Congruence Bias

Congruence bias is the tendency to test a favored hypothesis by seeking evidence directly consistent with it, rather than by designing tests capable of ruling out plausible alternative hypotheses, so that a belief is treated as confirmed once compatible evidence accumulates even though that evidence could equally be compatible with a different explanation. It is generally described as a specific case of the broader confirmation bias, applied particularly to the deliberate testing or experimentation stage of reasoning rather than only to the selective recall or interpretation of existing evidence. The psychologist Peter Wason's classic 2-4-6 rule-discovery experiments, in which participants proposed number sequences intended to test a hypothesized rule but rarely proposed sequences designed to falsify it, are commonly cited as an early demonstration of the pattern.