If you judge, investigate! Responsibility reduces confirmatory information processing in legal experts.

Fair and well justified judicial decisions require that judges evaluate and interpret all relevant facts. However, heuristics and other shortcuts are used here as well. Additionally, it has been demonstrated that experts may be subject to the same decision biases as laypeople. Therefore, we investigated whether and to what extent judicial experts are protected against confirmatory information processing (CIP), a tendency to seek out (selective exposure) and evaluate information more positively (biased assimilation) when it confirms one's own preliminary decision. Results indicate that legal experts (judges, prosecutors, and defense-lawyers) evaluated information supporting their preliminary decision more positively than conflicting information. However, there is a clear expertise effect: domain-specific experts (e.g., criminal-law experts deciding a criminal-law case) showed less CIP than general experts (legal professionals with specializations in other fields than criminal-law), who did not differ from laypeople (pilot study). We further investigated whether either decision-certainty, knowledge, or a feeling of responsibility can be identified as potential underlying mechanism of this expertise effect. Higher decision-certainty or prior knowledge did not correlate with CIP (pilot study). In our main study, general experts significantly reduced their CIP to the same level as domain-specific experts if we induced responsibility. Without this induction general experts again showed more CIP than domain-specific experts. This implies a motivational explanation for the lower CIP in domain-specific experts. The advantage of specialized judges over general judges will be discussed.