TYPES OF SIZE DISPARITY AND THE PERCEPTION OF SURFACE SLANT

We examined (i) perceived slant of a textured surface about a vertical axis as a function of disparity magnitude for horizontal-size dispari ty, vertical-size disparity, and overall-size disparity; and (ii) inte ractions between patterns with various types and magnitudes of size di sparity and superimposed or adjacent zero-disparity stimuli. Horizonta l-size disparity produced slant which increased with increasing dispar ity, was enhanced by superimposed zero-disparity stimuli, and induced contrasting slant in superimposed or adjacent zero-disparity stimuli. Vertical-size disparity produced opposite slant (induced effect) which was reduced to near zero by a superimposed zero-disparity pattern and both patterns appeared as one surface. Adjacent vertical-size-dispari ty and zero-disparity patterns appeared as separate surfaces with a wi de curved boundary. Overall-size disparity produced slant which was en hanced by a superimposed zero-disparity pattern and less so by a zero- disparity line, and induced more slant in a zero-disparity line than i n a zero-disparity pattern. The results are discussed in terms of dept h underestimation of isolated surfaces, depth enhancement, depth contr ast, and the processing of deformation disparity.