The CSI Effect VS. Cognitive Bias in Forensic Science
Written by Amanda Tabert
Crime drama series are an increasingly popular genre on modern television (VanArendonk, 2019). If you have ever surfed through channels for something to watch, then you may have heard of shows such as “Criminal Minds”, “Law and Order: Special Victims Unit”, or “CSI: Crime Scene Investigation”. In these shows, the investigators use their high-tech methods to analyse crime scene evidence with near-perfect accuracy, which usually allow them to spend no more than one episode to solve crimes and put criminals behind bars.
It sounds legitimate and is certainly entertaining to the fan-base, but this perception of the investigation process is generally referred to as the “CSI Effect” by those who work in real-life forensic sciences. One of the CSI-produced misconceptions is how evidence is analysed in forensic labs. DNA evidence is considered the most concrete piece of evidence in the courtroom because “DNA don’t lie”. Unfortunately, this process is not quite as simple as it seems – the evidence may not lie, but that doesn’t mean forensic examiners are bullet-proof to human errors. To explain this, let’s take a look at what researchers have been digging into…
In one experiment, forensic anthropologists were tasked to simply identify the sex of a female skeleton. To make things interesting, the researchers told some examiners what the sex was before they started – that is, some examiners were told that the skeleton was female while others were told it was male (Nakhaeizadeh, Dror, & Morgan, 2014).
Now, we know that a biological male’s pelvic bone should be narrow and steep, while a biological female’s pelvis is comparatively larger to accommodate childbirth. If we know this, then experts should be pros at this. Right? Well, not all the time, because the researchers found that 100% of the examiners who were told that the sex was female correctly identified it as female. Great, but! Out of those who were falsely told that the sex was male, only 14% made accurate sex assessment of the female skeleton.
How did this happen? How could 72% of the expert examiners be influenced into making an incorrect judgement just based on the information they were given prior to their assessment? Here’s what the research indicates: strong contextual information can “contaminate” the judgement of even the most experienced forensic examiner. This psychological phenomenon is a form of what is called “cognitive bias.”
Perhaps you’re still skeptical about how easily our minds can be influenced, so let’s take a look at another example of cognitive bias in forensic fingerprint analysis.
Researchers tasked a group of fingerprint experts to identify some fingerprints taken from a real-life crime scene. The same group of experts were invited back five years later to examine finger prints. Except the researchers switched things up in this second round of examination. Unbeknownst to the experts, not only were they examining the exact same set of fingerprints they did five years previously, but this time they were also given misleading information that the prints would not match the suspect in question (Dror, Charlton & Péron, 2006). And here is what the researchers found: most of the fingerprint experts changed their verdict in line with the context they were given and contradicted their own initial assessment.
What are we to make of all this? That forensic science is pseudoscience? Not at all. In fact, the issue isn’t with the forensic experts themselves, but the examination procedures. If the examiners are simply given the evidence (and nothing else) to analyse, it can greatly eliminate the bias resulting from being cognitively contaminated with contextual information (Dror, Thompson, Meissner, Kornfield, Krane, Saks, & Risinger, 2015).
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Reference
Dror, I. E., Charlton, D., & Péron, A. E. (2006). Contextual information renders experts vulnerable to making erroneous
identifications. Forensic Science International, 156(1), 74-78. https://doi.org/10.1016/j.forsciint.2005.10.017
Dror, I. E., Thompson, W. C., Meissner, C. A., Kornfield, I., Krane, D., Saks, M., & Risinger, M. (2015). Letter to the Editor-
Context Management Toolbox: A Linear Sequential Unmasking (LSU) Approach for Minimizing Cognitive Bias in
Forensic Decision Making. Journal of Forensic Sciences, 60(4), 1111-1112. https://doi.org/10.1111/1556-4029.12805
Nakhaeizadeh, S., Dror, I. E., & Morgan, R. M. (2014). Cognitive bias in forensic anthropology: Visual assessment of
skeletal remains is susceptible to confirmation bias. Science & Justice, 54(3), 208-214.
https://doi.org/10.1016/j.scijus.2013.11.003
VanArendonk, K. (2019, Jan 25). Why Is TV So Addicted to Crime? Vulture. Retrieved from
https://www.vulture.com/2019/01/why-is-tv-addicted-to-crime-shows.htm
Disclaimer
The blog posts are for informational and educational purposes only. The posts should not be considered as any type of advice (medical, mental health, legal, and/or religious advice). All blog posts have been researched, written, and edited by the undergraduate students and alumni of the Lifespan Cognition Lab. As a teaching and research-based lab, we encourage all lab members to help make knowledge more accessible to all communities through these posts.
