A preliminary investigation into the influence of case information and surface material effects on the judgments of forensic science undergraduate students within the discipline of bloodstain pattern analysis

There is growing concern about human bias and limitations in forensic science practice. The United States National Academy of Sciences has specifically highlighted that forensic sciences “rely on human interpretation of what could be tainted by error” [1]. An array of literature has shown that particular domains of forensic science, such as fingerprint interpretation are vulnerable to bias and error. Less attention has been paid to the bias in evaluation of bloodstain pattern analysis. In the current study, a sample of 32 forensic science undergraduates from the United Kingdom were asked to report the number and type of bloodstains present on six different surfaces. The surfaces were systematically varied in terms of colour and porosity. Further, participants were provided with ‘case information’ to investigate if details about the source of the bloodstains would bias a re-appraisal of the bloodstains. We found that the participants found the dark, non-porous surfaces particularly challenging when identifying the number of bloodstains present on a surface. The accuracy at detecting the specific types of bloodstain varied more as a function of the individual participant than the surface material. From this study, it was found that case information had no effect on the reappraisal of the bloodstains. The results highlight the importance of utilising varied resources in the education of novices in bloodstain pattern analysis. Therefore, these findings will be of interest to all those involved in bloodstain pattern analysis training and education.