Lecture
The demonstration experiment (study) is contrasted with the control experiment, because in it, upon obtaining negative results, one cannot proceed to an evaluation of the control group.
That is, here there is no stage of making a decision about the experimental fact, because there is no choice between the alternatives «for» and «against».
The two best-known types of demonstration studies are:
1. The initiation of effects that are practically unambiguously reproducible in an analogous situation. The expected effect here is 100%. Such studies include the demonstration of perceptual phenomena. A white screen and the projection of monochromatic colors onto it, the mixing of colors – yield unambiguous results for any researcher (we do not take color-anomalous individuals as participants).
In the most basic process being subjected to «manifestation», there are no changes.
1. This type can unambiguously demonstrate the correctness or adequacy of a psychological hypothesis only in relation to an event that has already occurred. These are usually phenomena connected with motivation, volitional regulation, and group dynamics. They cannot be reproduced exactly a second time, because the actual genesis depends on the subject.
Example: Lewin's studies and the problem of their reproducibility.
A situation with a special structure made it possible to provoke the manifestation of dynamic laws as Lewin understood them. The formation and discharge of quasi-needs, the creation of systems of tension in the psychological field – these are the interpretive constructs that make it possible to obtain empirical evidence in Lewinian studies, which are structurally constructed both as observation, and as demonstration studies, and as true experiments (recall Zeigarnik).
Lewin introduced into psychology the conception of conditional-genetic laws. He held that psychological regularities extending beyond the domain of the psychology of sensation (memory, thinking, emotions) are described rather by «semi-regularities», that is, with a considerable share of deviations from the normal course. To this Lewin opposed «another faith in the lawfulness of the psychical» – based on the substantive development of psychological knowledge. He contrasts the psychology of «wholes» with the bygone era of the «psychology of elements».
According to Lewin, the essence of a law should be correlated not with the notion of a multitude (of cases), but with the notion of a type. That is, for scientific description a single case suffices, if it is a representative of a type, since the type reflects causal connections in the situation (causal-genetic properties).
On the basis of the substantive development of the theory, it is possible to distinguish dynamic factors that act with the same causality in different situations, that is, a law can conditionally-genetically explain processes that are outwardly heterogeneous (but which constitute a single type).
Conversely, outwardly similar processes may differ substantially in the structure of their causal determination. One must recognize the actual «wholes». A law reflects the causal-genetic type of a process. The decisive factors are «dynamic factors in the narrow sense of the word».
The components of a psychological law:
1) a general assertion connected with the understanding of law as the essence of phenomena and their cause-and-effect genesis;
2) the conception, special to this theory, of wholes and dynamic forces standing behind causality.
In the subsequent development of psychological methods and the methodology of science, it became clear that it is not laws but statistical hypotheses that are subjected to probabilistic evaluation.
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