The collection and processing of forensic evidence Flashcards
What is the Brandon Mayfield Case?
On 11th March 2004 a bomb attack happened in Madrid resulting in 191 people killed and 1800 injured.
A latent finger print was created from a bag believed to have belonged to the bomber.
Identife as Brandon Mayfield.
Mayfield protested innocence. During the trial Spanish police matched the print to the real bomber, an Algerian national called Ouhnane Daoud.
Outline Dror et al (2005)
Dror believed that there are sources of human error when forensic experts are analysing evidence. Dror believed that these errors were best explained by something which he called cognitive biases
What is conformation bias?
when people observe more by intentionally look for evidence that would validate their current beliefs. They are ignore evidence that would contradict their beliefs.
What is oberver or expectancy bias?
when the expert anticipates the outcome as a result of information from and initial observer and the outcome.
Selective attention: prior expectation can lead to the ‘filtering out’ of poor
What is conformity effect?
if a fingerprint expert is asked to validate the decision of a peer, or of a superior, this effect may unconsciously bias them to agree with the original decision if they are aware of it.
What is need determination perception?
this bias arises from a strong desire to solve a particular crime
What is over confidence bias?
experts may experience overconfidence bias and this may make them believe that they are always right, even in the face of contradictory evidence. The more experienced and intelligent they are, the easier it is for them to defend their biases and beliefs.
What was the aim of research by Hall and Player (2008)
To invesigate:
The fingerprint experts were emotionally affected by the case details in the report.
Emotional context would bias the judgements of experts analysts
What research method was used?
Laboratory experiment / Naturalistic
What was the IV?
Whether the participant was allocated to the low-context or the high-context group.
What was the DV?
The way the participants analysed and interpreted the fingerprints: did they look at the report, was the fingerprint a match, was there enough detail to undertake a comparison and was the participant confident to present the fingerprint in court as evidence.
What were the materials used?
The fingerprint was placed on a £50 note.
Fourteen copies of this mark were then printed for use in the experiment.
The finger mark and the corresponding set of fingerprint
Each participant was allowed equipment normally used in the process
What was the sample used?
Volunteer sample of a group of fingerprint practitioners.
70 fingerprint experts working for the Metropolitan Police Fingerprint
What were the results?
A total of 57 of the 70 participants (81.4%) had read the crime scene examination report before examining the prints.
52% of the high context scenario felt that they were affected by the information given on the examination report compared to 6% in the low context scenario.
What are the conclusions from this research?
Emotional context does affect experts’ feelings but it does not influence the final outcome of their analysis (because no difference was observed between the high and low emotional contexts)
