Comparing Mediation Inferences and Explaining Away Inferences on Three Variable Causal Structures

AbstractPeople reliably make two errors when making inferences about three-variable causal structures: they violate what is known as the Markov assumption (mediation) on causal chains and common cause structures, and fail to sufficiently 'explain away' on common effect structures. Our goal for the present study was to quantitatively compare these two errors after subjects have learned the statistical relations between three variables using procedures designed to maximize the accuracy of their learning and inferences. Aligning with prior research, we found that subjects violated the Markov assumption, and did not sufficiently explain away. We also found judgments about mediation were worse than judgments about explaining away for one inference, but better for another, suggesting that people are not uniquely worse at reasoning about one structure than another. We discuss the results in terms of a theory of cue consistency.

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