Context/background
analysis of fingerprints relies on ability of an individual to recognise, analyse and interpret friction ridges.
Emotional context impacts decision making during the examination
Usually, the latent marks are incomplete, smudged, distorted, rotated or obscured, so to secure quality, the process is conducted independently
Aim
To investigate whether fingerprint experts are emotionally affected by case details and to see if emotional context has a bias effect on the judgements of experts
Method
lab experiment, artificially generated task, p's were randomly allocated to 1 of 2 conditions
Iv= low context group (were told the crime was forgery) or high context group (were told the crime was murder)
Dv= whether the specialist read crime reports first, whether they thought the fingerprints were a match, or not, or insufficient, or sufficient to establish identity but not enough to compare, or whether they'd present the evidence in court
Procedure
All the p's were respondents to a request for volunteers to take part in an experiment (details not given)
70 fingerprint experts working for the Met Police with 3 months-30 years experience
Materials
To validate decisions, a finger impression was used from a known source
The finger was inked and put on a piece of paper
It was scanned to a computer and super imposed onto an image of a £50 note
It was positioned so the background of the note obscured the majority of the ridge details
The mark was then manipulated to control contrast and obstruct the discernible detail of the latent mark
14 copies of this park were printed for use in the experiment
All copies were compared to ensure consistency
All 10 printed fingers were given to p's who gave their opinions as to whether there was a match
Each expert had a magnifying glass and a Russel comparator (magnifying unit for comparing 2 images)
Procedure
P's randomly assigned into groups, and asked to treat the experiment as a job
They could come and go and speak together but not about the fingerprints
There was no time limit for the case
They were assigned into 1 of 2 groups, low emotional context or high emotional context
They were given an envelope containing 1 of the test marks, the relevant 10 print forms, the crime report and a sheet advising them of the contents
They were asked to decide if the mark was
1- a match
2- not a match
3- insufficient
4- sufficient in identity but not enough to compare
They were then given a feedback sheet and asked whether or not they had referred to the crime report prior to their assessment of the marks, and to say what information they remembered reading
Results
57/70 read the crime report examining the prints
52% of the 30 who had high emotional context felt affected by that information
only 6% felt affected in the low context group
This shows that the relationship between type of context and effects on experts
70% were confident enough to present their marks in low context, but 17% in high emotional context
Conclusion
Emotional context does affect experts feelings, but it doesn't influence final outcome/decisions
Individualisation = being able to isolate a suspect by determining that a print could've only come from them
Evaluation
High ecological validity
Artificial because they knew it was a study, so more controlled but less valid
Willing to participate, harm was minimal and confidentiality was secure