The Story of Psychology (56 page)

FIGURE 5
The Law of Similarity: a simple example

The similarity factor can, in fact, overcome the proximity factor. In the left-hand box below, we tend to see four groups of closely spaced objects; in the right-hand box, two sets of dispersed but similar objects.

FIGURE 6
The Law of Similarity: a more complex example

Continuation or direction:
In many patterns, we tend to see lines that have a coherent continuation or direction; this is why we are able to pick out a meaningful shape from a bewildering background, as we do in “hidden figure” puzzles. Such a line or shape is a “good Gestalt”—one with inner coherence or inner necessity. In this pattern, for instance,
we can force ourselves to see two curved pointed figures, AB and CD, but what we tend to see is the more natural Gestalt of two intersecting curves, AC and BD. The factor of continuation can be astonishingly powerful. Consider these figures—

FIGURE 7
The Law of Continuation: two curves or two pointed shapes?

FIGURE 8
Two figures, easily seen as distinct

and now this one, a merger of the previous two:

FIGURE 9
The same figures, now visually inseparable

It is virtually impossible to see the originals in the merged figure because of the dominance of the continuous wavy line.

Prägnanz:
The related English word “pregnancy” does not convey Wertheimer’s meaning, which is “the tendency to see the simplest shape.” Much as physical laws cause a soap bubble to assume the simplest possible shape, so the mind tends to see the simplest Gestalten in complex patterns. This figure

FIGURE 10
The Law of Prägnanz: We see the simplest possible shapes.

could be interpreted as an ellipse with a right-angled segment cut out of the right side of it touching a rectangle with a curved chunk cut out of the left side of it. But that is not what we see; we see the far simpler image of a whole ellipse and a whole rectangle overlapping.

Closure:
This is a special and important case of the Law of
Prägnanz.
When we see a familiar or coherent pattern with some missing parts, we fill them in and perceive the simplest and best Gestalt. We see this as a star instead of the five V’s that make it up.

FIGURE 11
The Law of Closure: We supply what is missing.

In the 1920s, the Gestalt psychologist Kurt Lewin noticed that a waiter could easily remember the details of a customer’s bill if it had not yet been paid, but as soon as it was paid he forgot the details. It occurred to him that this was an instance of closure in the area of memory and motivation. As long as the transaction was incomplete, it lacked closure and generated tension, maintaining memory, but as soon as closure was achieved, the tension and the memory disappeared.
¹³

A student of Lewin’s, a Russian psychologist named Bluma Zeigarnik, put his conjecture to the test in a well-known experiment. She assigned a number of volunteers a series of simple tasks—making clay figures, solving arithmetic problems—allowing them to complete some of the tasks but interrupting them during others on a pretext and not letting them finish the work. A few hours later, when she asked them to recall the tasks, they remembered the uncompleted ones about twice as well as the completed ones, confirming Lewin’s guess.
¹⁴
The study made her famous, in a small way; to this day, psychologists writing about motivation refer to the “Zeigarnik effect.”

Figure-ground perception:
When we pay attention to an object, we see little or nothing of the background; we see the face we are looking at, not the room or landscape beyond it. In 1915 Edgar Rubin, a psychologist
at the University of Göttingen, explored this “figure-ground” phenomenon—the mind’s ability to focus attention on a meaningful pattern and ignore the rest of the data. He used a number of test patterns, one of which, the so-called Rubin vase, is familiar to almost everyone:

FIGURE 12
The Rubin vase: Pottery or profiles?

If you look at the vase, you do not see the background; if you look at the background—two faces in profile—you do not see the vase. Moreover, you can
will
yourself to see whichever you choose; will apparently does exist, in spite of the New Psychologists and the behaviorists.

Size constancy:
An object of known size, when far off, projects a tiny image on the retina, yet we sense its real size. How do we manage that? Associationists said that we learn from experience that remote objects look small and pale, and we associate these clues with distance. Gestaltists found this explanation simplistic and contrary to new evidence. Very young chicks were trained to peck only at larger grains of feed. When the habit was firmly established, the larger grains were put at a distance, where they looked smaller than the nearby small grains, but the chicks unhesitatingly went for the larger ones. An eleven-month-old baby girl was trained (by means of a reward) to choose the larger of two side-by-side boxes. The larger box was then moved far
enough away for its retinal image to be only 1/15 the area of the smaller box, but she still chose it.
¹⁵

We sense that distant objects are as large as when they are near because of the mind’s organization of data in terms of relationships—to adjoining known objects, for instance, or to perspective-giving features.
¹⁶
The two illustrations in Figure 13, from a relatively recent textbook of perception, make the point:

FIGURE 13
Perspective gives clues to size.

In the left-hand panel, the relationship of the farther man to things near him and to the hallway enables us to perceive him as being as large as the nearer man. Yet on one’s retina the image of the farther man is very much smaller, as the right-hand panel shows.

Sultan, a male chimpanzee living in an anthropoid research center, has had nothing to eat all morning and he is hungry. His keeper lets him into a room where a bunch of bananas is hanging from the ceiling, out of reach. Sultan jumps toward the bananas a few times but comes nowhere near them. He then prowls around the cage, making discontented sounds. Some distance from where the bananas are hanging he comes upon a short stick and a large wooden box. He picks up the stick and tries to knock the bananas down, but they are too high. For a while, he bounces around
,
upset and angry; then, he suddenly rushes to the box, pulls it under the bananas, climbs up on it, and with a little jump seizes his prize.