Motivating Factors and Bias in the Collection of Forensic Evidence Flashcards
What is forensic evidence?
Forensic evidence is information collected from a crime scene which can be analysed and presented as evidence in a court of law.
What are three strengths of using fingerprints as forensic evidence?
- Cost and time effective
- No two people ever been found with the same fingerprint - unique
- National and international databases which store fingerprints - makes analysis much easier
Outline one real life error in fingerprint analysis.
- Bombing in Madrid
- Found fingerprint on bag which had bombs in
- Matched it to the wrong person (Brandon Mayfield) as he was a person of interest from the 9/11 bombings
What did Dror suggest errors in fingerprint analysis were due to?
Due to human error or cognitive bias - people look for evidence to confirm their own personal beliefs.
What is bottom-up processing?
Examination of ridge patterns and characteristics. ‘Zooming in’
What it top-down processing?
Using contextual elements such as prior experience/knowledge, emotional state and general expectations.
What is observer/expectancy effects?
The expert anticipates the outcome as a result of information from another.
What is the conformity effect?
When you’re asked to validate the opinion of a peer, you’re more likely to agree with them.
What is need-determination perception? What is a real life example of this?
A bias due to a strong desire to solve a crime (e.g. Madrid Case)
What is overconfidence bias?
Might think they’re always right, the more experience and intelligent the easier it is to defend belief.
What is selective attention?
Prior expectations can lead to ‘filtering out’ ambiguous elements in a potential print.
What method can be used to prevent cognitive biases?
Have blind analysis - the expert knows nothing about the case and can therefore not be biased.
Outline the sample and experiment Dror used in his research into fingerprints.
- 5 volunteers
- Asked by colleague as part of normal day whether they thought a latent print matched a print from a suspect
- It was a pair of prints they had personally identified as a match 5 years earlier
- Given expectations by the experimenter that they were not a match
What did Dror find from his research?
- Only 1 of the 5 volunteers said the prints were a definite match
- 3 said definite non-match
- 1 said there was insufficient evidence
What are the main conclusions from Dror’s study of fingerprints?
That fingerprint experts can be affected by contextual information they have been given, and therefore there is empirical evidence that cognitive bias exists.
