Two experiments were conducted to replicate and extend previous findings wh
ich indicated that judgment bias about the extent of one's own knowledge ca
n be decreased by a de-biasing technique called counterfactual reasoning, t
hat is, having people consider why their answers to questions may be wrong.
The results of the two experiments confirm the effectiveness of this techn
ique to decrease bias, by statistically controlling for important variables
. The results extend previous findings about its effectiveness, by showing
that counterfactual reasoning (a) reduced bias on knowledge questions about
a specific subject area and (b) reduced bias on both hard and easy test qu
estions. In addition, the two experiments establish that bias and test perf
ormance are inversely related, and a theoretical connection between this re
lationship and the ubiquitous hard/easy effect in bias research is offered.
The results are discussed in terms of decision-making processes and the po
tentially detrimental effects of bias on test performance and learning in g
eneral.