Area 2 - forensic Flashcards
what is Area 2
motivating factors and bias in the collection and processing of evidence
what are we interested in as part of collection of evidence
the validity and reliability of fingerprint analysis
what area is this under
biological- fingerprints
what is a patent fingerprint
visible to the naked eye- often made in blood, ink, paint- doesn’t take much technical collection
what is a latent fingerprint
not visible so requires use of specialist fingerprint powder, chemical reagents or light sources transferred onto surface through bodies natural oils and sweat
what is bottom-up processing
data driven from environment- what you see is what you get
sensation input-senses (eyes)
perception- processing (brain)
e.g goal keepers needing to react in situation, not predict
what is top down processing
what you expect to see- what enters your eyes is translated by cognition prior to experience
e.g. miss reading an exam question because you predict what the question is
how is bottom up processing done when analysing fingerprints
look at specific ridges (curves in fingerprint) that you can literally see - objective- more on patent print
how is top down processing used when analysing fingerprints
contextual information- prior knowlege to analyse to make predictions- more subjective- latent fingerprint
what is the case of Brandon Mayfield
US citizen who had recently converted to Muslim was accused of bombing Madrid train in 2004- after 9/11
latent finger print taken form bag of bomb- multiple experts analysed
fingerprint also matched to Ouhane Daoud
Mayfield had not left US according to passport but was still accused and jailed- FBI wanted answers
what did Kassin suggest
that forensic evidence is infallible proved by the Mayfield case and many others
what did Hampikian find
called it the ‘genetics of innocence’- found that several types of forensic science testimony had been found to have convicted innocent individuals:
e.g. 38% incorrect blood analysis
what is one of the strongest motivation factors
sense of reward experts feel when competing their part of investigation leading to case being solved.
who research the motivating factor of emotional context
Charlton- investigated presence of emotions in fingerprint examination would influence analysis
Dror- associated emotional content with crime fingerprints are from
what was the method and sample of Charlton
semi-structured interview where 13 experienced fingerprint experts asked questions like how they feel about succeeding in matching prints of murderer of 12 year old girl
what did Charlton find
5 main themes associated with emotion- reward of job satisfaction- pride, satisfaction of catching them, emotional needs for closure, satisfaction of working with long running cases, emotions linked to making mistakes and finding matches.
what did he conclude
fingerprint experts are not only emotionally motivated to achieve results for themselves, police/ wider society but also physiological factors that may lead to erroneous conclusions depending if motivation is strong enough
what was the method/ sample of Dror
experimental method, 27 volunteers from university were assigned to IV’S of high/low emotional context (experienced?) operationalised by type of crime burglary/murder - photos and stories where used to reinforce context
what was the procedure of Dror
had to match 48 ambiguous prints ( top down) and 48 non-ambiguous (bottom up)- description and photos of crime given prior - then pressed same of different for each pair
what were the findings of Dror
non-ambiguous (patent/bottom up) prints were unaffected by emotional context, ambiguous pairs were influenced by emotional context (top down /latent)- can we trust it wasn’t just their lack of experience?
who investigated the motivating factor of cognitive closure
Kruglanski - need for definite closure
what did Kruglanski say police did
looked to make firm identification so their part was complete
what did Kruglanski find
when the need for cognitive closure is high, quicker judgements are made with more confidence, however when need is low a large number of possibilities are made and better decision making occurs
what evidence did he have that would support this
Brandon Mayfield- high profile case that killed hundreds of innocent people- needed to look like they are sorting it and finding someone so made quick judgement it was Brandon Mayfield due to him recently converting to Muslim even though he hadn’t left the US according to passport and matched fingerprints with another guy.
what did Kruglanski conclude
high profile cases their is a strong need for cognitive closure and contextual information about case would lead to confident yet faulty fingerprint analysis
what did Kahneman
humans are not nearly as rational in thinking as believed, when people process information they make systematic and unintentional errors in judgement known as cognitive bias
what is a contextual bias
information about event can influence fingerprint analysis - if they have knowledge about individual this becomes focus on the individual not the fingerprint.
what is confirmational bias
looks for evidence to support pre-existing beliefs - fingerprint analysis needs to be verified and verifier may have prior knowledge that can expose experts to bias
what is the background of Hall and Player
Dror- wanted to see if certain crimes emotional context influences fingerprint experts not university students
what is the sample of Pt 1 of H+P
70 self-selected fingerprint experts from New Scotland Yark (London Police Met) average of 11 years but no less than 3 months and some no longer fingerprint experts
method of P1 H+P
Field exp- in their natural environment
IV1- low emotional context-forgery
IV2- high emotional context- murder
DV1- print match/unmatched/ insufficient etc.
DV2- whether they read crime report prior
DV3-whether they felt it affected their analysis AND would they be confident in court
Procedure of H+P
given envelope of right forefinger and asked to match on standardised 10 print form
post experiment questions- demographic information about experience/if they have presented information in court before / had it influenced their decision making?
what are the findings of H+P
57/70 read report prior- 30 form high emotion
and half of them said they felt affected
only 6% in low emotion
what’s meant by the strategy ACE-V
analysis, comparison, evaluation, verification
explain each stage of ACE-V
analysis- observe ridge patterns under microscope assessing causes of distortion and affect on the clarity of print
comparison- each inked print examined and compared detail
on latent print
evaluation- two prints examined side by side finding features in unknown print in known print- features determined if they are within tolerance for level of clarity that exists in image
verification- all positive options must be verified by second qualified expert - who must repeat process blind
explain how linear sequencing strategy works
should work in linear fashion - any info about case is ‘unmasked’ as late as possible in analysis
what psychologist demonstrated this strategy works
Dror- cost-benefit analysis if data will benefit outcome of experts analysis
explain the strategy of educating and training forensic experts
explain how open to cognitive bias fingerprint analysis is
how forensic evidence isn’t always 100%
how motivating factors can provide a basis for errors in forensic evidence
HOW? leaflet to juries? part of police training? regular checks on experts?
