KHA312 Lecture Notes - Lecture 2: Photo Manipulation, Blind Experiment, Demand Characteristics
Psychology and Law week 2:
Lineup:
- Framing of question
- When the stakes are high this is even worse
Forensic investigations:
- Reconstruct past events:
oSomething, a crime or activity of interest
oPolice investigators are trying to work out who and what happened
Noble goal
oPhysical evidence:
Hair and fibre
DNA, Blood sample
oWitness (victim) evidence:
Mostly rely on this
Physical evidence not always available
This is where investigators typically start
- Descriptions of the offender and then later identifying them
oOften have no choice but to rely on this evidence
oRegardless of this, is it reliable
oWhen and when isn’t it reliable
How can we identify this
- Implausible and impractical saying that EW is totally reliable or totally
unreliable
- Social pressures influence
- Triers of fact rely on EW evidence
- Is EW evidence reliable:
oMistakes are not uncommon
oTypes of errors:
Incorrect ID
Picking someone who wasn’t the right person
Misses:
The bad guy is in there but witness fails to pick them
from a lineup
Might not be confident enough to pick them
Or they may have no memory
Not as much research on this
Took a long time to convince that EW were unreliable some of
the time
Criminal justice system
oEither they recognize and they pick the right one
with total certainty
oOr they don’t recognize and therefore the
suspect cannot be guilty
oLineup should consist of:
One suspect
Foils: known to be innocent
In there to prevent pure guessing
find more resources at oneclass.com
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- Consequences vary greatly
oIf incorrectly identifies an innocent suspect, trouble
Major ramifications
Increases suspicion of suspect
Can then effect forensic investigation
Might mean they are encouraged to plea guilty rather than fight
it
oID a foil that is okay
Credibility of the witness is questioned
This might influence future investigations
oMisses:
Decreases the police confidence in the suspect’s guilt
When it comes up in court that there was no ID, the prosecution
case is jeapodised
Delay the application of justice
- Evidence from lab:
oDNA
oField
oDNA exonerations
Critical to research
Most of the people that have been involved in substantial
changes, acknowledge that we would’ve got no where without
the cases of exonerations
- Example cases:
oLuis Diaz: 41 years old
Convicted of 7 charges of rape
Multiple people ID him
Details of the case:
Descriptions of Luis were remarkably consistent
Man around 190cm tall, weighed about 100kg, spoke
English but had Latin accent, swore a lot
Every description included these
Luiz: 160cm tall, weighed a lot less, spoke no English
Also ID him from lineup
DNA evidence came up 26 years later and was exonerated
- Belief in eyewitness ID vs. common sense
oSitting back objectively from the evidence it appears obvious there is
concern
oLack of critical appraisal trumps common sense much of the time
oImportant we come up with ways to eliminate this
- What is the function of the lineup:
oSee if witness can recognize the suspect from a group
oGather evidence from a witness’ evidence
oDifferent to just picking the suspect
oWe only want the suspect to be picked if they are guilty
This is often overlooked
oDescriptions provide recall information
find more resources at oneclass.com
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This leads to suspect
Often the main source of identifying suspects
oLineup provides information from recognition memory
Does ID information increase or decrease probability that
suspect is offender
oWells and Luus:
Lineup is like an experiment
Designed to test a hypothesis
Running an experiment to test this hypothesis
Suspect and foils
Instructions etc.
Test and then re-evaluate the hypothesis
Proper testing requires assessing EW memory
Like relying on construct validity
Depends on the quality of the experiment
- Simplified look at the role of memory:
oTesting memory and hypothesis
oFrom a strong memory a match is likely to be identified
oBut if not there, unlike to ID an innocent suspect
I know what I’m looking for
oThis is a strong memory
Decrease the risk of errors
oWeak memory
Not accurate, not confident
Errors are more likely
More likely to fail ID, miss, reluctant to pick anybody
Also more likely to pick someone who isn’t the bad guy
Expecting him to be there
Don’t have strong memory to rule out bad matches
oKey point:
Quality of the memory is crucial
Strong memories: reliable
Weak memory: decrease reliability and detail of the evidence
- Variables influencing EW decisions:
oDecisions based on memory vs. decision based on other cues
oMemory is fallible:
Need to consider factors that affect memory quality
Need to identify these
Cannot automatically discount EW evidence
oHow do we know what these are
Through controlled, scientific research
Methodology: current methods
Eyewitness identification studies typically involve:
oSimulated live or video crime
oEvent systematically manipulated
Eg. Exposed time of offender, presence
of weapon, race of offender
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
When the stakes are high this is even worse. Reconstruct past events: something, a crime or activity of interest, police investigators are trying to work out who and what happened. Dna, blood sample: witness (victim) evidence: Descriptions of the offender and then later identifying them: often have no choice but to rely on this evidence, regardless of this, is it reliable, when and when isn"t it reliable. Implausible and impractical saying that ew is totally reliable or totally unreliable. Triers of fact rely on ew evidence. Is ew evidence reliable: mistakes are not uncommon, types of errors: Picking someone who wasn"t the right person. The bad guy is in there but witness fails to pick them from a lineup. Might not be confident enough to pick them. Took a long time to convince that ew were unreliable some of the time.
