psychology (also Gestalt theory of the Berlin School) is a theory of mind and brain that proposes that the operational principle of the brain is holistic, parallel, and analog, with self-organizing tendencies. The classic Gestalt example is a soap bubble, whose spherical shape (its Gestalt) is not defined by a rigid template, or a mathematical formula, but rather it emerges spontaneously by the parallel action of surface tension acting at all points in the surface simultaneously. This is in contrast to the "atomistic" principle of operation of the digital computer, where every computation is broken down into a sequence of simple steps, each of which is computed independently of the problem as a whole. The Gestalt effect refers to the form-forming capability of our senses, particularly with respect to the visual recognition of figures and whole forms instead of just a collection of simple lines and curves.
The key properties of Gestalt systems are emergence, reification, multistability, and invariance.
Emergence is demonstrated by the perception of the Dog Picture, which depicts a Dalmatian dog sniffing the ground in the shade of overhanging trees. The dog is not recognized by first identifying its parts (feet, ears, nose, tail, etc.), and then inferring the dog from those component parts. Instead, the dog is perceived as a whole, all at once.
Reification is the constructive or generative aspect of perception, by which the experienced percept contains more explicit spatial information than the sensory stimulus on which it is based.
For instance, a triangle will be perceived in picture A, although no triangle has actually been drawn. In pictures B and D the eye will recognise disparate shapes as "belonging" to a single shape, in C a complete three-dimensional shape is seen, where in actuality no such thing is drawn.
Multistability (or Multistable perception) is the tendency of ambiguous perceptual experiences to pop back and forth unstably between two or more alternative interpretations. This is seen for example in the Necker cube, and in Rubin's Figure / Vase illusion shown to the right. Other examples include the 'three-pronged widget' and artist M.C. Escher's artwork and the appearance of flashing marquee lights moving first one direction and then suddenly the other.
Invariance is the property of perception whereby simple geometrical objects are recognized independent of rotation, translation, and scale; as well as several other variations such as elastic deformations, different lighting, and different component features. For example, the objects in A in the figure are all immediately recognized as the same basic shape, which are immediately distinguishable from the forms in B. They are even recognized despite perspective and elastic deformations as in C, and when depicted using different graphic elements as in D.
Web-based forums and email providers rely on invariance of human perception to prevent automated bots from exploiting the services. A CAPTCHA test presents a distorted image of letters and numbers, not readable by computers, and prompts user to correctly type the string.
Emergence, reification, multistability, and invariance are not separable modules to be modeled individually, but they are different aspects of a single unified dynamic mechanism.
The investigations developed at the beginning of the 20th century, based on traditional scientific methodology, divided the object of study into a set of elements that could be analyzed separately with the objective of reducing the complexity of this object. Contrary to this methodology, the school of Gestalt practiced a series of theoretical and methodological principles that attempted to redefine the approach to psychological research.
The theoretical principles are the following:
- Principle of Totality - The conscious experience must be considered globally (by taking into account all the physical and mental aspects of the individual simultaneously) because the nature of the mind demands that each component be considered as part of a system of dynamic relationships.
- Principle of psychophysicalisomorphism - A correlation exists between conscious experience and cerebral activity.
Based on the principles above the following methodological principles are defined:
- Phenomenon Experimental Analysis - In relation to the Totality Principle any psychological research should take as a starting point phenomena and not be solely focused on sensory qualities.
- Biotic Experiment - The School of Gestalt established a need to conduct real experiments which sharply contrasted with and opposed classic laboratory experiments. This signified experimenting in natural situations, developed in real conditions, in which it would be possible to reproduce, with higher fidelity, what would be habitual for a subject.
The most basic rule of gestalt is the law of prägnanz. This law says that we try to experience things in as good a gestalt way as possible. In this sense, "good" can mean several things, such as regular, orderly, simplistic, symmetrical, etc. The other gestalt laws are:
- Law of Closure - Our mind adds missing elements to complete a figure.
- Law of Similarity - Our mind groups similar elements to an entity. The similarity depends on relationships constructed about form, color, size and brightness of the elements.
- Law of Proximity - Regional or chronological closeness of elements are grouped by our mind and seen as belonging together.
- Law of Symmetry - Symmetrical images are seen as belonging together regardless of their distance.
- Law of Continuity - The mind continues a pattern, even after it stops.
- Law of Common Fate - Elements with the same moving direction are seen as a unit
Figure-ground minds have an innate tendency to perceive one aspect of an event as the figure or foreground and the other as the ground or the background.
Under the gestalt theory, these laws not only apply to images, but to thought processes, memories, and our understanding of time.
Examples of the Gestalt experience include the perception of an incomplete circle as a whole or a pattern of dots as a shape - the mind completes the missing pieces through extrapolation. Studies also indicate that simple elements/compositions where the meaning is directly perceived do not offer as much a challenge to the mind as complex ones and hence the latter are preferred over the former.