However, we do tend to see alternating columns of circles and squares. This, the Gestalt psychologists would argue, is because of the principle of similarity - features which look similar are associated . A third principle of perceptual organization is that of good continuity . This principle is that contours based on smooth continuity are preferred to abrupt changes of direction . A fifth principle of perceptual organization is that of smallness .
Smaller areas tend to be seen as figures against a larger background .
In the figure below we are more likely to see a black cross rather than a white cross within the circle because of this principle. The lower portion of the illustration below offers negative image versions in case this may play a part. To avoid implicating the surroundedness principle I have removed the conventional broad borders from the four versions. The Gestalt principle of smallness would suggest that it should be easier to see the vase rather than the faces in the two versions on the left below. The principle of symmetry is that symmetrical areas tend to be seen as figures against asymmetrical backgrounds .