violet) via QUEST. Participants binocularly viewed the stimuli, which were 10deg Gabor patches of varying spatial frequency (0.1, 0.3, 0.5, 1, 3, 5, and 10 cpd). The stimuli were presented at 6 different locations along the horizontal visual field (5°, 15°, 45°, 60°, 75°, and 90° eccentricity). The measured CSFs in the more central regions of the visual field agreed with measurements from previous literature. However, achromatic sensitivities in the far periphery (>45°) were higher than models that account for peripheral contrast sensitivity would suggest. CSF models to date do not typically account for chromaticity and eccentricity together, making these data a valuable contribution to extend these models. These data will fill in an important gap in our understanding of human visual sensitivity that is vital for applications in full-field visual displays such as VR and AR, as well as cutting-edge technologies such as foveated rendering.