Gestalt Psychology and Cognitive Psychology

The aim of this paper is to sketch the major aspects of Gestaltpsychologie: Wertheimer‘s factors, global v. local factors, isomorphism, auto-organisation, Prägnanz as singularity and as a tendency towards stability. While Gestaltpsychologie as a school no longer exists, its lesson is yet seminal and can inspire many developments of contemporary cognitive psychology. Few examples are here illustrated: geometric psychology, non linear systems (mainly synergetics), and computational gestalts. 1. The Characteristics of Gestaltpsychologie It is almost trivial saying that Gestalt psychology has been the most consistent and successful psychological school developed in the past century in Europe as a reaction against elementism and associationism, typical of the beginning of scientific psychology in the last decades of XIX century. As a school, after the death of its principal exponents (Wertheimer, Köhler, Koffka) the Gestalt psychology, doesn‘t exist anymore. Nevertheless, the lesson of this psychological school is such that still today it cannot be ignored, at least by students of perception and thinking. In the same time, the ideas of Gestalt psychologists were very often misunderstood, and this has given room to several mistakes and wrong interpretations. In this paper first I will try to point out, beyond trivialities and misunderstandings, which actually were the main issues of Gestalt psychology that determined a real turning-point in the history of psychology of this century. It is important to identify this, as distinguished from the main * Dipartimento di Psicologia ―Gaetano Kanizsa‖, Università degli Studi di Trieste, Italy. 96 Humana.Mente — Issue 17 — July 2011 misunderstandings that, overall through a number of misinterpretations by American psychologists, have followed the diffusion of Gestaltist concepts. One must in any case point out that these misunderstandings have been sometimes facilitated by some theoretical weakness of Gestalt psychologists. However, we will see how Gestaltist ideas have deeply influenced contemporary cognitive psychology, and how such influence has been particularly evident in the last years. At the beginning of the so-called ―cognitive revolution‖, there were several attempts to translate Gestalt ideas in terms of information theory (Attneave, 1954, 1959; Garner, 1962). After these attempts, which have only a historical interest today, other approaches emerged. Specifically, I will sketch three examples of them, showing first the place of a very important metaphor, like the concept of field, in contemporary theorising about perceptual invariance, above all in the so-called ―geometric psychology‖ developed by Hoffman (1966, 1977, 1984); second, we will see how the theory of dynamic formation and recognition of pattern, as elaborated in the framework of synergetics by Haken (1990; cf. Kelso, Ding, & Schöner, 1992; Kelso, 1995) can be seen as a natural development of Gestalt ideas; third, I will present in short the major ideas developed in the field of computer vision under the name of ―computational gestalts‖ (for a comprehensive review, see Desolneux, Moisan, & Morel, 2006). It is obvious that it is absolutely impossible synthesizng the essential ideas of Gestalt psychology in few pages. Thus, I will confine myself to few basic ideas developed by this school. 2. Wertheimer‘s Factors of Perceptual Organisation The first point I want to clarify is the relationships between whole and parts. It is well known that Wertheimer (1923) stressed the importance of the von oben nach unten processing in perceptual organisation. With this expression, he claimed that the global configuration has a prevalence on the parts that compose a totality. The psychology most influential at the time in which Gestalt psychology appeared, the wundtian psychology, claimed the opposite way of organisational processing, von unten nach oben. This opposite way was what Wertheimer called a ―summing up‖ of parts, leading to a ―mosaic‖ perception. It is unfortunate that the English translation of the above expressions, respectively top down and bottom up, has assumed in cognitive psychology a Gestalt Psychology and Cognitive Psychology 97 quite different meaning: top down is considered equivalent to concept driven, and bottom up to sense driven. However, both directions of processing were, according to Wertheimer, sense driven (Kanizsa & Luccio, 1987). In other words, according to Gestalt psychology all perceptual organisation depends only on ―autochthonous‖ factors, that is, on factors that are all in the stimulus, thereby they do not depend on previous knowledge, expectancies, voluntary sets, intentions of the observer. But what means exactly nach oben von unten? Simply, the meaning of the parts is determined von oben nach unten, by the whole to which they belong. An apt example is the famous research of Wertheimer (1912a) on stroboscopic movement. He presented to his observers two lines, before the vertical one, and after switching off this, the horizontal one. With suitable interstimuli intervals, the observer viewed only one line, moving from vertical to horizontal, and vice versa. Two points must be stressed: first, the global situation created an identity between the two lines, that now were one thing; second, in the physical situation there was no movement at all, from a physical point of view: again, the global situation created nach oben von unten an apparent motion, that, with suitable conditions of stimulation, could be isolated from the moving object (phi phenomenon). From the above point of view, it is thus easier to understand the very meaning of the so-called ―laws‖ (better, principles or factors) stated by Wertheimer (1922, 1923), ruling the formation of perceptual forms. Let us review briefly these laws, bearing in mind the importance of the von oben nach unten principle of perceptual processing. According to Wertheimer, when an observer is presented a perceptual field, and he looks at it in an absolutely natural way, without any effort and any scrutiny, the field segregates itself in different perceptual units, constituted by the elements present in the field, which tend to aggregate themselves according to certain factors. These are (i) proximity, (ii) similarity, (iii) continuity of direction, or good curve, (iv) common fate, (v) past experience, and (vi) Prägnanz. All these factors are well known, but let‘s discuss shortly the last two. It is not easy to explain what Wertheimer meant for past experience, because Gestalt psychologists used this expression to indicate something of quite different from what was meant in traditional empiricist tradition (till today, in the neo-helmholtzian theorising). According to Gestalt pyschologists, nor past experience neither more generally evolution (Köhler, 1950) can alter the 98 Humana.Mente — Issue 17 — July 2011 general principles of perception, which are a consequence of the physical properties of the neural substratum. They claimed that brain is a physical system ruled by physical laws, which cannot be modified; only the constraints in which the dynamics of the system can evolve. The principle of Prägnanz is the most widely accepted among cognitive psychologists, and many attempts were made to formulate it in other terms, for example, in terms of information theory (Attneave, 1959; Garner, 1962). The principle states that there is a tendency towards the formation of Gestalts which are maximally regular, simple, symmetric — ausgezeichnet, according to Wertheimer‘s term; ―good‖, as they are often said. As Kanizsa & Luccio (1986) pointed out, however, the term Prägnanz is defined ambiguously, as a characteristic of a percept, and as a process; and as a multidimensional attribute (as in Rausch, 1966) or as a point of discontinuity, singular (as in Goldmeier, 1982). This point will be discussed at length below. 3. Physical Gestalten and the Concept of Field Among the several metaphors that Gestalt psychology utilised in describing the dynamics of cognitive processes, the concept of ―field‖ (and related ―field forces‖) has been the most celebrated, and in the same time the most widely criticised. This concept was elaborated mainly by Wolfgang Köhler; the first idea can be found, however, in the ―transversal flows‖ hypothesised by Wertheimer (1912b). In Köhler‘s opinion (1920), in the physical world one can observe several different systems that tend to evolve dynamically, according to a minimum principle, towards a state of equilibrium, in which the energetic level is as low as possible. The prototypical example of such a ―physical Gestalt‖ is given by soap bubbles. The brain is one such system, and his functioning can be well described in terms of electric states evolving in the nervous matter. Köhler (1940) supposed that within the brain electric fields act, and he suggested as a basis of these fields the action of chemical mediators; the figural after-effect and other perceptual phenomena fitted very well to this model, that in Köhler‘s days was plausible. Wolfgang Köhler fully developed Wertheimer‘s insight in his book ―Die physischen Gestalten in Ruhe und im stationaren Zustand‖ [Physical Gestalten in rest and in stationary state]. Köhler wrote the book when he was in Tenerife, Gestalt Psychology and Cognitive Psychology 99 Canary Islands, during the First World War, studying apes. As Köhler (1969) remember, when he was in Tenerife, he read the great ―Treatise on Electricity and Magnetism‖ written fifty years before by J. Clerk Maxwell (1881), and he was ―great relieved to find so fundamentally similar an approach‖ (Köhler, 1969, p. 75) between great physicists, like Maxwell, or Max Plank (Köhler had been a student of him), or Kirchoff, or Eddington, and Gestalt psychologists. One must add that in Köhler‘s book was obvious the influence of another eminent physicist, Ernst Mach. The book is complex, and it is almost impossible to sketch here an account of it. We will confine ourselves only to a glance on its content. We recall that von Ehrenfels (1890) had defined suprasummativity (the parts are ―poorer‖ than the whole, in Köhler‘s words) and transposition as key concepts for Gestaltqualitäten. The point of departure of Köhler consists in individuating the same properties in an electric field, that is, in the distribution of electric charges around a conductor. The second step is to hypotesize that, in the brain, there are chemo-physical fields having the same properties. The final step is individuating the same system properties [Systemeigenschaften] in domains, the experience (the phenomenal field) and the brain. In particular, according to Köhler there are four properties that are similar in phenomenal and in brain fields: (1) the total processes appear in both fields as units with dynamic properties: (2) in both the unity is compatible with a structured articulation [Gliederung] of the component parts: (3) in both one can individuate gradients because of the distance from one region to another that consent to consider the regions as independent from the ones that are faraway: (4) in both we can individuate limited regions (Gestalten, in the phenomenal field) on a ground. Essentially, then, the perceptual field is a physical system, a system of interacting forces, in which any object that enters modifies the equilibrium of the forces, and thus acts over any other object that is present in the field. The evolution towards this optimal level corresponds to the tendency towards the Prägnanz. The best attempt to render this metaphor less vague was made by Brown & Voth (1937). They describe the visual field as a spatial construct to which the phenomena of visual experience are ordered, with differences in intensity at various loci. The structure of the field is the configuration, or ―gestalt‖, of the intensity distributions within it. It is a vector field, and the dynamic processes within it are produced by field-forces. It can be thought of 100 Humana.Mente — Issue 17 — July 2011 as a four-dimensional manifold, having three spatial and one temporal dimension. Brown and Voth hypothesise two kinds of forces, having the nature of vectors: cohesive and restraining field-forces. The cohesive forces C attract objects, the restraining forces R tend to maintain them in their place. Physiologically, the cohesive forces are largely peripheral, retinallyconditioned, while the restraining ones are centrally-conditioned. The cohesive forces allow to explain the phenomena of motion and grouping, the restraining ones the phenomena of stability of contours, figural properties of objects, etc. Brown and Voth have successfully tested their model in experiments on perception of real and apparent motion. Orbison (1939) has extended it in the case of stationary configurations. According to Orbison, if two objects are brought into the visual field, they will be acted upon the cohesive and restraining forces whose magnitudes are functions of the physical properties of the stimulus pattern. To test this model, Orbison has created several geometrical figures (called geometrical fields). The work by Brown and Voth and by Orbison was mainly at the phenomenological level, and the physiological level was not worked out. The physiological counterpart of the phenomenal level was the one above mentioned elaborated by Köhler. One must mention that Köhler had stated the principle of the isomorphism, according to which there is a structural correspondence between what occurs at the physiological level and what happens in the phenomenal field, a mapping on the events of a level onto the other. This principle will be discussed below. Lashley, Chow, & Semmes (1951) and Sperry, Miner, & Myers (1955) tried to test Köhler‘s neurophysiological theory, but their results led to a rejection of the field theory. It is fair to add that Köhler (1958) raised serious objections against these experiments, without receiving any answer. The scientific community of psychologists accepted, very superficially indeed, as decisive such counter demonstrations, and this was the end of the brain field theory. Gestalt Psychology and Cognitive Psychology 101 4. Is Gestaltheorie a Representational Theory? The most influential author that was at the beginning of the antiassociationist reaction in the XIX century was Franz Brentano, with his writings (Psychologie [1874] was one of the most seminal books of all the century) and his teaching: notice that among his pupils we can list Meinong, Marty, von Ehrenfels, Stumpf. Wertheimer was a student of Marty and von Ehrenfels in Prague; it is well known that all major Gestalt psychologists were directly pupils of Carl Stumpf in Berlin: Wertheimer, Köhler, Koffka, Lewin. In other terms, they did not have any direct contact with Brentano (that resigned from teaching in 1895, before the beginning of studying of all of them). Brentano was strongly anti-elementist: according to him, there are no psychological elements but only psychical acts, which could be distinguished in three fundamental kinds, to whom experience is reducible: representation (ideating), judgment, and loving-hating (feeling). And it is equally well known that the very first use of the term Gestalt in the technical sense in psychology is due to von Ehrenfels, in his celebrated paper on Gestaltqualitäten (1890). So, in many textbooks of history of psychology the trivial equation is ready made: Gestalt psychology derives directly from Brentano, via the concept of Gestalt introduced by von Ehrenfels, and the teaching of Stumpf upon his leading exponents. This equation, however, is too simple, and in many respects it is misleading. It is very rare to find quotations of Brentano in the papers of Wertheimer and associates, and when this happens it is mainly done to distinguish the position of Gestaltists from the one of Brentano. A crucial difference between Brentano‘s and Gestalt ideas concerns the very representational nature of his psychology. A point that originated a great deal of debate on the turning of the century is the ―intentional inexistence‖ of the psychicalwhich differentiates it from the physical. Brentano derives this concept from the Scholastics of the Middle Ages, for whom intentional inexistence had to be understood as immanent objectivity (for a discussion of intentional inexistence, and of the consequences of the introduction of this concept on the semantic debate in our century, see Coffa, 1989). So, psychical acts were phenomena that intentionally contained an object; this immanent objectivity uniquely distinguishes them from the physical phenomena that they ―intend‖. 102 Humana.Mente — Issue 17 — July 2011 In my opinion, the very idea of ―representation‖ is alien to Gestaltpsychologie (see also Luccio, 2010). We can ask to ourselves why, if Gestalttheorie is a representational theory, the authors almost never use the term ―representation‖, or its many German synonyms (contra, see Lehar, 2003a, 2003b; Scheerer, 1994). And one could use it safely in different contexts, also without any theoretical commitment to a representational theory. But also there, the Gestalt psychologists preferred other terms. For instance, in the paper on thinking of primitive peoples, referring to the mental constructs of numerical structures, Wertheimer (1912a) prefers to speak of Gebilde. Note that according to Lehar, Gestalt theory is a representationalist theory qua perceptual theory. According to Scheerer, the very fact that we believe in a transphenomenal word is sufficient to argue that our cognitive system is representational. I do not think that to call the mediating brain processes ―representations‖ is correct, because to speak about representations, I must be aware of them. Gestalttheorie rejects the idea of representation, or, at most we can say that the Gestalt authors had an indifferentist stance on this problem (Luccio, 2003b). For them, the contents of the directly accessible world do not stay for something else, as ―representation‖ would imply, but stay for the contents themselves. Here, it is important to stress the difference that Köhler proposes between subjective and objective experiences, both ―results of organic processes‖ (Köhler, 1947, p. 23), when the subjective experiences are the contents of the phenomenal world that are felt as belonging personally to the subject, and are in so far subjective, such a dreadful fear upon a certain occasion [...] For instance, a chair as an objective experience will be something there outside, hard, stable, and heavy. Under no circumstances will it be something merely perceived, or in any sense a subjective phenomenon. (Köhler 1947, pp. 20–21) Still clearer is Wolfgang Metzger (1941, c. 2.), in his classic treatment of the psychic reality [seelisch Wirklichen]. According to Metzger, the first distinction that one must perform is between the physical or metaempirical world [physikalische oder erlebnisjenseitig Welt] and the phenomenal or lived world [anschauliche oder erlebte Welt]. These are the first and second meanings of psychic reality, and according to Metzger in psychology there is Gestalt Psychology and Cognitive Psychology 103 often confusion between these two meanings. But there is another dangerous confusion that often occurs, and it is between the second meaning and a third, the represented world [vergegenwärtigte Welt]. The real world in the second meaning has the characteristics of the ―met‖ [Angetroffene]. The met things, events, actions, beings, are a reality of things, events, actions, beings as such, while when represented are felt completely different, as ―pointing to‖ [hinweisend auf] another reality.