EWT Flashcards
Memory
Accurate eyewitness- ppl must complete three stages of memory processing
—acquisition
—storage
—retrieval
Modal model of memory— sensory, wm, ltm
sensory: capacity— 3-7 units, duration— 0.5-3 seconds, UNATTENDED— lost info
working memory: 7 +- 2 chunks, 5-15 sec- unrehearsed — lost info
ltm- infinite capacity, permanent duration, info is not lost but may become inaccesible
error&forgetting can happen at all stages— ew memory reasonably good— under proper circumstances
Variables that affect EWT
Estimator Variables
Estimator variables— not under control of justice system— used to estimate accuracy
——event characteristics, witness characteristics- gun/knife etc, testimony characteristics
—as an expert, can only use as estimate— bc peoples estimates can vary- wide margin of error- bad
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Event Characteristics— errors of acquisition
—Disguise— accurate identification is difficult if worn during witnessed event— can include on drugs/alc- alter expression
—Viewing conditions— longer duration of exposure- better, reliable distance of witness from target, illumination amount
—24% cases pf violent cases —happen between 8pm and midnight
—person descriptors best during day time 50% correct, vs night 13% correct
—longer one sees perpetrator— better the identification
Estimate Variables cont
Weapon-focus
—more difficult to identify criminal if weapon is present
—eye tracking- gun»face
—more fixations, looking longer at gun
depends on
Expectedness— threat and situation
—photoshopped same picture of people a 4 diff places— with either
—racket at tennis court > gun at tennis court
—gun at shooting range > racket at shooting range
What really drives effect is the expectedness of situation
—if u see a person with a harmless object— threatening enviro— harmless object- taking away attention
some people said not only expectedness but also novelty
Novelty
Presence of a harmless-but novel- object has same affect
—study —people steal photos
—imagine u go into a bar— greet someone— notice unidentifiable object— weird—draws attention
—each photo unidentifiable,3 photos
Witness Characteristics
Alchohol
Very common to have intoxicated witnesses
—72% of sexually assaulted university students women were intoxicated
—13% prosecuted cases have atleast 1
—73% — officers- report-1 in a month— interview
In lab— alc vs placebo —person description- when given alcvs not to drink- no different— same detail
—focuses more on pohysical and subjective details— friendly aggresive etc
In real bar— low vs high intoxicated
—ppl good at identifying when intoxicated— no diff— correct id from lineup— but worse accuracy
Witness Characteristics
Cannabis
18% witnesses under cannabis
Lab research— impairs memory to word lists
Amsterdam coffee shop study— gave people a mock crime and lineup
—found less correct info on crime, less correct person descriptors
—but no diff in correct IDs from lineup
eval point > however mix weed and ewt effects combined» greater efect of this charracteristic
Witness Characteristic
Race
Most people better at recognising people of same race as they are
-own race bias vs cross race effect
—contact hypothesis— white bball fans and black male faces
—meta analysis— weak effect 2% variance
Own Age Bias
People have difficulty discriminating between ppl of diff ages
—better at differentiating your own age range: us study uni students vs elderly
—could argue that— bc children and eldery may have impairments— weaker evidence— causes errors
Testimony characteristics
borderline between estimate and system variables
—devasting evidence— witness standing at stand— asked do you recognise the person committed crime
—get to this when police mess up etc— cant get to that point
Initial judgement/ identification is most important— should make recording — so it is captured
—should be fast= automatic— roughly 6-12 seconds
—slow= can be deliberate
depends on confidence of witness— by itself— unrelated to accuracy
Confidence, Speed and Accuracy— with other factors
—easy to manipulate
—greatly influenced by factors
System Variables
Lineup
Variables that effect eyewitness accuracy
—under control of justice system
—psych can have direct impact on changing them— all system errors can be estimator variables-if messed up , but estimator cant be system
Line up Construction
Pre-lineup factors— Retention phase
retention interval— time between crime and identification
—large quick drop, slower rate later
—depends on factors— sooner: better
—4 hrs later 20% drop, 1 week later 50% drop
—any extraneous factors— like drawing/sketch — can be problem— like when shown drawing— remember that
—familiarity effects— multiple mugshots viewing
—all can alter memory
Retention phase
Suspect description
—quite non descript— focusing on broad characteristics— gender,age, height, weight— lot of individual variability- range of error
—describing faces- later relying on these feature— no indicator of correctness— less accurate
Retrieval Phase
Designing line up
line up fairness
—look at description provided by eyewitness
how to build abetter lineup
—suspect should match description as closely as possible— all matching in some way
—nobody should stand out— eliminate features that would make anyone stand out
—should be testing lineup— bc if u test random people who didnt see the crime— they would have chosen a specific one— shldnt be this way — 16.5% shld pick each of them
Mock witness paradigm
Having unrelated people— uni students own class— witness crime, get description— collect witness from near neighbourhood— simulating everything and experiences— same age, racial roughly-as similar to witness as possible— give description and lineup- ask who
Wells 1999– tested 10 real world line ups in lab
—showed one clear witness in a similar case
—bad lineup— ppts chose suspects 40%
Identifiable features— photoshop scars, tattoo on all suspects etc
Relative Judgement Strategy theory
how are people identifying people/ faces?
Relative Judgement Stategy— face that is relatively most similar culprit chosen— comparing each face with eachother— best match out of those to your memory
Absolute Judgement Strategy—Test face is strictly compared to culprit in memory — comparing each face separately with your memory itself— say yes or no
Types of Identification features: Show up vs Line up
Show up’s— when you bring person, getting suspect once person is captured— drive by technique — do you recognise them
— suggestive— person is already in police car, handcuffs— person can just agree
—sometimes they think its good bc— can be done quick— straight in witnesses stm — no way to gauge reliability
—clothing bias
—emotion
—trust in police force knowledge— agree
—must be only one single suspect
Lineups
Simultaneous lineup— next to eachother line
Sequential lineup— one at a time
More chance of choosing wrong person
Show up vs Lineup Stats
Meta Analysis
overall accuracy: show up 69% vs lineup 51%
target present: tie 45% vs 46%
target absent: show ups 15% vs lineups 43%
Strong reasons against show ups
—well constructed line up halves chance of innocent person being picked- 7 vs 15%
—good if administered— within reasonably short time frame— subjective, cant really determine
—angry/ tired witness might want to just pick someone— not geniune memory
