Perceptual grouping produced by changes in orientation and shape.

The relative effectiveness of changes in orientation and shape in producing perceptual grouping has been stuidied using a method based on threshold judgments. Statistical analyses of the threshold vallues show that rotating some of the figures in afield from a vertical position to a slant of 45 degrees facilitates segregating the field into separate perceptual groups. In contrast, changes in the shape or orientation of these figures, which leave their component lines vertical and hlorizontal, do not reliably aid grouipinig. The results also suggest that the simli-larity of the figures comtposing the field is not a good predictor of the degree to which the figures will cohere to form distinct perceptual groups.