Do Observer Effects Matter? A Comment on Langenburg, Bochet, and Ford

Abstract

ABSTRACTWe identify methodological problems in Langenburg et al. (2014), which undermine its conclusions about the size of the observer effect problem and the importance of sequential unmasking as a solution. The scoring method of Langenburg et al. (2014) appears to be subjective. The classification of cases is not congruent with the three keys to observer effects in forensic science: the analyst's state of expectation, the analyst's state of desire, and the degree of ambiguity in the evidence being examined. Nor does the paper adequately support its claim, “[I]t has been asserted that the high context/high interaction cases are essentially where there is the most danger of bias.” While the paper tends to minimize concern over observer effects, the evidence in it seems to support the view that fingerprint analysts look to contextual information to help them make decisions.