Crime topic 2 Flashcards
(15 cards)
Why are fingerprints used?
Easy to collect and analyse, no 2 people have the same fingerprint, can be digitally stored.
What 2 inconsistencies did Dror (2011) identify?
Inter-observer consistency- difference between fingerprint examiners
Intra-observer consistency- difference in one fingerprint examiner over time
What are the 4 motivating factors with forensic evidence processing?
Conformity effect, need-determination perception, overconfidence bias, expectancy bias
What did Dror (2015) suggest?
Top-down approach- experts previous experience and knowledge makes assumptions about identities.
Bottom-up approach- examination of ridges and patterns to identify unique features
What did the expectancy bias study Dror (2006) imply?
5 fingerprint experts studied for 12 months, unfamiliar with the Mayfield case. Asked to examine a pair of fingerprints, they had actually seen the fingerprints 5 years earlier on a real case recorded as a definite match. In this study the ps were told they were wrongly identified and there was no match. 4/5 changed their decision
What did the emotional context study Dror (2005) suggest?
27 uni students (non-experts) were given 96 fingerprints, 48 clear, 48 ambiguous. Some crimes were low context (bicycle theft, burglary), high emotion (murder or assault). Photos were used to reinforce the crime. Ps had to click a button same or different to match. Ps with HEC found a match of 58% vs LEC 49%.
What was Hall and Players aim?
To investigate if a written report would emotionally influence the fingerprint experts and if emotional context would bias the judgement of fingerprint experts.
Who were the ps?
70 volunteer fingerprint experts from the Metropolitan Police Fingerprint Bureau, experience of 2 months to 20 years.
What materials were used?
Fingeprint of individuals right forefinger inked onto paper, scanned onto a £50 note, it was not clear.
Brief summary of procedure?
It was part of their normal working day, given access to a magnifying glass and a Russel comparator. They were supplied with a routine crime scene examiners report. No time limit, but could not discuss study with others. LEC group- forged £50 note, HEC group- suspected of firing two gunshots into a victim and leaving.
Ps had state whether it matched, did not match, didn’t have enough detail or some agreement. A final questionnaire was given out on how and why they came to their decision and if they read the crime scene report.
What were the main results?
57/70 read the report
52% of 30 ps HEC said it affected their decision vs 6% in LEC, suggesting there is a relationship to a certain extent.
Not much difference with final decision made.
What were the conclusions?
Emotional context does not reduce the ability to make a final decision.
Some experts did not read the report- it is not necessary.
Section A question?
- Aim, Sample, RM and procedure
- 52% who read HEC felt it affected their decision vs 6% in the LEC, indicating a perceived effect on decision making. Less experienced analysts should avoid reading crime scene report, so it doesn’t bias fingerprint identification.
- Some experts did not read the report and felt confident that it was not necessary to establish a match. Role of training is important, members of the MET police are well trained, may not be true of every police department, training should be emphasised.
- There was still a perceived influence on the report. Need-determination may have occurred as experts have a strong desire to solve the crime and see justice done.
Section B plans?
Individual- Hall and Player, context did not affect decision making BUT 52% of ps in the HEC felt it affected decision making.
Situational- Dror (2006) study, BUT 4/5 changed it is an individual decision.
Both- Dror (2005) students predisposed to solve the crime, affected by need determination bias, but situation needs to be activated.
Determinism- Dror (2005) emotional context influenced decision BUT hard to decide if it would affect real life fingerprint analysis.
Determinism 2- Dror (2006) expectancy bias caused experts to not find matches BUT experts did not have the choice to identify the prints.
Free will- Hall and Player- experts are able to remain impartial, which suggests an element of free will BUT the cause of experts not being affected by need determination perception is actually their years of training and experience.
Reductionism- Cognitive biases are reductionist BUT many are based on social factors eg conformity
Holism- Hall and Players, complex process BUT it could be a simplistic reason of being trained to ignore cognitive biases.
Both- Dror (2005), affected by emotion but also more complex, than just emotion.
Scientific criteria-
Cause and effect- Hall and Player manipulated the IV of high or low emotional context to test the likelihood of experts finding a match or mismatch BUT were allowed to take a break so controls may not have been kept.
Objective data- Hall and Player but also asked questions which is subjective.
Controls - Dror et al (2006) high controls, eg all ps unfamiliar about the Mayfield case BUT some were uncontrolled, experts did this as part of their work.
Useful criteria-
Practical applications- Hall and Player, implications for the justice system, defends validity and reliability of fingerprint analysis BUT Dror et al (2005) is less practically useful as it merely shows that students will be slightly biased by HEC
ecological validity, internal validity, ethnocentrism
Socially sensitive criteria-
Stigma- Dror et al (2006)- stigmatise occupation of forensic scientist as being prone to bias or inaccuracy BUT stigma could be excusable because the profession is scientific and unbiased.
Controversial- Hall and Players research should not be controversial as it suggest fingerprint experts do their job accurately and without bias BUT it may be able to suggest they perceive themselves to be affected by emotional context as the public would like them to be impartial.
Political consequences- Dror et al (2006) could have negative consequences if they were used to undermine credibility in forensic science BUT if the experts are actually producing invalid responses as it is important these steps taken to improve accuracy.
Ethics-
Deception- Hall and Player did not deceive their ps as they were already fingerprint analysis so knew what would be the procedure BUT Dror et al (2006) deceived their ps as they were intentionally told their prints had been wrongly identified to activate an expectancy bias.
Informed consent- Hall and Player gained consent from their ps due to them volunteering BUT Dror et al (2006) did not gain informed consent from the fingerprint experts as this would require revealing they were taking part in an experiment.
Right to withdraw- Hall and Player ps would have been allowed to remove themselves from the research if they wished by not making a final conclusion BUT Dror et al’s (2006) experts would not be able to withdraw as they didnt know they were in there.
Section C applications?
Application 1-
Linear sequential unmasking (LSU), forensics examiners should work in linear, rather than a circular line, to prevent bias. The information should be given in order to the experts to give them an explanation, it is gradually unmasked. It helps prevent expectancy bias. The expert must examine and document the trace material from the crime scene before being exposed to the reference material such as case reports. The forensic expert should make an initial analysis of a fingerprint and only be given case information either when it is necessary or as late as possible in the examination. LSU reduces the need-determination perception- people don’t have an urge or drive to save the crime as they wont know the emotional context. Dror (2012) believed it is important to impose limits on when examiners are permitted to revisit and alter their initial analysis of trace evidence. BUT Dror (2015) suggests there are some practical issues associated , 1- it requires more effort, 2- decisions about which information to provide, 3- hard to understand which type of information will have an effect.
