Causal paradox: When a cause simultaneously produces and prevents an effect

Explored a basic claim of causal model theory which postulates that the interpretation of the learning input is directed by prior causal assumptions. An example of this is Simpson's paradox which describes the fact that a given contingency between two events which holds in a given population can disappear or be reversed in all subpopulations when the population is partitioned in certain ways. 84 college students participated in two studies examining their assessment of a contingency between a potential cause and an effect. The task in Experiment 1 (36 subjects) assessed the strength of causal relation between the irradiation of tropical fruit and the quality of the fruit. The organization of the list reflected a variant of Simpson's paradox in order to assess whether subjects' contingency judgments reflected their prior assumptions about the additional grouping variables. Experiment 2 (48 subjects) replicated the results of Experiment 1 with a grouping variable that was kept constant across the two conditions. Subjects assessed the causal efficacy of a new watering technique applied to two types of plants. It was shown that subjects' assessment between a cause and an effect is moderated by their background assumptions about the causal relevance of additional variables and the mode of presentation of the learning items. Subjects' assumptions of the relevance of an additional grouping variable led to the view that the cause enables the effect or the view that it deterred the effect. It is concluded that the acquisition of new causal knowledge is based on old causal knowledge which is already accessible at the beginning of the induction process.

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