Topic 2 Criminal psychology Flashcards
What is the summary of Hall and Player?
Hall and Player investigated whether introducing an emotional context would affect the decisions made by expert fingerprint analysts about whether a fingerprint from a suspect matched that from a crime scene. Their sample was made up of 70 volunteer fingerprint experts from the Metropolitan Police who had a mean length of experience of 11 years. Participants were given a £50 note with a fingerprint on it and were asked to identify if the print matched a comparison set of fingerprints. They analysed the fingerprint as part of their normal working day at the Fingerprint Bureau, and had access to a magnifying glass and a Russell Comparator. Half of the participants were given a crime scene report saying the print had come from someone suspected of forgery (low emotional context). The other half were given a crime scene report saying the print had come from someone suspected of murder (high emotional context). There was no significant difference in the number of fingerprint experts finding a match between a suspect’s fingerprint and a fingerprint from the crime scene in an emotionally upsetting case than in a case that is less emotional.
What is Dror about?
Top down biases
Top down: use the experts previous experience and knowledge to make an assumption about the identity of the fingerprints.
Bottom-up: use of examination of the ridges and patterns of the fingerprint to identify the features of each fingerprint to see if they match.
Examples of top down biases:
-expentancy bias: preconceived expectations about the outcome.
-selective attention: filtering out ambiguous elements
-Conformancy effect: knowledge of og decision unconsciously biases the analyst to agree with it.
Need-determinism perception: error occurs due to a strong need to get evidence.
Overconfidence bias: expert has so much confidence in their work that they believe they are always right.
What is Linear Sequential Unmasking (LSU)?
Analyse the crime scene print-on its own while looking for and recording any unique features and deciding if there’s enough detail to make a comparison
2.Later, extra info will then be given in order of importance to the case to help make a comparison
Expert can then revisit and add to his/her analysis but cannot delete or make changes to initial interpretations. They can also say how confident they are saying its a match or not.
What is Dror et al about?
-Given 96 pairs of fingerprint to compare to its pair
fingerprints were related to low/high emotional crimes/
Subliminal messages including words ‘same’ or ‘guilty’ were flashed on computer screen.
ppts in high emotional cases were more likely to find a math between fingerprints (58%) compared to the low emotional cases (49%)
Rose to (66%) when subliminal messages were flashed
suggests that an emotional context influences fingerprint analysis.
BUT IT WAS CONDUCTED WITH NON EXPERTS
What is Miller about?
Miller looked t their sample analysis and found that hair experts were susceptible to need determination bias when matching a hair at a crime scene to a suspect’s hair saying the evidence matches to get a result.
Instead of giving experts 1 hair from the crime scene and 1 hair from the suspect to compare to 4 fake hairs and 1 actual hair from the suspect (the 6 pack)
One group used the 1v1 method and the other used the 6 pack method. The group who used the ‘6 pack’ made less false positives when matching pairs.
What are the applications of topic 2 criminal psychology?
A police forensic evidence analyst could use the LSU to reduce selective attention bias. for example, an analyst could look at evidence on its own and record any unique features and decide if there is enough to compare. Then they can get extra information if needed in order of importance to the case. They can revisit and add to analyse but not remove anything. This would reduce selective attention because the analyst cannot ambiguous elements to get a match.
Forensic evidence analysis could use the six pack to reduce expectancy bias . For example, an analyst could get one piece of evidence from the crime scene, four pieces of fake evidence and one piece of evidence from the suspect and have the experts compare. This would work because Miller showed that the group of students made less positives, using the six pack, therefore this would reduce expectancy bias because you have to compare five prints compared to just one so your preconceived thoughts about the suspect are gone.
A police forensic evidence analyst could use not having information to reduce needed determination bias for example an analyst could not get given crime scene report in high emotional cases until after their decision was made . This would work as 52%of participants in the emotional context in H&P believe reading the report influence their decision and therefore not having information reduces need determination bias as you don’t have a strong desire to find evidence.
