Two experiments with 268 paid volunteers investigated the possibility that assessment of confidence is biased by attempts to justify one's chosen answer. These attempts include selectively focusing on evidence supporting the chosen answer and disregarding evidence contradicting it. Exp I presented Ss with 2-alternative questions and required them to list reasons for and against each of the alternatives prior to choosing an answer and assessing the probability of its being correct. This procedure produced a marked improvement in the appropriateness of confidence judgments. Exp II simplified the manipulation by asking Ss first to choose an answer and then to list (a) 1 reason supporting that choice, (b) 1 reason contradicting it, or (c) 1 reason supporting and 1 reason contradicting. Only the listing of contradicting reasons improved the appropriateness of confidence. Correlational analyses of the data of Exp I strongly suggested that the confidence depends on the amount and strength of the evidence supporting the answer chosen. (21 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)