Lecture
a) Special effects.
There exist psychological regularities that are based on basic variables which are actualized only in a combination of a number of manipulated conditions, that is, they are associated with the use of factorial designs.
1) The Stroop effect, known to us from the course on memory and attention. In general terms, this effect can be characterized as difficulty in the voluntary performance of an action when conditions of incongruence between the source and the content of commands are arranged. (It has been found in various modalities. In the visual modality: a slowing of reading speed if the word «blue» is written in red letters).
2) Experimenter effects. (The personality traits of the experimenter are superimposed on the personality traits of the subject; the impact of the expectations and attitudes of the subject and the experimenter, etc.).
«Subject effects». The motivation of being evaluated.
These factors are usually considered at the stage of primary control and in assessing the representativeness of the data. Experimenter effects may serve as sources of both systematic and non-systematic confounding.
These effects must be considered in the context of the experimental material, that is, of the task factor. Four characteristics of tasks that favor the manifestation of experimenter effects: 1) the experimenter’s participation in the subject’s activity; 2) the ambiguity of the tasks; 3) the difficulty of the tasks; 4) the correspondence between the nature of the task and the experimenter property under consideration.
The study of these problems gave rise to «centaur designs», in which the task factor varies in an intra-individual sequence, while the personality property of the experimenters or subjects is controlled by selecting groups that differ in the given property.
Experimenter effects can be illustrated with the material of
Johnson’s experiment (the seductive behavior of the experimenter)
b) Factorial designs for the representation of statistical data
The tabular form of presenting results sometimes looks the same for different ways of obtaining the data. The levels of a factor (which give the names of the columns or rows in the table) do not necessarily mean that an experimental study was conducted; it could also have been a passive-observational one. It may be a statistical summary, a table analogous to a factorial design, in which, however, the given variables were NOT controlled. Example: a study of Russian adolescents, on the influence of periods of stability and instability in society on the level of trait anxiety. The study covered 4 periods. The second variable is the age of the subjects, the third is sex. Result: for the younger group the influence of instability is more evident, and differences between boys and girls were also found. That is, a number of important regularities were found which, however, cannot be discussed in the context of causal hypotheses, since the variables – analogues of the IV – were not subjected to experimental control, and the extraneous factors were not controlled. Moreover, the psychological variable proper is not isolated here: there are many contextual variables in which the influence of instability could be specified, so that the field of competing hypotheses is practically unlimited.
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