Abstract
The involvement of disparity detectors in the perception of spatial-frequency doubling in a flickering grating was tested by viewing the grating horizontally. Frequency doubling was unimpaired, and must therefore occur independently of disparity detection. A distortion model of frequency doubling was compared with a flicker-detection model, in predicting the appearance of nonsinusoidal gratings. The results support the flicker-detection model but not the distortion model. Physiological considerations suggest that spatial-frequency doubling may be mediated by the transient response of the amacrine cells in the retina.