New cognitive bias affecting evaluation processes: Generosity-erosion effect

Researchers of the University of Barcelona, together with researchers from the University of Zurich (Switzerland) and Brown University (United States), have analysed more than 10,000 evaluations that were carried out to candidates who wish to hold a public teaching permanent in Catalonia. The objective was to study how the decision by the committee of evaluators is affected by the fact that each candidate holds a certain position in the lists of people to be assessed. The study, published in the journal Science Advances, identifies a new cognitive bias that researchers have named "generosity-erosion effect". It involves that once the evaluators have scored one candidate generously, they tend to act harsher to the subsequent ones.

Researchers considered the fact of giving someone a score of 5.00 -the minimum grade to pass- a generous gesture, since it allows people to pass the exam when they would be on the verge of failing it. In addition, it is hard for evaluators to assess the merit of a candidate at a decimal level. Once this parameter is set, the study shows that the likelihood of success decreases by 7.7% for each previous candidate that received the lowest accepted score to continue with the hiring process.

Authors provide some explanations for this generosity-erosion effect. One could be guilt-aversion: evaluators would tend to be generous and overgrade candidates who are on the verge of failing in order to avoid the feeling of guilt, but once they have given a score of 5 to some candidates this feeling of guilt is reduced and they are likely to act harsher on others. "We observed the mechanism that affects the final score is not fatigue nor the contrast with the previous candidate or the expectations of the examination board, as stated in other studies: it is mainly guilt or the generosity-erosion effect", notes Jordi J. Teixidó, researcher of the Faculty of Economics and Business of the UB and co-author of the article.

The study, also signed by the UB researcher Tania Fernández, Marc Lluís Vives (Brown University, United States) and Miquel Serra-Burriel (University of Zurich, Switzerland), uses tools from the social science game theory to interpret the results of the analysis. The selection process to hire teachers showed proper features for the study, since those candidates to be assessed were listed randomly without a certain order, and the decision was not taken individually but by a committee, which is becoming more common in selection processes.

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