Crime topic 2 = The collection and processing of forensic evidence (biological)

Question 1

Key research

Answer 1

Hall and Player - if introduction of an emotional context affect finger print analysis and decision making

Question 2

Aims of Hall and Player

Answer 2

To see whether a written report of crime could affect the fingerprint identification of a poor quality print by experts
And whether the level of emotion in written report affects identification of poor quality prints

Question 3

Sample of Hall and Player

Answer 3

70 volunteers working for the Met Police in London

Question 4

Sample method by Hall and PLayer

Answer 4

Self selected sample as 70 fingerprint experts from Met Police responded to a request and volunteered to the study

Question 5

Apparatus of Hall and Player

Answer 5

14 copies of a £50 note with a superimposed obscured finger print
Crime scene examiners report
Context of crime
10 print form of possible suspects

Question 6

How did Hall and Player create a scenario to test fingerprint experts?

Answer 6

Make up a fake crime with fake reports, evidence, suspects etc
Either given a high emotional or low emotional context of crime
Asked participants to deduce suspect from fingerprint

Question 7

Why were 14 prints made in Hall and Players study

Answer 7

To check for consistency that same results occur no matter the print

Question 8

How did we know the print on £50 note was obscured in Hall and Players study

Answer 8

Other fingerprint experts confirmed the results were ambiguous so could therefore be open to bias

Question 9

Hall and Player procedure: what were participants given?

Answer 9

Give every participant a crime scene report, £50 note with obscure print, suspect print form and written up context of crime (manipulated IV to either be high or low emotional context)

Question 10

Independent variable of Hall and Player

Answer 10

The crime was high emotional context or low emotional context as written in the crime scene report given to participants

Question 11

High emotional context of crime in h+P

Answer 11

Allegation of murder that suspect shot victim

Question 12

Low emotional context of crime in H+P

Answer 12

Allegation of forgery by paying for goods with forged 50 pound note
NO VICTIM

Question 13

Experimental design of H+P

Answer 13

Independent measures, half the participants (35) were given high emotional context crime and other half low emotional context then compared

Question 14

What type of research is H+P?

Answer 14

Experiment because there is an IV

Question 15

What type of experiment is H+P?

Question 16

After participants in H+P were given the crime scene report etc…..

Answer 16

Asked to complete identification of fingerprint to suspect as if it were part of normal working day
Use a magnifying glass for fingerprints and comparator
Then report what they found

Question 17

Why was H+P high ecological validity?

Answer 17

Because they completed study as if it were normal working day so could leave whenever they wanted and had no time limit
So accurate to normal working environment = naturalistic behaviour

Question 18

How did H+P have participants report their identification of suspects?

Answer 18

By self report in a questionnaire

Question 19

H+P questionnaire at end of the study

Answer 19

Demographic questions on who the P is + how many years they worked
Whether they thought a match could be made or not, or if not enough detail was available and justifications + observations of the identification process

Question 20

How many participants in Hall and player had read the crime scene report?

Answer 20

57/70
So 13 didnt know the emotional context

Question 21

H+P results: how much did participants believe the emotional context affected results?

Answer 21

52% in high emotional context believed the report of the crime biased/ affected decision, significantly higher than 6% in low emotional context condition

Question 22

In hall and player, was a significant difference found in actual identification of suspect between participants in high/low emotional context ?

Answer 22

No, their judgment was not affected even though Ps in high emotional context thought it had

Question 23

Conclusions of H+P

Answer 23

The emotional context of a crime did not affect ability of fingerprint experts to find identification

Question 24

Additional research

Answer 24

Dror - top down biases
Dror - research with 27 students
LSU (Linear sequential unmasking)
Miller - 6 pack idea

Question 25

Dror research - what are the 2 processes used in fingerprint matching?

Answer 25

Bottom up Top down

Question 26

Bottom up approaches in fingerprint matches

Answer 26

Data driven analysis of ridges and patterns to identify unique match (more objective)

Question 27

Top down approaches in fingerprint matches

Answer 27

When the expert's previous experience and knowledge is used to make AN ASSUMPTION about the identity of the fingerprints if the ridges are unclear and objective analysis cant be done

Question 28

Problem Dror found with top down processes

Answer 28

Less objective identification + more open to mistakes: Expert's biases and expectation will falsely influence analysis

Question 29

2 biases that decrease objectivity of top down process

Answer 29

Conformity effect Observer bias

Question 30

Observer bias problem in top down process of fingerprint analysis

Answer 30

The expert will anticipate if there is a match or not based on previous knowledge of crime learnt from police so may interpret the data based on this expectation So not accurate identification

Question 31

Conformity effect problem in top down process of fingerprint analysis

Answer 31

If fingerprint expert is asked to confirm the identification of a fingerprint done by peers/superiors, they may be more biased to agree with their finding

Question 32

Dror's research on students sample

Answer 32

27 students

Question 33

Dror's research on students IV

Answer 33

Whether the fingerprint pair was part of a low (burglary) or high emotional context (murder) Whether subliminal messages flashed on screen

Question 34

Procedure of Drors research on 27 students

Answer 34

Show 96 pairs of fingerprints, half clear match, half more ambiguous Show images of context of each crime before Participant presses button if they think it matches or not

Question 35

How did Dror manipulate the IV?

Answer 35

Either the fingerprint pair was from a crime with a high emotional context or low emotional one Reinforced by flashing images on screen before each pair of what the crime scene looked like Subliminal messages appearing saying guilty

Question 36

DV of Dror

Answer 36

Number of matches participants made in high emotional contexts or low emotional contexts

Question 37

Results of Dror

Answer 37

Participants were shown high emotional cases they were more likely to find a match between fingerprints (58%) compared to the low emotional cases (49%) When the subliminal messages were added to the emotional cases, this rose to (66%)

Question 38

Conclusions of Dror

Answer 38

Emotional context of a crime given in info before identification will affect analysis In students, not necessarily true for experts

Question 39

Circular approach in identification of finger prints

Answer 39

Analyst is given suspects print and evidence print from crime scene and looks between them to find identification in ridges etc Changes can be made on whether there is a match or not etc

Question 40

What is wrong with the circular approach in identification?

Answer 40

Bias because expert may only look for specific ridges that match and can be influenced = CONFIRMATION BIAS of looking for specific details to confirm experts expectation

Question 41

How to overcome bias in circular approach in identification?

Answer 41

Use Linear sequential Unmasking (LSU)

Question 42

Linear sequencing unmasking step 1

Answer 42

Look at the print from the crime scene on its own and make notes on unique details and features Decide if enough detail is present for possible identification

Question 43

Linear sequential unmasking step 2

Answer 43

Give small amounts of information about the case little by little in order of importance to identify if the info is consistent #CANNOT GO BACK AND CHANGE NOTES SO THIS NEW INFO DOES NOT BIAS NOTES MADE BEFORE

Question 44

What piece of evidence did Miller consider in his theory?

Answer 44

Hair strands not fingerprints

Question 45

What type of bias did Miller say was present in police analysis?

Answer 45

Need determination bias

Question 46

What is need determination bias?

Answer 46

When experts felt they had to find a match on crime scene hair to suspect hair so they claimed to find a match when not true to reality

Question 47

Miller's six pack idea

Answer 47

Expert given 6 strands of hair to compare against crime scene hair 1 is from suspect and other 5 is fillers so expert doesnt know which is suspect's hair Will be more careful than just blindly finding a match

Question 48

applications for reducing bias in processing and collection of forensic evidence : 6 Pack idea

Answer 48

Use 5 filler samples and 1 from suspect when comparing to crime scene one - not know which sample is from suspect or filler - eliminate need confirmation bias - need to be more careful and objective in analysis - Miller's six pack idea

Question 49

applications for reducing bias in processing and collection of forensic evidence : Awareness of top down biases

Answer 49

Educate themselves on conformity effect + Observer bias - apply more bottom up approach of data driven analysis for unique details - Dror found inaccurate identifications were made as a result of top down processes where experts are influenced by biases and expectations fro what theyll find

Question 50

Applications for reducing bias in processing and collection of forensic evidence: limit amount of information learnt of context

Answer 50

Only allow experts to view information relevant to comparison between prints - In lead up to analysis, avoid presenting info on nature of crime and victim etc - Dror found matches were more likely if participants saw high emotional context compared to low one