Part II Conclusion Interdisciplinary roots of Lewin’s theory of human conduct 93
8.2 Types of experiments
8.2.1 Perception
Paper-and-pencil experiments on Gestalt perception
The largest group of Gestalt experiments was designed asstructured phenomenological observations.
Predominantly, these were carefully constructed attempts to grasp the principles of self-organization of the so-called "good phenomena”. Observers were allowed to experience a “whole situation” instead of being asked to fixate on a single point or stimulus array, as in experiments conducted by other psycho-logical schools. A range of uncomplicated paper-and-pencil studies was devised under the instruction of Wertheimer to demonstrate the perception of “good phenomena”. The observers’ perception of lines, dots and filled regions on a page of paper was tested (exemplary studies were outlined in section 3.2). To mention one example, an experimental study of the brightness contrast was devised by Wertheimer and pursued by Wilhelm Benary, a former collaborator of Kurt Goldstein and Köhler’s assistant since 1923, and Wolfgang Metzger in Berlin. Benary’s “cross-triangle experiment” combined two identical gray tri-angles with a bigger black cross. Both tritri-angles were surrounded by one black and two white sides (fig.
11). However, observers identified the triangle located inside the larger black figure as brighter than the one outside the cross. The Gestalt interpretation was that the two gray triangles are perceived differently because one appeared to belong to the cross and the other did not (“law of belongingness”).314
Figure 11: Benary cross after [Benary, 1924, 131]
Experiments on the “whole field”
One of the most spectacular demonstrations of perceptual organization resembled to an impressive light installation and came from research that the Berlin associates Willy Engel, Wolfgang Metzger and Walter Jablonski published in 1930. A projector with a specially designed set of lenses was set up in one of the
312F. R. Meier on Wertheimer in [Luchins and Luchins, 1986, 14].
313Cf. Norman Meier in [Luchins and Luchins, 1986, 14f.].
314Cf. [Benary, 1924, esp. 131f.], see also [Metzger, 1931, 374-386].
institute’s high-ceilinged rooms. This casted light at an 80°angle from a high tower toward a white wall surface of four meters squared. Screens extending from the wall were lit so that their edges would not be seen. Another screen reached from the top of the wall above up to a zone behind the proband (see fig. 12).315 As the illumination gradually faded, observers saw first a somewhat concave surface, then a fog, which after some time became a foggy mass approaching them through space. In Metzger’s words, the observer’s experience was that of a total disappearance of space around her or him.
“It is and an extremely unpleasant experience, similar to dizziness. The room literally sucks itself around the observer; a kind of disappearance of the environment is experienced, not just an indifferent reformation. The eyes automatically seek something solid, a resting point that could prevent the disappearance” [Metzger 1930].316
Figure 12: Sketch of the projection technique [Engel 1930, 2]
The Gestalt psychologists called this special environment a “whole field” (Ganzfeld), in which, Met-zger argued, color and illumination could not be clearly separated.317 In a variation of theGanzfeld -experiment Jablonski attempted to grasp the conditions under which complementary after-images ap-peared in short-term color projections.318 The perception experiments in theGanzfeld seemed to docu-ment holistic experience in its most pure shape. Perception experiences that deviated from those doc-umented in a “field segment” (Teilfeld) were of particular interest. The Gestalt psychologists used their observations from experiments on the whole field to confirm and extend Wertheimer’s original principles of Gestalt organization.
8.2.2 Quantifiable invariant relations
Another type of experiments came close to natural science, i.e. its substance consisted in the identifica-tion ofquantifiable invariant relations in the mental realm. The existence of such invariant relations within and across sense modalities was considered the essence of Wertheimer’s laws. Experiments set up to provide evidence employed then-standard experimental techniques as well as quantitative inferences from parametric or threshold measurements.
315Engel presents a detailed documentation of the the experimental scenery, [Engel, 1930, 1-5].
316“Die Raumbegrenzung plötzlich ganz anschaulich sich auflösen zu sehen, ist ein ausgesprochen unangenehmes Erleb-nis, schwindelartig: Der Raum saugt sich förmlich um den Beobachter; eine Art Schwund der Umwelt wird erlebt, nicht eine gleichgültige Umformung. Die Augen suchen unwillkürlich nach etwas Festem, einem Haltepunkt, der den Schwund verhindert”
[Metzger, 1930, 9].
317Cf. [Metzger, 1930, 6f.].
318See [Jablonski, 1930, 145-197].
Sound localization
For instance, Max Wertheimer and Erich von Hornbostel re-utilized the instrument they had invented to predict the direction of artillery and torpedo fire for studies of sound localization (akustische Rich-tungswahrnehmung). They challenged widely held views that sound localization was derived from the intensity of the perceived sounds or from phase differences in acoustic stimulation.319 Hornbostel’s and Wertheimer’s experiment set up knock sounds that were intensified and steered by means of two micro-phones or funnels as time intervals and directions were modified. At the end they found that "the angle at which a sound is heard is lawfully dependent on the time difference with which the same stimulus im-pacts each of the ears”.320 Specifically, the angle of subjective localization increased with the deviation from simultaneity, reaching 90° at 630 microseconds; just noticeable differences are greatest near the median, and decrease as the angle approaches 90° (cf. ebd. 389). This experimental study meant to show that such phenomena as the localization of sound were determined in a centralized physiological process (cf. ebd. esp. 395f.).
8.2.3 Psycho-physiological Gestalt correlates Successive comparisons across sense modalities
The third type of experiments was part of Köhler’s and Goldstein’s search for physiologicalGestalten.
Experiments intended to show that the physiological correlates ofGestaltencould underlie brain events.
For instance, Köhler attempted to create a new model of experimental procedures to prove his theory of brain processes (i.e. the existence of physiological correlates to psychological phenomena).321 He stud-ied the judgement of the loudness of sounds in ascending and descending sequences. Using a double sound pendulum (Schallpendell) he made his probands listen to pairs of clicks of slightly different inten-sity (see fig. 13).322 He then found that objectively equal tones are more often perceived to be different in ascending than in descending series of clicks. Similar observations (that seemed to have inspired Köhler) have been made by J. Borak. His study of lifted weights showed that probands noted minor dif-ferences between weights more easily when they lifted the lighter of the two weights first.323 Additionally, corresponding observations on successive comparisons were made in the framework of the early inves-tigations in psychophysics.324 Invoking the strikingly correspondent observation across different sense modalities Köhler suggested that they are of a general nature, and that only processes in the nervous system could do justice to the dynamics at work. His hypothesis was that initial impressions of sound, light, weight and so fourth leave “quiet pictures” (stille Bilder) in the form of energy or electrochemical distributions in the specific region of the cortex, which undergo structural changes as the comparison proceeds. While the contemporary knowledge of the brain was not sufficient to conclusively verify the hypothesis the Gestalt psychologists suggested to approach the neurological investigation from the side of the psychological facts.325
319These theories were advanced e.g. by Myers and Wilson, [Myers and Wilson, 1908, 260-66].
320“Alle bisher mitgeteilten Versuchsergebnisse sprechen dafür, daß der Seitenwinkel, in dem ein Schall gehört wird, gesetzmäßig abhängig ist von dem Zeitunterschied, mit dem der gleiche Reiz auf das eine und andere Ohr wirkt.”
[von Hornbostel and Wertheimer, 1920, 391].
321Remarkably, while psychology of the 1920s lacked the instruments to prove or disprove the existence of neural correlates of subjective phenomena modern neuroscience verify Köhler’s theory. In the late 1930s, working at Swarthmore College in the laboratory of his own design, Köhler eventually received the opportunity to use the newly developed EEG equipment (electroen-cephalograph), by means of which he was able to verify the existence of his anticipated brain correlates. Cf [Köhler, 1940, 193];
see Chapter 11.
322The illustration of the double sound pendulum (Schallpendel) originates from [Hoyer and Spindler, 1908, 0104]. It was re-produced in the Max Planck Virtual Laboratory: http://vlp.mpiwg-berlin.mpg.de/library/data/lit24062/index_html?pn=109, 23 June 2014.
323See [Borak, 1922, 374-389].
324Results similar to Köhler’s have been published: amongst others, on sound intensity, cf. [Starke and Paul, 1886, Starke, 1889, Angell, 1892]. On pressure intensity, cf. [Stratton, 1896].
325Cf. [Köhler, 1923, espec. 120, 148f., 166ff.]; cf. also [von Hornbostel and Wertheimer, 1920, 396].
Figure 13: Double sound pendulum (Schallpendel), 1908.