Bias Flashcards
what is the forensic scientist there not to prove
guilt or innocence
they are there to aid the understanding of the court
where may bias be introduced into CAI
forensics is context dependent but information if conveyed incorrectly can bias opinions
unless assessment and interpretation choices are made correctly they may introduce bias
what is meant by partiality
being bias
what is meant by impartiality
being fair and unbiased
what are the 4 things the codes of practice say a forensic scientist should act with
(relating to bias)
honesty
integrity
objectivity
impartiality
what are the two overall forms of bias seen
cognitive bias and unconscious bias
what is meant by expectation/experimenters bias
- expectation/experimenters bias = the expectation of what an individual will find what they actually found
what is meant by anchoring bias
- anchoring bias or focalism = when someone relies too heavily on a piece of information and bases everything else round that
when does bias generally occur
when the individual has too much confidence and fails to consider other suggestions
what is meant by availability heuristic
people who overestimate the importance of information available to them
what is meant by the Bandwagon effect
the probability of one person adopting an opinion based on the number of people who hold that belief
what is meant by blind spot bias
failing to recognise your own cognitive bias
what is meant by choice supportive bias
when one chooses something they tend to feel positive about
what is meant by a clustering illusion
the tendency to see patterns in random events
what is meant by confirmation bias
only listening to information that confirms our preconceptions
what is meant by conservatism bias
people favour prior evidence over new evidence or info
what is meant by information bias
seeking more information when it isn’t always relevant
what is meant by the Ostrich effect
the decision to ignore a dangerous or negative info by burying your head in the sand
what is meant by outcome bias
judging a decision based on the outcome not the making of the decision
what is meant by selective perception
allows expectations to influence how we perceive events
what is meant by survivorship bias
an error coming from focussing on surviving examples leading to misjudgement of a situation
what does the duty of the expert witness include
giving an opinion that is objective, unbiased and within their area of expertise
what does the duty of the expert witness override
any obligation to the person who the expert received instructions from or who they are paid by
what is the overall role of the expert witness
to evaluate scientific findings and the results of analytical tests in the context of the relevant case circumstances
giving an opinion that is balances, robust, logical and transparent
what is meant by contextual bias
someone has other information aside from that being considered influencing the outcome
what is meant by role effects
where a scientist identifies themselves as part of the prosecution or the defence which can introduce subconscious bias
what is meant by motivational bias
when an opinion is formed relating to a subject that has a lower level of scrutiny than one that is a less favoured outcome
what is meant by reconstructive effects
occurs when people rely on memory rather than contemporaneous notes, they fill in gaps with what they believe should have happened
when are the risks of bias lower (5)
- when the result is clear and unambiguous
- when a methodological approach is used with defined standards and quality
- using principles that have been tested and validated
- the work is thoroughly reviewed by someone who is competent and separate from the original scientist
- experience
when are the risks of bias greater (4)
- when the results is complex, of poor quality and there is an increased reliance on a subjective opinion
- when the method is unresearched
- when it is personal to the practitioner or they are less experiences
- peer review is less vigorous
what is meant by debias
reduction or elimination of impacts of bias
what is meant by photogrammetry
practice of obtaining reliable information about objects through processing of recording and interpreting photos
what is meant by psychological contamination
exposure to other info that is irrelevant to the assessment but introduces subconscious bias
what things may result in bias occurring in expert witness reports (3)
not having your work peer reviewed well by someone external
time pressures
pressure from the person who hired you
why might some people say case context is bad
they could argue it introduces bias but it is needed for CAI and developing the forensic strategy - there is a fine line not too much info needs to be given
how is the susceptibility of cognitive bias different person to person managed
this varies massively between individuals
awareness, training and competence assessments of individuals needs to be ensured
it is formally assessed prior to casework and then on a regular basis
how is the susceptibility of cognitive bias different person to person assessed (2 ways)
- through proficiency testing programmes - mock casework examples are used
- blind trails are a good way also and tend to be more reliable
these can be time consuming but exhibit good practice by the lab
what does bias link heavily with
quality
how can reconstructive effects be avoided
taking contemporaneous notes well at all stages of the investigation
it is the duty of the expert to record, retain and reveal their work
recording all info received and their interpretations
how can role effects be avoided
try to not let the person who hired you affect your decisions and remain impartial to both propositions at hand
how can cognitive bias be avoided when interpreting findings
think of all possible outcomes and then assess which is most likely using the LR
once a report is written what is recommended for good practice
verification by a second expert that is not associated with the case previously and has no info on it
the repeat the interpretation
at crime scenes what are the 4 most important things
but what is the overriding priority
scene preservation
securing evidence
speed of response
use of resources relating to crime seriousness
preservation of life
where may bias be present at crime scenes (5)
failure to secure evidence
focussing too early of false leads that can mislead investigations and how you look at a scene
gathering info before you have even got to the scene
placing cordons because it is convenient (lamp post in the right place making tape easy to put there)
using past cases you have been to to make links that don’t exist
what are the cognitive processes when getting to a crime scene (3)
setting cordons
entry and exit points
receiving information on what’s happened so far
what cognitive processes are associated with making a record of the scene (3)
equipment selection
what images to capture
sketch’s to be drawn
what type of communication if preferred to prevent introducing bias
what is the issue with this
written rather than oral as the decisions made are more transparent and clear
it is slow
what are the rules surrounding disclosure in court
the defendant does not have to disclose the strategy but the prosecution does
if there is no suitable option for objective evaluation of evidence what is used
a subjective based approach that is validated and has demonstrated robustness of conclusions and opinions previously
what is an example of a commonly accepted subjective based evaluation approach used in the UK
give an example where this may be used
ACE-V
analysis, comparison, evaluation, verification (by other examiners)
fingerprint or handwriting comparisons
where might contextual bias come into fingerprint analysis (7)
- nature and crime details
- personal knowledge w victim
- previous criminal activity of suspect
- crime location
- public interest with the crime
- personal morals
- time pressures
where might conformation bias come into fingerprint analysis (3)
- having prior knowledge of another analysts findings
- matching features that aren’t actually matches
- wanting to find a match to solve the case
give two case examples where cognitive bias was an issue in forensic science
Brandon Mayfield in 2006
Shirley McKie 1999
do reference samples introduce bias, if so why
what approach is used to prevent this bias affecting the initial analysis of the evidence
yes they can
we can start making links that weren’t made before just to say we have a match
use linear sequential unmasking
what is linear sequential unmasking
scientist must first begin with the evidence before being exposed to or working on any reference material
but they can go back to the original sample after being exposed to the reference but all changes they make must be documented
what is expected frequency bias
being accustomed to a particular result occurring at a certain rate and then expecting this rate to continue
give three ways to mitigate bias in forensic investigation
remove irrelevant context info
minimise the bias in the expected outcomes
look at reference samples after initial examination of evidence
