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Contrast constancy is the perceptual ability to perceive the contrast of targets in the environment as constant, even as sensory constraints reduce the contrast of the image transmitted up the optic nerve to the brain. Here, we demonstrate a new form of contrast constancy where humans correct for the contrast lost via defocus blur. We constructed a custom psychophysical rig capable of presenting light from three different distances simultaneously along the same line of sight. Subjects viewed stimuli monocularly through a 4mm artificial pupil using a bite bar. Each trial began with a focus target presented at 80cm. After the subject focused the target, standard and comparison targets—narrow bandwidth Gabors embedded in a hard-edged disks—were presented simultaneously for 200ms. A narrow band Gabor was used because defocus alters its contrast without altering its spatial wave form. The hard-edged disk …