Intentionalismintentionality Psychological Theory Of


INTERACTION AND MAIN/TREATMENT EFFECTS. The interaction effect is a pattern of data in statistics obtained from mul-tifactorial analysis of variance in which the influence/effect of a manipulated [or independent variable (IV)] factor varies across different levels of another IV, or across combinations of levels of other IVs or factors. Under such conditions, variation in the measured [or dependent variable (DV)] factor is not the result of a simple additive combination of the IVs/factors; for example, the IV of "task difficulty" and the DV of measured "arousal level" often interact whereby increased "arousal" increases performance on "easy tasks," but decreases it on "difficult tasks;" cf., Yerkes-Dodson law). The principal difficulty with interaction effects, once discovered in data, is that they are very difficult to interpret, and where a graphing of the levels and factors on an "interaction graph" is somewhat helpful. In contrast to an interaction effect, the concept of a main effect/treatment effect refers to a statistically significant difference between two or more means/averages; a two-way interaction is a statistically significant difference between two or more differences between means/aver-ages; and a three-way interaction is a statistically significant difference between two or more differences between two or more differences between means/averages, and so on; however, the data interpretations beyond three-way interactions are extremely complex both in understanding and in graphing results. In graphing interaction effects, say for a two-way interaction, the vertical axis represents scores on the DV, and the horizontal axis represents different levels of one IV, and each line on the graph denotes a different level of another IV; if the lines so constructed are parallel, it signifies that there is no interaction effect present, but if the lines cross or are nonparallel, it signifies that there is an interaction effect present, at which time the data may be tested further for statistical significance using specialized "post-hoc" statistical procedures or tests. See also AROUSAL THEORY; YERKES-DODSON LAW. REFERENCE

Ray, W. J. (2003). Methods toward a science of behavior and experience. 7th ed. Belmont, CA: Wadsworth/Thomson.

Brain Blaster

Brain Blaster

Have you ever been envious of people who seem to have no end of clever ideas, who are able to think quickly in any situation, or who seem to have flawless memories? Could it be that they're just born smarter or quicker than the rest of us? Or are there some secrets that they might know that we don't?

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