Laws of Pragnanz

Kohler, one of the influential Gestalt psychologists, described laws of pragnanz that, he said, determined which gestalts would be formed from ambiguous stimuli. In German, pragnanz means clarity, so laws of pragnanz are laws of clarity. The most common translation is laws of good form. A law of pragnanz identifies an organizational tendency, a way in which the human brain decides that things go together.

What does "pragnanz" mean? What are the principles or laws of similarity, proximity, continuity, and closure?

One of Kohler's laws of pragnanz involved similarity. Similarity among components encourages an observer to organize them into a figure. Proximity is another law of pragnanz mentioned by Kohler. Proximity is closeness. Objects close to each other tend to be perceived together in one form or gestalt.


In order from left to right: closure, symmetry, continuity, similarity, and proximity.

In the first illustration, one can see a rider on a horse despite the fact that major portions of the figure are missing. This is called closure because the perceptual system closes the gaps automatically. The second example—the triangle behind the ball—illustrates the effect of symmetry and also continuity (symmetry is present because the left and right halves of the triangle are mirror images of each other; continuity is illustrated because we assume the bottom edge of the triangle continues behind the ball). The third example, the broken circle, illustrates continuity. The elements are seen as a circle rather than just line segments, because the segments are lined up in a continuous curve. The same figure illustrates closure because the continuity encourages us to fill in the gaps and see a circle. The fourth example shows similarity, because we group similar items together and tend to see four columns rather than four rows. The fifth and last example shows the law of proximity or closeness, because it is easier to see four rows rather than four columns when the elements are so close together.

Why is "closure" useful?


A famous demonstration of "closure"

The dog with his nose to the ground is a famous example of closure. When you see the dog, it suddenly becomes solid. A gestalt is formed. Your perceptual system succeeds in connecting the pieces (closing the gaps, so to speak) and you perceive an object.

Our perceptual systems need this ability because often our view is partially blocked or obscured. Without closure, we could not recognize objects seen through a bush or a rainy window, or when other objects blocked part of our view. Because of the visual system's ability to create closure, humans are very good at creating a gestalt or perceptual object out of the mere suggestion of an object.


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