Cognitive Bias In Forensics Flashcards
Expectation/Experimental Bias
Also known as experimenter’s bias, where the expectation of what an individual will find affects what is actually found
Confirmation Bias
Closely related to expectation bias, whereby people test hypotheses by looking for confirming evidence rather than for potentially conflicting evidence
Anchoring or Focalising
Closely related to both of the above and occur when an individual relies too heavily on an initial piece of information when making subsequent judgements, which are then interpreted on the basis of anchor.
Contextual Bias
Where someone has other information aside from that being considered, which influences the outcome of their consideration
Role Effect Bias
Where scientists identify themselves within adversarial judicial systems as part of either the prosecution or defence teams
May introduce subconscious bias that can influence decisions, especially where some ambiguity exists
Motivational Bias
Motivational influence on decision making results in information consistent with a favoured conclusion tending to be subject to a lower level of scrutiny than information that may support a less favoured outcome
Reconstructive Bias
Reconstructive effects can occur when people rely on memory rather than taking contemporaneous notes
In this case people tend subsequently to fill in gaps with what they believe should have happened, and so may be influenced by protocol requirements when recalling events some time later from memory
Confirmation Bias
Confirmation bias is closely related to expectation bias, whereby people test hypotheses by looking for confirming evidence rather than for potentially conflicting evidence
Bias Countermeasures
Blinding Precautions are the most powerful means of safeguarding against the introduction of contextual bias.
This is by ensuring the practitioner conducting analysis only has information about the case relevant to their analysis.
Limitations: without relevant information, the case assessment, targeting and interpretation may be hampered down.
Madrid Bombing 2004 Case Study
Case showing the effects of expectation bias.
Brandon Mayfield was an Oregon attorney, arrested by the FBI and held as a material witness
His arrest was based on a misidentified partial fingerprint found at the scene in Madrid
FBI fingerprint examiner’s conclusions were confirmed by at least two additional FBI examiners as well as a defence examiner
Two weeks later, Spanish National Police matched the fingerprint to an algerian Ouhnane Daoud, and mayfield was released
ACE-V
comparison method for fingerprinting to work around bias
Analysis
Comparison
Evaluation
Verification
Forensic Expert Role
The role of a forensic science expert is to evaluate scientific findings and the results of analytical tests in the context of the relevant case circumstances
Expert Opinion Criteria
Balanced
- Considered alternate propositions
- Both defence and prosecution views should be considered
Robust
- Based on data relevant to the proposition being considered and that are available for inspection and discussion
Logical
- In the approach taken to evaluation
Transparent
- Another suitably qualified scientist could follow the steps and decisions taken
