Abstract
Question: Pictorial objects, other than physical objects, exist only in the mind of the beholder. Pictorial space is relief space and therefore not Euclidean, e.g., pictorial objects have only frontal sides thus cannot turn about certain axes. Pictorial relief is due to the pictorial cues. For isoluminant renderings all cues related to luminance contrast are missing. It has been suggested that as a result 3D pictorial space almost vanishes under isoluminant conditions. To what extent does pictorial space deteriorate under isoluminant conditions?
Methods: Stimuli were monochrome halftone photographs, either used as such or transposed to Red/Green or Green/Red hue modulations. In a previous experiment we probed pictorial pose. In he present experiment we used a method of probing pictorial depth via attitude settings of a gauge figure.
Results: The results of this experiment confirm the findings of the earlier study. In both experiments the depth reconstructions for Red/Green, Green/Red and monochrome conditions are very similar and observers perform equally well in Red/Green, Green/Red and monochrome conditions. The general conclusion is that observers do not do worse with the isoluminant Red/Green and Green/Red transposed images. Much of the depth structure of pictorial space is apparently preserved. The notion that spatial representations are not sustained under isoluminant conditions should be applied with caution.