Biased evaluation of incriminating and exonerating (non)evidence

Recent evidence suggests that convictions in criminal procedures are susceptible to biased decision making. In this study, the potential detrimental effects of confirmation bias and the feature positive effect (FPE) were explored. The former states that decision-makers will be more impressed by incriminating than by exonerating evidence. The latter states that they assign more weight to finding evidence than to the failure to secure it, even though the absence of evidence can be as diagnostic as its presence. Law students read a case file about a fistfight. The evidence was manipulated such that the effect of confirmation bias and FPE on guilt estimation and conviction rate could be assessed. Findings partly confirmed the presence of both a confirmation bias and an FPE.