A group of early experimental psychologists known as Gestalt psychologists believed that perceptions are more than the stimuli that create them. By more is meant that a meaningful, whole pattern is created by the stimuli (that is, the total is more than the sum of its parts). These psychologists developed the idea, the principle of Prägnanz, that stimuli can be grouped and seen as a whole. These psychologists believed that the innate, organizing tendencies of the brain would explain organization functions in perception, including many optical illusions, for example, the phi phenomenon and certain figure‐ground relationships.
The phi phenomenon occurs when you see two adjacent lights alternately blinking off and on and perceive them as one light moving back and forth. This phi phenomenon illusion is frequently used in signs to suggest movement.
Figure (object)‐ground (background) relationships are important in Gestalt theory, which suggests that perceptions are organized to produce a figure‐ground effect. One tends to see objects against backgrounds rather than to view each separately. However, when instructed, one may reverse the relationship and see the object as background and vice versa. In the famous figure‐ground illustration shown in Figure , do you see a goblet or the profile of two faces?
A Figure‐Ground Illustration