The Collection and Processing of Forensic Evidence

Question 1

Two types of data processing

Answer 1

1. Bottom-Up where you compare latent print with a database using the ridges.
2. Top-Down referring to the contextual effects such as emotion leading to confirmation bias

Question 2

Types of confirmation bias

Answer 2

1. Expectancy Bias- expert anticipates outcome
2. Selective Attention- Filtering out the ambiguous elements to make a match
3. Need Determination Perception- Arising when there’s a strong desire to solve a case i.e. rape.

Question 3

Dror’s Aim

Answer 3

To investigate whether an increased emotional context will lead to an increased match likelihood.

Question 4

Dror’s Sample + Procedure

Answer 4

He used uni students and asked them to match fingerprints from manipulated contexts, high or low emotion depending on image either knife or lamp.

Question 5

Dror’s Results

Answer 5

More ambiguously matched fingerprints in the high emotion condition. suggesting a need determination bias

Question 6

Dror’s Pros

Answer 6

• Useful applications
• Lab experiment
• Quantitative data

Question 7

Dror’s Cons

Answer 7

• Not using experts, can’t be generalised
• Lacks ecological validity as no consequences
• Demand Characteristics

Question 8

Hall and Player Aim

Answer 8

Investigate whether experts from MET fingerprint Bureau show a bias for matching ambiguous pairs in high emotion contexts.

Question 9

Hall and Player Sample

Answer 9

70 experts with experience ranging fro, 3 months to 30 years. Self selected

Question 10

Hall and Player Procedure

Answer 10

Latent fingerprint placed £50 note and deliberately obscured to be only just identifiable. All given same tools to help them match it. Randomly placed in high (shoots gun twice after caught with fake note) or low (runs away when caught) emotion context. DVs were if they read examiners report, their verdict and if they’d confidently present the print in court.

Question 11

Hall and Player Results

Answer 11

Very few from other condition matched the prints, 57/70 actually read the report. High emotion experts admitted to being after by the report but no links with that impacting analysis. Few confident enough to present in court.

Question 12

Hall and Player Suggests

Answer 12

Emotional Context plays a role in an experts feelings but doesn’t produce top-down processing bias. Experts better than non experts.

Question 13

Hall and player Pros

Answer 13

• Lab experiment, high control
• standardised procedure
• Quantitative data
• useful applications
• used target population

Question 14

Hall and Player cons

Answer 14

• Demand characteristics
• Lack ecological validity as no consequence
• not generalisable as self-selected

Question 15

Applications suggested by Kassin

Answer 15

• Educate the general public
• Blind Testing
• Linear analysis rather than circular
• The filler control method
• Blind to context

Question 16

Educating the public

Answer 16

Teach about the subjective nature and its vulnerabilities to bias.

Question 17

Blind Testing

Answer 17

The verifier should not know who the initial analyst was, and the analyst shouldn’t pick the verifier to remove bias risk

Question 18

Linear analysis

Answer 18

Initial analysis of latent print should be before the comparison is made to reduce bias

Question 19

The filler control method

Answer 19

Analysis given multiple prints so that theres no need determination bias and they select the most accurate.

Question 20

Blind to context

Answer 20

Awareness of context may lead to top-down processing so should be avoided to ensure perception isn’t effected