Motivating Factors in Collecting and Processing of Forensic Evidence

Question 1

Why is there problems in collection and processing of forensic evidence

Answer 1

its a cognitive process
therefore open to biases and motivating factors

emotional context of crime
poor quality fingerprints so subjective interpretation

Question 2

What did charlton et al find

what was the problem with the research method (interviews)

Answer 2

fingerprint experts can be emotionally motivated to achieve results

experts gave socially desirable answers
interpretation of interviews could be subjective

Question 3

Dror et al sample + aim (lab experiment so good controls)

Answer 3

AIM - to see whether manipulating the emotional context of crime affected interpretation

SAMPLE - 27 university volunteers, mean age 23, at Sussex university UK

Question 4

Dror et al results

Answer 4

Participants were more influence by context when given unclear fingerprints

ie. if high emotional context, more motivated to match unclear fingerprints

Question 5

Dror et al
- Sampling bias
- Ethnocentrism

Answer 5

Sampling bias
- university students (not experienced)
- volunteers (more obliging)

Ethnocentrism
- cognitive biases from UK only
- western bias

Question 6

Bias in Forensic Evidence

Answer 6

Cognitive closure
- people want a conclusion to decison-making process
- Madrid bombings, 200 died so motivation to get cognitive closure

Contextual bias
- contextual details eg. background that make expert bias
- occurs when unclear fingerprints

Conformation bias
- people interpret new evidence to confirm their pre-existing beliefs

Question 7

Top down processes

Bottom up processes

Answer 7

TOP DOWN - starts with bigger picture then fills in details

BOTTUM UP - forensic evidence first, then build a theory of what happened
- reduces conformation bias

Question 8

KEY RESEARCH - HALL AND PLAYER
Aim
Sample

Answer 8

AIM - to see if emotional context of a case affects identification of fingerprints

SAMPLE - self selected sample of 70 fingerprint experts, working for metropolitan police fingerprint, UK

Question 9

KEY RESEARCH - HALL AND PLAYER
Procedure

Answer 9

The fingerprint experts asked to compare a smudged £50 note with a set of prints. Half were low emotional context condition, half were high emotional context condition

Low emotional context = fraud involving forged notes where suspect fled the premises after shop assistant said it was fake

High emotional context = same information but criminal fired two shots and killed the victim then fled

Question 10

KEY RESEARCH - HALL AND PLAYER
Findings

Answer 10

Little different in identification rates between the high and low emotional context conditions

suggests emotional context doesn’t affect identification

However, fingerprint experts were asked at end if they thought case report affected them and they thought it did

Question 11

KEY RESEARCH - HALL AND PLAYER
Sampling bias

Answer 11

Mean no. of year experience was 11 years
= well-trained so good analysis
= less likely to be affected by emotional context
= not representative of all fingerprint experts

Research conducted in UK by Metropolitan Police Fingerprint Bureau
= centred on one culture
= different views of crime between culture + different cognitive biases

Question 12

KEY RESEARCH - HALL AND PLAYER
Validity

Answer 12

LOW ECOLOGICAL VALIDITY
- participants knew it wasn’t a real fingerprint/crime
- not as affected by emotional context
- increased validity as in natural workplace doing everyday task, examining fingerprints

GOOD INTERNAL VALIDITY
- cause and effect
- extraneous variables
- however field experiment - reduced

Question 13

KEY RESEARCH - HALL AND PLAYER
Reliability

Answer 13

STANDARDISED PROCEDURE
- all participants shown same scanned fingerprint on £50 note
= position of fingerprint was standardised
= all given same post-experiment questionnaire

Question 14

Research into collection and processing of forensic evidence socially sensitive

Answer 14

Charlton -concluded experts are influenced by psychological factors
- legal implications for legal systems as forensic evidence may not be objective

Dror - participants more influence by context when given ambiguous fingerprints
- fingerprint evidence not be trusted in court

Hall & Player - suggests we can trust analysis of trained fingerprint experts

Overall- should do bottom-up processing to stop contextual bias + conformation bias

Question 15

Usefullness

Answer 15

Charlton - careful in high-profile cases so miscarriages of justice doesn’t occur

Dror - bottom up processing

Hall and Player - restore confidence in legal system

Question 16

Strategies for reducing bias in collection and processing of forensic evidence

Answer 16

> ACE-V
Linear Sequential Unmasking

Question 17

PARA FOR ACE-V

Answer 17

HOW
- Analysis = unsolved fingerprint analysed for patterns
- Comparison = known fingerprint examined to see if similar to unsolved fingerprint
- Evaluation = evaluated side by side to see if similar
- Verification = positive identification verified from second-qualified expert

WHY
- objective, standardised way of analysing fingerprints
- stops conformation bias by verification

Question 18

PARA FOR LINEAR SEQUENTIAL UNMASKING

Answer 18

HOW
First - examine evidence from the crime scene and give confidence levels in their analysis
Second - case report is read only if it helps them with identification

WHY
Dror - examiners should limited to alter their analysis as its affected by later infomation
- context of crime doesnt affect analysis
- no conformation bias