The Discovery of the Venetian Blind Effect: A Translation of Münster (1941)

Münster, the first to discover the effects of a luminance disparity on perceived depth, described two: (1) The apparent displacement in depth of one of a pair of objects relative to the other when viewed with a luminance disparity, and (2) The apparent overall displacement of objects viewed with a luminance disparity away from the observer. The first, which is the Venetian blind effect, was ascribed to irradiation. Current evidence suggests that irradiation fails to account for the effect, implying that neural mechanisms are involved. The second was thought to be related to the perceived distance of a monocularly viewed stimulus embedded in a dichoptically viewed stimulus. However, the measured effect was probably due to aniseikonia. Münster offered a compelling and seemingly complete account of the Venetian blind effect using irradiation theory. Münster’s irradiation theory effectively inhibited further research by relegating the perceived depth displacement to largely non-neural mechanisms. It is now becoming clear that Münster’s measurement of the Venetian blind effect represents the discovery of one of several mechanisms supporting stereopsis, though he and many others failed to recognize that discovery at the time.