Congruence bias is the tendency of individuals to focus on testing their initial hypothesis while ignoring alternative possibilities. This cognitive error leads individuals to perform tests that confirm their original beliefs rather than seeking evidence that might disprove them, which reflects a broader category of confirmation bias. In essence, people feel more comfortable repeating tests that align with their assumptions instead of considering different avenues of inquiry that could challenge their views.
A classic example of congruence bias was demonstrated by Peter Wason, where participants were given the sequence '2, 4, 6' and asked to identify the rule governing it. Most people assumed the rule was 'numbers ascending by 2' and only tested sequences that confirmed this assumption, ultimately failing to discover that the actual rule was simply 'list ascending numbers.'
To avoid congruence bias, actively seek alternative hypotheses and design tests that can potentially disprove your initial assumption. Consider questions like 'What would I expect to see if my hypothesis were false?'