The collection and processing of forensic evidence (biological)

Question 1

What is the type of evidence that should be collected from a crime scene?

Answer 1

• DNA
• hair sample
• fingerprints
• footprints
• dental records
• blood samples
• trace evidence
• weapon
• victim / body

Question 2

What is the key piece of forensic evidence for this topic?

Answer 2

fingerprints

Question 3

What is fingerprint analysis?

Answer 3

human beings analysing the ridges and furrows that make up a fingerprint (unique to each person)

Question 4

What is the downside to fingerprint analysis?

Answer 4

not free from human error and subjectivity

Question 5

What is the system that is used to analyse fingerprints?

Answer 5

ACE-V

Question 6

What does ACE-V stand for?

Answer 6

Analyse
Compare
Experts
Verify

Question 7

How long have fingerprints been used?

Answer 7

over 100 years

Question 8

What does the length of time that fingerprints have been used for suggest about the method?

Answer 8

very reliable and effective

Question 9

What is a key piece of evidence that goes against the use of fingerprint analysis?

Answer 9

the Brandon mayfield case

Question 10

What is the Brandon mayfield case?

Answer 10

a man falsely accused of a series of bombings in Madrid - due to multiple people (including his own lawyer) falsely identifying a fingerprint match

Question 11

How often are fingerprints misidentified?

Answer 11

2% of the time

Question 12

Who is the key background researcher?

Answer 12

Dror

Question 13

What does Dror suggest?

Answer 13

that fingerprints are too subjective and due to human examiners (human error)

Question 14

What is confirmation bias?

Answer 14

intentionally looking for evidence that would validate their current beliefs

Question 15

What are bottom-up processes?

Answer 15

purely data driven - more objective
- examination of ridges
- examination of patterns
- ‘zooming in’ - uniquely identifiable features

Question 16

What are top-down processes?

Answer 16

contextual factors that influence whether a match is made or not (more subjective)
- experiences
- expectations
- pre-conceived ideas

Question 17

How many cognitive biases are there?

Answer 17

5

Question 18

What are the 5 cognitive biases?

Answer 18

1. observer or expectancy bias
2. selective attention
3. conformity effect
4. need-determination perception
5. overconfidence bias

Question 19

what is observer or expectancy bias?

Answer 19

when the expert anticipates the outcome of the match as a result of information from another observer, therefore has as pre-conceived idea of whether a print is a match or not

Question 20

What is selective attention?

Answer 20

focusing on the ridge details so that they can match rather than ones they cannot match due to expectations

Question 21

What is conformity effect?

Answer 21

if an expert is asked to validate a match that has already been made by another expert, this may lead them to agree, unconsciously, with the original decision, especially if with a peer or superior

Question 22

What is need-determination perception?

Answer 22

when there is a strong desire or urgency to solve a crime such as serial killers

Question 23

What is overconfidence bias?

Answer 23

having more experience experts will be more confident and are more likely to believe they are right

Question 24

What was Dror’s 2006 background research?

Answer 24

• five volunteer fingerprint experts - unfamiliar with the Mayfield case
• treated as a normal working day
• prints used = definite matches from 5 years earlier in their own careers
• context manipulated & given expectations that it would NOT be a match

Question 25

What were the results of Dror’s 2006 background research?

Answer 25

• only one participant (20% / 1/5 ) agreed with original decision (a definite match)
• 80% of participants contradicted original decision
• 60% of participants completely contradicted original decision - declaring definite non-match

Question 26

What were the conclusions of Dror’s 2006 background research?

Answer 26

• failure of fingerprint experts to give reliable decisions
• affected by contextual information
• confirmation bias

Question 27

What was Dror’s 2005 background research?

Answer 27

• subliminal priming (unconsciously taking in messages)
• 27 uni students
• good quality or incomplete (poor) quality fingerprints to study - reflected real life cases (ecological validity)
• subliminal messages = ‘guilty’ or ‘same’ during initial analysis

Question 28

What were the results of Dror’s 2005 background research?

Answer 28

• control condition = 47%
• low emotional context = 49%
• high emotional context = 58%
• high emotional context (+ subliminal priming) = 66%

Question 29

What did Dror’s 2005 background research conclude?

Answer 29

where the match of the prints was ambiguous the decisions of the student participants were swayed by emotional context (top-down)