Cognitive fallacies and criminal investigations.

The human mind is susceptible to inherent fallacies that often hamper fully rational action. Many such misconceptions have an evolutionary background and are thus difficult to avert. Deficits in the reliability of eye-witnesses are well known to legal professionals; however, less attention has been paid to such effects in crime investigators. In order to obtain an "inside view" on the role of cognitive misconceptions in criminalistic work, a list of fallacies from the literature was adapted to criminalistic settings. The statements on this list were rated by highly experienced crime scene investigators according to the assumed likelihood of these errors to appear and their severity of effect. Among others, selective perception, expectation and confirmation bias, anchoring/"pars per toto" errors and "onus probandi"--shifting the burden of proof from the investigator to the suspect--were frequently considered to negatively affect criminal investigations. As a consequence, the following measures are proposed: alerting investigating officers in their training to cognitive fallacies and promoting the exchange of experiences in peer circles of investigators on a regular basis. Furthermore, the improvement of the organizational error culture and the establishment of a failure analysis system in order to identify and alleviate error prone processes are suggested.