Human Factors in Forensic Science: Psychological Causes of Bias and Error

Forensic science evidence has long been accepted in court and is widely considered infallible. However, the forensic sciences have recently come under intense scrutiny, as forensic science errors have been implicated in an alarming number of wrongful convictions. In working to better understand and prevent such errors, researchers have discovered that they are often an unfortunate byproduct of innate psychological processes. In this chapter, we first review evidence that forensic science examiners, like all humans, are vulnerable to unconscious biases that can lead to erroneous judgments. Second, we identify barriers to mitigating the pernicious effects of bias in forensic laboratories and courtrooms, including widespread misconceptions about its causes and effects. Third, we discuss proposed reforms to strengthen forensic science, and we describe some progress that has already been made in that regard.