Photopic visual phantom illusion: its common and unique characteristics as a completion effect

An illusion similar to the stationary visual phantom illusion presented earlier by Gyoba (1983, Vision Research 23 205-211) is reported. This illusion is visible in photopic vision and we have tentatively named it the 'photopic phantom illusion'. A typical example of this illusion is a white and light-gray square-wave grating occluded by a black region. In this figure, a phantom grating running across the occluder with clear contours but less contrast, is seen. The critical spatial frequencies of photopic phantoms have been measured and compared with those of scotopic phantoms that have been reported previously, revealing a great resemblance between them. We discuss the characteristics of this illusion in terms of transparency, stereoscopic viewing, and perceptual completion.