School of Psychology Professor Richard Kemp Cognitive Bias: Psychology and Forensic Science
Professor Bryan Found
Cognitive Bias: Psychology and Forensic Science What is Cognitive Bias and why does it occur? Why am I so illogical? Can I avoid cognitive Bias? Can we manage Cognitive Bias Implications for Forensic Science practice
We construct the world we live in Our experience of the world comes via our sense organs The data arriving through our sense organs is incomplete and ambiguous We need to disambiguate the information we receive We form hypotheses about the world around us
Sometimes we get it wrong!
Read this 12
And this 13
All in the mind So, the world you perceive is only in your head The reality you experience is a construction a best guess interpretation of the limited, ambiguous information made available to you But there is lots of stuff you don t even see
And then there is memory Our memory is not a veridical record of an event What we remember depends on previous experience, mood, attention, motivation, emotional state, time delay, past recall, post-event information etc. etc.
We can t always remember what we saw I am going to show you a list of words Look at the words and try to memorise them
snooze silence pillow dream night tired quilt rest Write down all the words you saw on the list
Who remembered the word NIGHT? Who remembered the word DREAM? Who remembered the word SLEEP?
Cognitive Biases Systematic patterns of thinking that may lead us to reason in an illogical manner These stem directly from the way in which we construct the world we experience We need to make sense of the data presented to us, and our approach isn t always logical
A few examples (Wikipedia!) Availability heuristic: The tendency to overestimate the likelihood of events with greater "availability" in memory, which can be influenced by how recent the memories are or how unusual or emotionally charged they may be Anchoring: The tendency to rely too heavily, or "anchor", on one trait or piece of information when making decisions Backfire effect: The reaction to disconfirming evidence by strengthening one's previous beliefs. Base rate fallacy: The tendency to ignore base rate information (generic, general information) and focus on specific information (information only pertaining to a certain case). Confirmation bias: The tendency to search for, interpret, focus on and remember information in a way that confirms one's preconceptions Experimenters bias: Tendency for experimenters to believe, certify, and publish data that agree with their expectations..
A few more Framing effect: Drawing different conclusions from the same information, depending on how that information is presented Hindsight bias: The tendency to see past events as being predictable at the time those events happened Illusory correlation: Inaccurately perceiving a relationship between two unrelated events Omission bias: Tendency to judge harmful actions as worse, or less moral, than equally harmful omissions (inactions) Zero risk bias: Preference for reducing a small risk to zero over a greater reduction in a larger risk. False consensus effect: The tendency for people to overestimate the degree to which others agree with them Fundamental attribution error: The tendency for people to over-emphasize personalitybased explanations for behaviours observed in others Naive realism: The belief that we see reality as it really is objectively and without bias; that the facts are plain for all to see; that rational people will agree with us; and that those who don't are either uninformed, lazy, irrational, or biased.
Why are we so illogical? Cognitive biases are often adaptive They can be useful heuristics They provide thinking short-cuts However, where we require logical, evidence based thinking, we need to be aware that this is not our normal mode of operation
Common Cognitive Bias Fallacies I know all about Cognitive Bias, but I am an expert so am not affected I know all about Cognitive Bias, but I think about this carefully to make sure I am not affected I know all about Cognitive Bias, but I have years of experience so am no longer affected I know all about Cognitive Bias, but I always check my results with my colleagues I know all about Cognitive Bias, but its critical that I have access to this information
Exposure to essential and extraneous information Forensic Scientists need access to some information ( Forensicicate this for me ) But how much of this information is really essential It can be difficult, but we need to control the flow of information form the investigator to the Forensic scientist If not, there is the danger of Bias and also Double counting of evidence
Double counting of evidence If a forensic science is valid then it has some value to an investigation, independent of other sources of information If a fire scene analyst can look at a scene and tell whether an accelerant was used then this is valuable But what if s/he also knows that the owner of the premises was in financial difficulty, recently increased their insurance cover, and was filmed buying cans of petrol If they use this information to influence their conclusion then the jury will effectively hear this evidence twice and it will be double counted
Cognitive Bias and Forensic Pathology You are the experts, not me I can describe the problem and explain how important it is I can offer some potential solutions and point out what wont work But only you can work out the best strategy within your profession
Controlling Cognitive Bias: Actuarial vs Clinical assessments
So what can I do? Accept: Accept this is a feature of the way we all think. Believe: Don t try to deny it or explain it away Control: Instead, introduce controls to the way you work to check and try to limit the impact of these biases Document: Describe what information you were exposed to and when, and explain why its important to know this. Describe how cognitive biases may affect your conclusions See Found, B., & Edmond, G. (2012). Reporting on the comparison and interpretation of pattern evidence: recommendations for forensic specialists. Australian journal of forensic sciences, 44(2), 193-196.
Control Manage the flow of information in your workplace Explain to investigators what you want to know and what you don t want to know Consider a Sequential unmasking approach Carefully record your opinions at each stage of the process remember these will change once you are exposed to new information and you wont remember what you thought previously Peer Review and Wisdom of crowds: Only if independent decisions
Cognitive Bias: Psychology and Forensic Science What is Cognitive Bias and why does it occur? Why am I so illogical? Can I avoid cognitive Bias? Can we manage Cognitive Bias Implications for Forensic Science practice
Cognitive Bias: Psychology and Forensic Science What is Cognitive Bias and why does it occur? : That s the way we are built! Why am I so illogical? Can I avoid cognitive Bias? Can we manage Cognitive Bias Implications for Forensic Science practice
Cognitive Bias: Psychology and Forensic Science What is Cognitive Bias and why does it occur? : That s the way we are built! Why am I so illogical? : Because biases can be useful short-cuts Can I avoid cognitive Bias? Can we manage Cognitive Bias Implications for Forensic Science practice
Cognitive Bias: Psychology and Forensic Science What is Cognitive Bias and why does it occur? : That s the way we are built! Why am I so illogical? : Because biases can be useful short-cuts Can I avoid cognitive Bias? : No, not unless you stop being human! Can we manage Cognitive Bias Implications for Forensic Science practice
Cognitive Bias: Psychology and Forensic Science What is Cognitive Bias and why does it occur? : That s the way we are built! Why am I so illogical? : Because biases can be useful short-cuts Can I avoid cognitive Bias? : No, not unless you stop being human! Can we manage Cognitive Bias : Yes with careful design of work practices Implications for Forensic Science practice
Cognitive Bias: Psychology and Forensic Science What is Cognitive Bias and why does it occur? : That s the way we are built! Why am I so illogical? : Because biases can be useful short-cuts Can I avoid cognitive Bias? : No, not unless you stop being human! Can we manage Cognitive Bias : Yes with careful design of work practices Implications for Forensic Science practice : This is up to you but don t ignore it
Essential reading Useful reading Found, B., & Edmond, G. (2012). Reporting on the comparison and interpretation of pattern evidence: recommendations for forensic specialists. Australian journal of forensic sciences, 44(2), 193-196. Edmond, G., Martire, K., Kemp, R., Hamer, D., Hibbert, B., Ligertwood, A.,... & Thompson, M. (2014). How to crossexamine forensic scientists: a guide for lawyers. Aust. Bar Rev, 39, 174-196. Edmond, G., Found, B., Martire, K., Ballantyne, K., Hamer, D., Searston, R.,... & Tangen, J. (2016). Model forensic science. Australian Journal of Forensic Sciences, 48(5), 496-537.
Questions? Contact: Professor Richard Kemp School of Psychology University of New South Wales Sydney 2052 Australia Email: Richard.kemp@unsw.edu.au Phone: 0415430668