Topic 2 - The collection and processing of forensic evidence

Question 1

Key Research

Answer 1

Hall + Player (2008) - Will the introduction of an emotional context affect fingerpring analysis + decision making.

Question 2

Aims

Answer 2

To investigate whether the crime report of a crime would affect experts’ analysis of a poor quality print.

To establish whether fingerprint experts would be emotionally affected by the circumstances of the case.

Question 3

Sample

Answer 3

70 volunteer fingerprint experts
Worked for the MET Police Fingerprint Bureau
Experience ranged from 3 months to 30 years
Half were assigned to a low emotion case (forgery) the other half assigned to a high emotion case (murder)

Question 4

Procedure

Answer 4

A fingerprint was scanned and superimposed onto a £50 note.

Each participant was given a £50 with the note on, the 10 fingerprints of the suspect, crime scene examiners report.

The study was conducted within the experts’ typical day, ie. they had no time limit.

They had access to a magnifying glass + a Russell Comparitor.

P’s were also asked to complete a survey regarding their demographic info, whether they thought it was a match or not and whether they had referred to the crime scene report or not

Question 5

Findings

Answer 5

57/70 read the crime scene report
52% of people in the high emotion crime presummed that this had affected their decision
6% in the low emotion thought this affected their decision

No significant difference was found between the two groups in the judgement of their fingerprints

Question 6

Conclusion

Answer 6

Emotional context did not affect the ability of fingerprint experts to make a decision when analysing fingerprints.

Question 7

Dror - Top Down Biases

Answer 7

Top-down approaches use the experts previous knowledge to make an assumption about the identity of the fingerprint.

Cognitve Biases -

Expectancy Bias = Analysists are affected by their previous expecatation of the outcome

Selective Attention = Ignoring differences in fingerprints, excessively focusing on similarities.

Conformity Effect = Fingerprint analysist may conform to the outcome suggested by supervisiors / detetive prime suspects.

Need-Determination Perception = Rushed into inaccurate analysis as they are eager to close the case

Overconfidence bias = Fingerprint analysists believe that their judgement will always be right

Question 8

Dror (2005) - Research

Answer 8

27 University students given 96 pairs of fingerprints to compare and identify matches.

Half were easy matches / half hard matches

Either low emotion (theft) or high emotion (murder) - images were shown to reinforce this.

Sometimes the subliminal message of ‘guilty’ would pop up with the prints.

High emotional cases were more likely to find a match (58%) than low emotion (49%)

Subliminal message = 66% matches

Emotional context influences fingerprint analysis

Question 9

Linear Sequential Unmasking (LSU)

Answer 9

1. Analyse the crime print alone - without a comparaison print - and record key details
2. Analyse the comparison print // reveal information about the crime.
3. The expert can then revisit their notes, however they cannot edit their previous notes.
4. They then stated how confident they were of a match

Question 10

Miller

Answer 10

Six-Pack Idea

Miller suggests that forensic experts should be given 6 pieces of evidence, to prevent them focusing on one.

This overcomes the experts’ susceptability to need-determination bias.

This makes experts more careful when making matches

Question 11

Application - Reduce possible bias within experts

Answer 11

1. Use 6 pieces of evidence - Miller
2. Limit crime info - LSU
3. Improve bias awareness - Dror