MEMORY: accuracy of eyewitness testimony - anxiety

effects of anxiety

• negative effect on accuracy - affect on memory and performance in general - complicated cognitive tasks are reduced by stress

key study Johnson and Scott 1976

weapon focus effect - the view that a weapon in a criminals hand distracts attention (because of anxiety it creates) form other features and therefore reduces the accuracy of identification

procedure

• to test this effect Johnson and Scott 1976 asked particpanst to sit in a waiting room where they heard an argument in an adjoining room and then saw a man run through the room carrying either a pen covered in grease (low anxiety condition) or a knife covered in blood (high anxiety, ‘weapon focus’ condition)

• participants were later asked to identify the man from a set of photographs

findings

• the findings supported the idea of the weapon focus effect

• mean accuracy was 49% in identifying the man in the pen condition, compared with 33% accuracy in the knife condition

• loftus et al 1987 showed that anxiety does focus attention on central features of the crime (e.g the weapon). the researchers monitored eyewitnesses eye movements and found the presence of a weapon caused the attention to be physically drawn towards the weapon itself and away form other things such as the persons face.

anxiety has a positive effect on accuracy

there is an alternative argument that says high anxiety/ arousal creates more enduring and accurate memories.

for example there is an evolutionary argument that suggests it would eb adaptive to remember the events that are emotionally important so that you could identify similar situations in the future and recall how to respond.

Christianson and Gubinette 1993 found evidence of enhanced recall when they questioned 58 real witnesses to bank robberies in Sweden. The witnesses were either victims (bank teller) or bystanders (employee or customer) - high and low anxiety respectively - the interviews were conducted 4-15 months after the robberies.

the researchers found that all witnesses showed generally good memories for details of the robbery itself (Better than 75% accurate recall). Those witnesses who were most anxious (the victims) had the best recall of it all. This study generally shows that anxiety does not reduce accuracy of recall.

Christianson 1992, in a review of research, concluded that memory for negative emotional events is better than for neutral events at least for the central details

Yerkes-dodson effect

• observation that arousal has a negative effect on performance such as memory recall - when it is low or very high, but moderate levels are actually beneficial.

• inverted U shape curve

• Kenneth Deffenbacher 2983 reviewed 21 studies of the effects of anxiety on eyewitness memory

• found 10 of these studies had results that linked higher arousal levels to increased eyewitness accuracy while 11 of them showed the opposite

• he suggested the Yerkes Dodson effect which can account for this inconsistency

• according to this principle there Ould eb occasions when anxiety/ arousal is only moderate and accuracy would be enhanced - too extreme then accuracy will be reduced

AO3 weapon focus effect may not be caused by anxiety

• the weapon focus effect may not be caused by anxiety

• a criticism of the weapon focus effect comes from Pickel 1998, who proposed that the reduced accuracy of identification could be due to surprise rather than anxiety

• to test this she arranged for particpants to watch a thief enter a hairdressing salon carrying scissors (high threat, low surprise), hand gun (high threat, high surprise), wallet (low threat, low surprise) or a whole raw chicken (low threat, high surprise) , identification was least accurate in the high surprise conditions rather than high threat

• this supports the view that the weapon focus effect is related to surprise rather than anxiety

AO3 - real life vs lab studies

one of the strengths of the study by Christianson and Hubinette was that it was a study of anxiety in the context of a real crime

it may well be the case that lab studies do not create real levels of anxiety experienced by a real eye witness during an actual crime. Deffenbacher et al 2004 agree with this but found, from a review of 34 studies, that lab studies in general demonstrate in general that anxiety leads to reduced accuracy and that real-life studies are associated with an even greater loss in accuracy

these findings are at odds with the result from the Christianson and hubinette, but suggest that the results from lab studies are valid as they are supported by most real lifestyle studies - lab studies+ real life crime suggest not the same anxiety but both leads to anxiety

AO3 no simple conclusion

• however there is no simple conclusion - critics of the weapon focus effect have suggested that the violence of a crime may affect the accuracy of recall.

• the study by christianson and hubinette concerned a violent real life crime

• many other studies of anxiety and accuracy of identification, even the real life ones, did not involve violence. like christianson and hubinette, Halford and Milne 2005 found that victims of violent crimes were most accurate in their recall of crime scene information that victims of non violent crimes

• this shows that there is no simple rule about the effect of anxiety on accuracy of eyewitness testimony