factors affecting eyewitness testimony Flashcards
summarise anxiety on EWT?
- anxiety= has strong emotional and physical effects (which can be triggered by stressful events) and can negatively effect accuracy of EWT —> research shows possibilities that recall may actually be better in presence of high anxiety
what negative effect may occur due to anxiety on recall/acciracy?
Weapon focus effect (WFE)
what is weapon focus affect (negative effect of anxiety) and why is it bad?
- tends to happen during commission of crime in which a weapon is used
—> eyewitnesses may fixate on weapon due to fear/flight or fight response etc
—> due to intense focus on weapon = person wielding it isn’t really noticed (eyewitness does not take in their height, hair colour etc)= recall of details of perpetrator = virtually non-existent or recall of any other details of the event
who did research on the weapon focus effect?
Johnson and Scott 1976
research on WFE procedure and findings
- ppts told they were taking part in a lab study and asked to sit down in waiting area —> ppts split into low and high anxiety group —> while ppts waiting in waiting area:
- low anxiety grp overheard casual convo from a room and saw a man walk out with a pen and grease on his hands
- high anxiety group overheard an argument from the room and saw a man walk out with a knife and blood on his hands
—> ppts asked to identify the man from a set of 50 photos
Findings
- low anxiety group = correctly identified the man (mean accuracy 49%)
- high anxiety grp = accuracy 33%
—> concluded anxiety focuses attention on the weapon and away from other details of the event. Tunnel theory of memory= ppl have enhanced memory for central events
why may anxiety have positive effects on EWT accuracy and recall?
- may be due to an increase in hormone adrenaline which triggers fight or flight response or freeze= high state of alertness
who carried out research into positive effects of anxiety on EWT accuracy/recall?
Yuville and Catshell 1986
research into positive effects of anxiety on EWT procedure and findings?
- witnesses of a real life crime shooting (in Canada where shop owner shot a theif dead)= asked to participate (13 witnesses)
- ppts were interviewed 4-5 months post shooting —> interviews were compared to police interviews at original time of shooting
- accuracy = measured by number of matching details in each interview
- ppts asked to rate their stress levels at time of incident (7 point scale) and related issues e.g. insomnia
Findings:
- witness recall= accurate as events recalled 4-5 months later matched original police reports
- witnesses who resorted high stress at time of incidence = most accurate recall (88%)
- low stres = 75% accuracy
—> suggests anxiety doesn’t have negative effect on recall if events (accuracy, it may actually enhance it)
what is the explanation for contradictory findings
Yerkes and Dodson 1908 proposed tehres a relationship between arousal (emotional state) and performance
—> called Yerkes-Dodson law (as well as inverted U theory) + can explain contradictory findings related to accuracy of EWT
(see diagram on mind map)
explain The U theory (related to contradictory findings of EWT.
- when crime is witnessed, a person becomes emotionally (anxiety) and physiologically (adrenaline release) aroused
- low levels of arousal (anxiety) = associated with low levels of performance (recall and accuracy in EWT)
- as arousal increases performance increases up to an optimum
- after this point if arousal continues to increase = performance starts to decrease
anxiety affecting EWT eval - 1
Johnson and Scott may not have studied anxiety
—> oops may have looked at weapon because they were surprised not scared
—> Pickel 1998 did research using unusual objects (chicken, scissors etc) —> found EWT less accurate when unusual objects are involved —> suggests weapon focus effect = due to surprise rather than anxiety
ALSO
Johnson and Scott study= unethical (deception etc) + lacks ecological validity = demand characteristic etc
anxiety affecting EWT eval 2
study support idea that anxiety leads to less accurate recall
—> Valentine and Mesolithic (2009) found ppts recall of actors in London Dungeons = less accurate with high compared to low anxiety
—> study = used objective measure of heart rate to measure anxiety = high validity and supports WFE
anxiety affecting EWT eval 3
study support the idea that anxiety leads to higher accuracy of EWT
—> Christionsan and Hubriette 1993= found higher recall in witnesses of a real life bank robbery —> victims of robbery (high anxiety) had better recall of the details of tiggers compared to bystanders (low anxiety)
—> supports Yuille and Cutshall
BUT both these researches used a real life context and crime as part of investigation= invalidates findings due to lack of control over confounding variables which could influence recall and accuracy of EWT e.g. post event discussions
anxiety affecting EWT eval 4
- Yerkes Dodson law / inverted U theory= doesn’t account all factors contributing to anxiety e.g. cognition, emotion state, physical health which could affect accuracy of EWT
—> Yerkes Dodson law = too simple
anxiety affecting EWT eval 5
- most research takes a nomothetic approach = problematic as small sample which can’t generalise to everyone
