Criminal Psychology - Topic 2: Forensic Evidence

Question 1

Background Research - Dror

What is it?
What emotional states?

Reliability?
Conclusion?

Answer 1

Studied emotional motivation in finger print analysis using 27 university student volunteers in a lab experiment

He invoked two emotional states:

- Low – descriptions of minor crimes with pictures of stolen items 
- High – descriptions of violent crimes with shocking pictures (e.g. knife wound to victims face). 

• Subliminal

To further increase the strength of our top-down bias to find a match we included subliminal messages (‘guilty’ and ‘same’ messages flashed up before the fingerprints)

• All participants completed all conditions on a PC

Result:

• 66% ambiguous in the high emotional context with subliminal message whereas only 49% ambiguous in the low emotional context

Conclusions:

• When prints are ambiguous, emotional context can influence the likelihood of matching of fingerprints.

Question 2

Key Research - Hall & Player (Aim, Method, Sample, Procedure, Results)

Answer 2

Aim:

• investigated if the introduction of an emotional context affects finger print analysis and decision making.

Method:

• They used a lab experiment

Sample:

• 70 volunteers who were fingerprint experts from the metropolitan police. They were split into 2 groups

Procedure:

• one group looked at a low emotional context, a fraud case and a high emotional context, a murder case.
• The murder case had a higher emotional context due to the severity of the crime and the expert may feel under more pressure to find a match as they want to catch the killer.
• They had to test the fingerprints and report whether they found a match, how much case information they used, whether the case information affected them and would they take their findings to court.

Results:

• A lot more experts of the high emotional context felt affected by the information is the case compared to a much lower amount of the low emotional context felt affected.
• there was no significant difference in how confident the high and low emotional context were in presenting the findings to court.

Question 3

Applications (2)

Answer 3

Cognitive Training

• By training forensic examiners to acknowledge and minimise bias.
• Awareness of bias is an important step in dealing with it, but it cannot be turned off and on by willpower or awareness alone.
• Training by cognitive experts could make an important contribution in helping practitioners minimise the influence of cognitive bias on their decisions.
• For example, forensic science education could include training in basic psychology that is relevant to forensic work, such as the aspects of perception, judgement and decision making.

6 pack method

• The six pack technique - Providing one known print and one unknown print can create an expectation bias and could also lead to confirmation bias.
• By having the suspects print mixed in with 5 other known prints this
  reduces any expectation bias that the suspect print will be a match with the unknown print.