How Can Cognitive Bias Impact Forensic Evaluations? New Innocence Project Review Article Takes a Closer Look

Examiner swabbing evidence

**This is a guest post from The Innocence Project Researchers**

Can cognitive biases, which are a common feature of human decision-making, affect the outcome of forensic evidence analysis? An April 2019 review article by researchers from the Innocence Project shows that yes, even well trained and experienced forensic scientists may be susceptible to confirmation bias.

“Confirmation bias” is the tendency we all have to look for and remember information that matches our initial impressions or beliefs and to discount contradictory information. “Cognitive bias research in forensic science: A systematic review” by Glinda Cooper and Vanessa Meterko examines confirmation bias in the context of the evaluation of forensic evidence.

The review, published in Forensic Science International, encompasses 29 studies covering 14 different forensic disciplines. These studies explored, for example, whether case information irrelevant to the forensic testing influenced analysts’ conclusions. For instance, one study asked whether the type of clothes found with a skeleton could affect forensic anthropologists’ conclusions regarding the sex of the skeleton based on their analysis of the bones.

Other studies examined the process used to choose samples for comparison, like whether a crime scene hair sample is compared to hair from a single suspect or to a “line-up” of samples from several people, similar to a line-up used for eyewitness identification.

Study results indicate that laboratories can take preventative steps to avoid situations that can make analysts vulnerable to confirmation bias. Limiting access to unnecessary information, such as whether a suspect confessed, is one such strategy. Other measures include using multiple comparison samples, and blinding analysts to any previous evidence evaluation results.

One of the key recommendations of the 2009 National Academy of Sciences report, Strengthening Forensic Science in the United States: A Path Forward, was to encourage research on human observer bias and human error. Researchers have heeded this recommendation, evidenced by this review article ranking among the most downloaded articles in this journal.

CSAFE researchers are also investigating techniques to limit the impact of human factors, and distinguish between task-relevant and irrelevant information for forensic scientists. We look forward to collaborating with the forensics community as we work together to promote increased accuracy in forensic evidence analysis.

Ensuring Accurate Analysis of Biological Evidence: The NIST Human DNA Standard


DNA profiles can play an important role in criminal investigations. However, ensuring accuracy when developing genetic profiles is key.

In July 2019, NIST researchers released the latest version of a human DNA standard to help crime labs get the technique right. With this standard, labs get not only the DNA itself but also an accurate DNA profile for comparison.

DNA labs use the NIST standard to double-check their instruments and methods. The goal of using a standard is to promote quality control, prevent wrongful convictions due to faulty processes. Researchers explain that this way if questions come up in court, experts can say “We’ve properly calibrated our instruments using the NIST standard.”

NIST forensic DNA scientist Becky Steffen takes a closer look at the human DNA standard in her Q&A article.

CSAFE researchers utilize other NIST standards such as the standard bullet to calibrate our instruments and promote accuracy. Learn more about how CSAFE uses the NIST standard bullet in our firearms and ballistics analysis.

OSAC Public Update and Open Discussion Recordings Now Available


Did you miss The Organization of Scientific Area Committees for Forensic Science (OSAC)  Public Update & Open Discussion meeting? Videos and presentations are now available from the June 5, 2019 meeting held at NIST.

Featured presentations include updates from the five Chairs of the Scientific Area Committees (SAC), three Resource Committees, the Statistics Task Group, and the Forensic Science Standards Board (FSSB). Review the recording to learn about the latest activities for each OSAC unit, including new standards under development, identified research gaps, challenges being addressed, and priorities for the upcoming year. Audience questions and feedback are also available for viewing. Slides from the individual presenters can be found under the agenda section on the meeting website.

The OSAC works to strengthen the nation’s use of forensic science by facilitating the development of scientifically sound forensic science standards and by promoting the adoption of those standards by the forensic science community.